Support for Slack notifications

Slack notifications: remove debug log

Slack notifications: code lint

Slack notifications: code lint

Slack notifications: code lint

fix according to comments

README.md

@@ -17,7 +17,8 @@ Remark42 is a self-hosted, lightweight, and simple (yet functional) comment engi
 * Images upload with drag-and-drop
 * Extractor for recent comments, cross-post
 * RSS for all comments and each post
-* Telegram and email notifications
+* Telegram, Slack and email notifications for Admins (get notified for each new comment)
+* Email notifications for users (get notified when someone responds to your comment)
 * Export data to json with automatic backups
 * No external databases, everything embedded in a single data file
 * Fully dockerized and can be deployed in a single command
@@ -155,11 +156,13 @@ _this is the recommended way to run remark42_
 | auth.email.subj         | AUTH_EMAIL_SUBJ         | `remark42 confirmation`  | email subject                                   |
 | auth.email.content-type | AUTH_EMAIL_CONTENT_TYPE | `text/html`              | email content type                              |
 | auth.email.template     | AUTH_EMAIL_TEMPLATE     | none (predefined)        | custom email message template file              |
-| notify.type             | NOTIFY_TYPE             | none                     | type of notification (telegram and/or email)    |
+| notify.type             | NOTIFY_TYPE             | none                     | type of notification (telegram, slack and/or email) |
 | notify.queue            | NOTIFY_QUEUE            | `100`                    | size of notification queue                      |
 | notify.telegram.token   | NOTIFY_TELEGRAM_TOKEN   |                          | telegram token                                  |
 | notify.telegram.chan    | NOTIFY_TELEGRAM_CHAN    |                          | telegram channel                                |
 | notify.telegram.timeout | NOTIFY_TELEGRAM_TIMEOUT | `5s`                     | telegram timeout                                |
+| notify.slack.token      | NOTIFY_SLACK_TOKEN      |                          | slack token                                     |
+| notify.slack.chan       | NOTIFY_SLACK_CHAN       | `general`                | slack channel                                   |
 | notify.email.fromAddress | NOTIFY_EMAIL_FROM      |                          | from email address                              |
 | notify.email.verification_subj | NOTIFY_EMAIL_VERIFICATION_SUBJ | `Email verification` | verification message subject          |
 | notify.email.notify_admin | NOTIFY_EMAIL_ADMIN    | `false`                  | notify admin on new comments via ADMIN_SHARED_EMAIL |

backend/app/cmd/server.go

@@ -198,7 +198,7 @@ type SMTPGroup struct {
 
 // NotifyGroup defines options for notification
 type NotifyGroup struct {
-	Type      []string `long:"type" env:"TYPE" description:"type of notification" choice:"none" choice:"telegram" choice:"email" default:"none" env-delim:","` //nolint
+	Type      []string `long:"type" env:"TYPE" description:"type of notification" choice:"none" choice:"telegram" choice:"email" choice:"slack" default:"none" env-delim:","` //nolint
 	QueueSize int      `long:"queue" env:"QUEUE" description:"size of notification queue" default:"100"`
 	Telegram  struct {
 		Token   string        `long:"token" env:"TOKEN" description:"telegram token"`
@@ -211,6 +211,10 @@ type NotifyGroup struct {
 		VerificationSubject string `long:"verification_subj" env:"VERIFICATION_SUBJ" description:"verification message subject"`
 		AdminNotifications  bool   `long:"notify_admin" env:"ADMIN" description:"notify admin on new comments via ADMIN_SHARED_EMAIL"`
 	} `group:"email" namespace:"email" env-namespace:"EMAIL"`
+	Slack  struct {
+		Token   string        `long:"token" env:"TOKEN" description:"slack token"`
+		Channel string        `long:"chan" env:"CHAN" description:"slack channel"`
+	} `group:"slack" namespace:"slack" env-namespace:"SLACK"`
 }
 
 // SSLGroup defines options group for server ssl params
@@ -807,6 +811,12 @@ func (s *ServerCommand) makeNotify(dataStore *service.DataStore, authenticator *
 	var destinations []notify.Destination
 	for _, t := range s.Notify.Type {
 		switch t {
+		case "slack":
+			slack, err := notify.NewSlack(s.Notify.Slack.Token, s.Notify.Slack.Channel)
+			if err != nil {
+				return nil, errors.Wrap(err, "failed to create slack notification destination")
+			}
+			destinations = append(destinations, slack)
 		case "telegram":
 			tg, err := notify.NewTelegram(s.Notify.Telegram.Token, s.Notify.Telegram.Channel,
 				s.Notify.Telegram.Timeout, s.Notify.Telegram.API)

backend/app/notify/slack.go

@@ -0,0 +1,102 @@
+package notify
+
+import (
+	"context"
+	"fmt"
+
+	log "github.com/go-pkgz/lgr"
+	"github.com/pkg/errors"
+	"github.com/slack-go/slack"
+)
+
+// Slack implements notify.Destination for Slack
+type Slack struct {
+	channelID   string
+	channelName string
+	client      *slack.Client
+}
+
+// NewSlack makes Slack bot for notifications
+func NewSlack(token, channelName string, opts ...slack.Option) (*Slack, error) {
+
+	if channelName == "" {
+		channelName = "general"
+	}
+
+	client := slack.New(token, opts...)
+	res := &Slack{client: client, channelName: channelName}
+
+	channelID, err := res.findChannelIDByName(channelName)
+	if err != nil {
+		return nil, errors.Wrap(err, "can not find slack channel '"+channelName+"'")
+	}
+
+	res.channelID = channelID
+	log.Printf("[DEBUG] create new slack notifier for chan %s", channelID)
+
+	return res, nil
+}
+
+// Send to Slack channel
+func (t *Slack) Send(ctx context.Context, req Request) error {
+
+	log.Printf("[DEBUG] send slack notification, comment id %s", req.Comment.ID)
+
+	user := req.Comment.User.Name
+	if req.Comment.ParentID != "" {
+		user += " → " + req.parent.User.Name
+	}
+
+	title := fmt.Sprintf("↦ original comment")
+	if req.Comment.PostTitle != "" {
+		title = "↦ " + req.Comment.PostTitle
+	}
+
+	_, _, err := t.client.PostMessageContext(ctx, t.channelID,
+		slack.MsgOptionText("New comment from "+user, false),
+		slack.MsgOptionAttachments(
+			slack.Attachment{
+				TitleLink: req.Comment.Locator.URL + uiNav + req.Comment.ID,
+				Title:     title,
+				Text:      req.Comment.Orig,
+			},
+		),
+	)
+
+	return err
+
+}
+
+// SendVerification is not implemented for Slack
+func (t *Slack) SendVerification(_ context.Context, _ VerificationRequest) error {
+	return nil
+}
+
+func (t *Slack) String() string {
+	return "slack: " + t.channelName + " (" + t.channelID + ")"
+}
+
+func (t *Slack) findChannelIDByName(name string) (string, error) {
+
+	params := slack.GetConversationsParameters{}
+	for {
+
+		chans, next, err := t.client.GetConversations(&params)
+		if err != nil {
+			return "", err
+		}
+
+		for _, channel := range chans {
+			if channel.Name == name {
+				return channel.ID, nil
+			}
+		}
+
+		if next == "" {
+			break
+		}
+		params.Cursor = next
+
+	}
+	return "", errors.New("no such channel")
+}

backend/app/notify/slack_test.go

@@ -0,0 +1,170 @@
+package notify
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/go-chi/chi"
+	"github.com/slack-go/slack"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/umputun/remark42/backend/app/store"
+)
+
+func TestSlack_New(t *testing.T) {
+
+	ts := newMockSlackServer()
+	defer ts.Close()
+
+	tb, err := ts.newClient("general")
+	assert.NoError(t, err)
+	assert.NotNil(t, tb)
+	assert.Equal(t, "C12345678", tb.channelID)
+
+	_, err = ts.newClient("unknown-channel")
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "no such channel")
+
+}
+
+func TestSlack_Send(t *testing.T) {
+
+	ts := newMockSlackServer()
+	defer ts.Close()
+
+	tb, err := ts.newClient("general")
+	assert.NoError(t, err)
+	assert.NotNil(t, tb)
+
+	c := store.Comment{Text: "some text", ParentID: "1", ID: "999"}
+	c.User.Name = "from"
+	cp := store.Comment{Text: "some parent text"}
+	cp.User.Name = "to"
+
+	err = tb.Send(context.TODO(), Request{Comment: c, parent: cp})
+	assert.NoError(t, err)
+	c.PostTitle = "test title"
+	err = tb.Send(context.TODO(), Request{Comment: c, parent: cp})
+	assert.NoError(t, err)
+
+	err = tb.Send(context.TODO(), Request{Comment: c, parent: cp})
+	assert.NoError(t, err)
+	c.PostTitle = "[test title]"
+	err = tb.Send(context.TODO(), Request{Comment: c, parent: cp})
+	assert.NoError(t, err)
+
+	tb, err = ts.newClient("general")
+	assert.NoError(t, err)
+	ts.isServerDown = true
+	err = tb.Send(context.TODO(), Request{Comment: c, parent: cp})
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "slack server error", "send on broken client")
+
+}
+
+func TestSlack_Name(t *testing.T) {
+	ts := newMockSlackServer()
+	defer ts.Close()
+
+	tb, err := ts.newClient("general")
+	assert.NoError(t, err)
+	assert.NotNil(t, tb)
+	assert.Equal(t, "slack: general (C12345678)", tb.String())
+}
+
+func TestSlack_SendVerification(t *testing.T) {
+	ts := newMockSlackServer()
+	defer ts.Close()
+
+	tb, err := ts.newClient("general")
+	assert.NoError(t, err)
+	assert.NotNil(t, tb)
+
+	err = tb.SendVerification(context.TODO(), VerificationRequest{})
+	assert.NoError(t, err)
+}
+
+type mockSlackServer struct {
+	*httptest.Server
+	isServerDown bool
+}
+
+func (ts *mockSlackServer) newClient(channelName string) (*Slack, error) {
+	return NewSlack("any-token", channelName, slack.OptionAPIURL(ts.URL+"/"))
+}
+
+func newMockSlackServer() *mockSlackServer {
+
+	mockServer := mockSlackServer{}
+	router := chi.NewRouter()
+	router.Post("/conversations.list", func(w http.ResponseWriter, r *http.Request) {
+		s := `{
+		    "ok": true,
+		    "channels": [
+		        {
+		            "id": "C12345678",
+		            "name": "general",
+		            "is_channel": true,
+		            "is_group": false,
+		            "is_im": false,
+		            "created": 1503888888,
+		            "is_archived": false,
+		            "is_general": false,
+		            "unlinked": 0,
+		            "name_normalized": "random",
+		            "is_shared": false,
+		            "parent_conversation": null,
+		            "creator": "U12345678",
+		            "is_ext_shared": false,
+		            "is_org_shared": false,
+		            "pending_shared": [],
+		            "pending_connected_team_ids": [],
+		            "is_pending_ext_shared": false,
+		            "is_member": false,
+		            "is_private": false,
+		            "is_mpim": false,
+		            "previous_names": [],
+		            "num_members": 1
+		        }
+		    ],
+		    "response_metadata": {
+		        "next_cursor": ""
+		    }
+		}`
+		_, _ = w.Write([]byte(s))
+	})
+
+	router.Post("/chat.postMessage", func(w http.ResponseWriter, r *http.Request) {
+
+		if mockServer.isServerDown {
+			w.WriteHeader(500)
+
+		} else {
+			s := `{
+			    "ok": true,
+			    "channel": "C12345678",
+			    "ts": "1617008342.000100",
+			    "message": {
+			        "type": "message",
+			        "subtype": "bot_message",
+			        "text": "wowo",
+			        "ts": "1617008342.000100",
+			        "username": "slackbot",
+			        "bot_id": "B12345678"
+			    }
+			}`
+			_, _ = w.Write([]byte(s))
+		}
+	})
+
+	router.NotFound(func(w http.ResponseWriter, r *http.Request) {
+		log.Printf("..... 404 for %s .....\n", r.URL)
+	})
+
+	mockServer.Server = httptest.NewServer(router)
+	return &mockServer
+}

backend/go.mod

@@ -28,6 +28,7 @@ require (
 	github.com/rakyll/statik v0.1.7
 	github.com/rs/xid v1.2.1
 	github.com/russross/blackfriday/v2 v2.1.0
+	github.com/slack-go/slack v0.8.2
 	github.com/stretchr/testify v1.6.1
 	github.com/umputun/go-flags v1.5.1
 	go.etcd.io/bbolt v1.3.5

backend/go.sum

@@ -88,6 +88,7 @@ github.com/go-session/session v3.1.2+incompatible/go.mod h1:8B3iivBQjrz/JtC68Np2
 github.com/go-sql-driver/mysql v1.5.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
 github.com/go-stack/stack v1.8.0 h1:5SgMzNM5HxrEjV0ww2lTmX6E2Izsfxas4+YHWRs3Lsk=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
+github.com/go-test/deep v1.0.4/go.mod h1:wGDj63lr65AM2AQyKZd/NYHGb0R+1RLqB8NKt3aSFNA=
 github.com/gobuffalo/attrs v0.0.0-20190224210810-a9411de4debd/go.mod h1:4duuawTqi2wkkpB4ePgWMaai6/Kc6WEz83bhFwpHzj0=
 github.com/gobuffalo/depgen v0.0.0-20190329151759-d478694a28d3/go.mod h1:3STtPUQYuzV0gBVOY3vy6CfMm/ljR4pABfrTeHNLHUY=
 github.com/gobuffalo/depgen v0.1.0/go.mod h1:+ifsuy7fhi15RWncXQQKjWS9JPkdah5sZvtHc2RXGlg=
@@ -133,6 +134,8 @@ github.com/gorilla/feeds v1.1.1 h1:HwKXxqzcRNg9to+BbvJog4+f3s/xzvtZXICcQGutYfY=
 github.com/gorilla/feeds v1.1.1/go.mod h1:Nk0jZrvPFZX1OBe5NPiddPw7CfwF6Q9eqzaBbaightA=
 github.com/gorilla/websocket v1.4.1 h1:q7AeDBpnBk8AogcD4DSag/Ukw/KV+YhzLj2bP5HvKCM=
 github.com/gorilla/websocket v1.4.1/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
+github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
 github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
 github.com/hashicorp/go-multierror v1.1.0 h1:B9UzwGQJehnUY1yNrnwREHc3fGbC2xefo8g4TbElacI=
@@ -216,6 +219,8 @@ github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeV
 github.com/sirupsen/logrus v1.4.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
 github.com/sirupsen/logrus v1.4.1/go.mod h1:ni0Sbl8bgC9z8RoU9G6nDWqqs/fq4eDPysMBDgk/93Q=
 github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
+github.com/slack-go/slack v0.8.2 h1:D7jNu0AInBfdQ4QyKPtVSp+ZxQes3EzWW17RZ/va4JE=
+github.com/slack-go/slack v0.8.2/go.mod h1:FGqNzJBmxIsZURAxh2a8D21AnOVvvXZvGligs4npPUM=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d h1:zE9ykElWQ6/NYmHa3jpm/yHnI4xSofP+UP6SpjHcSeM=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
 github.com/smartystreets/goconvey v1.6.4 h1:fv0U8FUIMPNf1L9lnHLvLhgicrIVChEkdzIKYqbNC9s=

backend/vendor/github.com/gorilla/websocket/.gitignore

@@ -0,0 +1,25 @@
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+
+.idea/
+*.iml

backend/vendor/github.com/gorilla/websocket/AUTHORS

@@ -0,0 +1,9 @@
+# This is the official list of Gorilla WebSocket authors for copyright
+# purposes.
+#
+# Please keep the list sorted.
+
+Gary Burd <gary@beagledreams.com>
+Google LLC (https://opensource.google.com/)
+Joachim Bauch <mail@joachim-bauch.de>
+

backend/vendor/github.com/gorilla/websocket/LICENSE

@@ -0,0 +1,22 @@
+Copyright (c) 2013 The Gorilla WebSocket Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+  Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

backend/vendor/github.com/gorilla/websocket/README.md

@@ -0,0 +1,64 @@
+# Gorilla WebSocket
+
+[![GoDoc](https://godoc.org/github.com/gorilla/websocket?status.svg)](https://godoc.org/github.com/gorilla/websocket)
+[![CircleCI](https://circleci.com/gh/gorilla/websocket.svg?style=svg)](https://circleci.com/gh/gorilla/websocket)
+
+Gorilla WebSocket is a [Go](http://golang.org/) implementation of the
+[WebSocket](http://www.rfc-editor.org/rfc/rfc6455.txt) protocol.
+
+### Documentation
+
+* [API Reference](https://pkg.go.dev/github.com/gorilla/websocket?tab=doc)
+* [Chat example](https://github.com/gorilla/websocket/tree/master/examples/chat)
+* [Command example](https://github.com/gorilla/websocket/tree/master/examples/command)
+* [Client and server example](https://github.com/gorilla/websocket/tree/master/examples/echo)
+* [File watch example](https://github.com/gorilla/websocket/tree/master/examples/filewatch)
+
+### Status
+
+The Gorilla WebSocket package provides a complete and tested implementation of
+the [WebSocket](http://www.rfc-editor.org/rfc/rfc6455.txt) protocol. The
+package API is stable.
+
+### Installation
+
+    go get github.com/gorilla/websocket
+
+### Protocol Compliance
+
+The Gorilla WebSocket package passes the server tests in the [Autobahn Test
+Suite](https://github.com/crossbario/autobahn-testsuite) using the application in the [examples/autobahn
+subdirectory](https://github.com/gorilla/websocket/tree/master/examples/autobahn).
+
+### Gorilla WebSocket compared with other packages
+
+<table>
+<tr>
+<th></th>
+<th><a href="http://godoc.org/github.com/gorilla/websocket">github.com/gorilla</a></th>
+<th><a href="http://godoc.org/golang.org/x/net/websocket">golang.org/x/net</a></th>
+</tr>
+<tr>
+<tr><td colspan="3"><a href="http://tools.ietf.org/html/rfc6455">RFC 6455</a> Features</td></tr>
+<tr><td>Passes <a href="https://github.com/crossbario/autobahn-testsuite">Autobahn Test Suite</a></td><td><a href="https://github.com/gorilla/websocket/tree/master/examples/autobahn">Yes</a></td><td>No</td></tr>
+<tr><td>Receive <a href="https://tools.ietf.org/html/rfc6455#section-5.4">fragmented</a> message<td>Yes</td><td><a href="https://code.google.com/p/go/issues/detail?id=7632">No</a>, see note 1</td></tr>
+<tr><td>Send <a href="https://tools.ietf.org/html/rfc6455#section-5.5.1">close</a> message</td><td><a href="http://godoc.org/github.com/gorilla/websocket#hdr-Control_Messages">Yes</a></td><td><a href="https://code.google.com/p/go/issues/detail?id=4588">No</a></td></tr>
+<tr><td>Send <a href="https://tools.ietf.org/html/rfc6455#section-5.5.2">pings</a> and receive <a href="https://tools.ietf.org/html/rfc6455#section-5.5.3">pongs</a></td><td><a href="http://godoc.org/github.com/gorilla/websocket#hdr-Control_Messages">Yes</a></td><td>No</td></tr>
+<tr><td>Get the <a href="https://tools.ietf.org/html/rfc6455#section-5.6">type</a> of a received data message</td><td>Yes</td><td>Yes, see note 2</td></tr>
+<tr><td colspan="3">Other Features</tr></td>
+<tr><td><a href="https://tools.ietf.org/html/rfc7692">Compression Extensions</a></td><td>Experimental</td><td>No</td></tr>
+<tr><td>Read message using io.Reader</td><td><a href="http://godoc.org/github.com/gorilla/websocket#Conn.NextReader">Yes</a></td><td>No, see note 3</td></tr>
+<tr><td>Write message using io.WriteCloser</td><td><a href="http://godoc.org/github.com/gorilla/websocket#Conn.NextWriter">Yes</a></td><td>No, see note 3</td></tr>
+</table>
+
+Notes:
+
+1. Large messages are fragmented in [Chrome's new WebSocket implementation](http://www.ietf.org/mail-archive/web/hybi/current/msg10503.html).
+2. The application can get the type of a received data message by implementing
+   a [Codec marshal](http://godoc.org/golang.org/x/net/websocket#Codec.Marshal)
+   function.
+3. The go.net io.Reader and io.Writer operate across WebSocket frame boundaries.
+  Read returns when the input buffer is full or a frame boundary is
+  encountered. Each call to Write sends a single frame message. The Gorilla
+  io.Reader and io.WriteCloser operate on a single WebSocket message.
+

backend/vendor/github.com/gorilla/websocket/client.go

@@ -0,0 +1,395 @@
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"errors"
+	"io"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"net/http/httptrace"
+	"net/url"
+	"strings"
+	"time"
+)
+
+// ErrBadHandshake is returned when the server response to opening handshake is
+// invalid.
+var ErrBadHandshake = errors.New("websocket: bad handshake")
+
+var errInvalidCompression = errors.New("websocket: invalid compression negotiation")
+
+// NewClient creates a new client connection using the given net connection.
+// The URL u specifies the host and request URI. Use requestHeader to specify
+// the origin (Origin), subprotocols (Sec-WebSocket-Protocol) and cookies
+// (Cookie). Use the response.Header to get the selected subprotocol
+// (Sec-WebSocket-Protocol) and cookies (Set-Cookie).
+//
+// If the WebSocket handshake fails, ErrBadHandshake is returned along with a
+// non-nil *http.Response so that callers can handle redirects, authentication,
+// etc.
+//
+// Deprecated: Use Dialer instead.
+func NewClient(netConn net.Conn, u *url.URL, requestHeader http.Header, readBufSize, writeBufSize int) (c *Conn, response *http.Response, err error) {
+	d := Dialer{
+		ReadBufferSize:  readBufSize,
+		WriteBufferSize: writeBufSize,
+		NetDial: func(net, addr string) (net.Conn, error) {
+			return netConn, nil
+		},
+	}
+	return d.Dial(u.String(), requestHeader)
+}
+
+// A Dialer contains options for connecting to WebSocket server.
+type Dialer struct {
+	// NetDial specifies the dial function for creating TCP connections. If
+	// NetDial is nil, net.Dial is used.
+	NetDial func(network, addr string) (net.Conn, error)
+
+	// NetDialContext specifies the dial function for creating TCP connections. If
+	// NetDialContext is nil, net.DialContext is used.
+	NetDialContext func(ctx context.Context, network, addr string) (net.Conn, error)
+
+	// Proxy specifies a function to return a proxy for a given
+	// Request. If the function returns a non-nil error, the
+	// request is aborted with the provided error.
+	// If Proxy is nil or returns a nil *URL, no proxy is used.
+	Proxy func(*http.Request) (*url.URL, error)
+
+	// TLSClientConfig specifies the TLS configuration to use with tls.Client.
+	// If nil, the default configuration is used.
+	TLSClientConfig *tls.Config
+
+	// HandshakeTimeout specifies the duration for the handshake to complete.
+	HandshakeTimeout time.Duration
+
+	// ReadBufferSize and WriteBufferSize specify I/O buffer sizes in bytes. If a buffer
+	// size is zero, then a useful default size is used. The I/O buffer sizes
+	// do not limit the size of the messages that can be sent or received.
+	ReadBufferSize, WriteBufferSize int
+
+	// WriteBufferPool is a pool of buffers for write operations. If the value
+	// is not set, then write buffers are allocated to the connection for the
+	// lifetime of the connection.
+	//
+	// A pool is most useful when the application has a modest volume of writes
+	// across a large number of connections.
+	//
+	// Applications should use a single pool for each unique value of
+	// WriteBufferSize.
+	WriteBufferPool BufferPool
+
+	// Subprotocols specifies the client's requested subprotocols.
+	Subprotocols []string
+
+	// EnableCompression specifies if the client should attempt to negotiate
+	// per message compression (RFC 7692). Setting this value to true does not
+	// guarantee that compression will be supported. Currently only "no context
+	// takeover" modes are supported.
+	EnableCompression bool
+
+	// Jar specifies the cookie jar.
+	// If Jar is nil, cookies are not sent in requests and ignored
+	// in responses.
+	Jar http.CookieJar
+}
+
+// Dial creates a new client connection by calling DialContext with a background context.
+func (d *Dialer) Dial(urlStr string, requestHeader http.Header) (*Conn, *http.Response, error) {
+	return d.DialContext(context.Background(), urlStr, requestHeader)
+}
+
+var errMalformedURL = errors.New("malformed ws or wss URL")
+
+func hostPortNoPort(u *url.URL) (hostPort, hostNoPort string) {
+	hostPort = u.Host
+	hostNoPort = u.Host
+	if i := strings.LastIndex(u.Host, ":"); i > strings.LastIndex(u.Host, "]") {
+		hostNoPort = hostNoPort[:i]
+	} else {
+		switch u.Scheme {
+		case "wss":
+			hostPort += ":443"
+		case "https":
+			hostPort += ":443"
+		default:
+			hostPort += ":80"
+		}
+	}
+	return hostPort, hostNoPort
+}
+
+// DefaultDialer is a dialer with all fields set to the default values.
+var DefaultDialer = &Dialer{
+	Proxy:            http.ProxyFromEnvironment,
+	HandshakeTimeout: 45 * time.Second,
+}
+
+// nilDialer is dialer to use when receiver is nil.
+var nilDialer = *DefaultDialer
+
+// DialContext creates a new client connection. Use requestHeader to specify the
+// origin (Origin), subprotocols (Sec-WebSocket-Protocol) and cookies (Cookie).
+// Use the response.Header to get the selected subprotocol
+// (Sec-WebSocket-Protocol) and cookies (Set-Cookie).
+//
+// The context will be used in the request and in the Dialer.
+//
+// If the WebSocket handshake fails, ErrBadHandshake is returned along with a
+// non-nil *http.Response so that callers can handle redirects, authentication,
+// etcetera. The response body may not contain the entire response and does not
+// need to be closed by the application.
+func (d *Dialer) DialContext(ctx context.Context, urlStr string, requestHeader http.Header) (*Conn, *http.Response, error) {
+	if d == nil {
+		d = &nilDialer
+	}
+
+	challengeKey, err := generateChallengeKey()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	u, err := url.Parse(urlStr)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	switch u.Scheme {
+	case "ws":
+		u.Scheme = "http"
+	case "wss":
+		u.Scheme = "https"
+	default:
+		return nil, nil, errMalformedURL
+	}
+
+	if u.User != nil {
+		// User name and password are not allowed in websocket URIs.
+		return nil, nil, errMalformedURL
+	}
+
+	req := &http.Request{
+		Method:     "GET",
+		URL:        u,
+		Proto:      "HTTP/1.1",
+		ProtoMajor: 1,
+		ProtoMinor: 1,
+		Header:     make(http.Header),
+		Host:       u.Host,
+	}
+	req = req.WithContext(ctx)
+
+	// Set the cookies present in the cookie jar of the dialer
+	if d.Jar != nil {
+		for _, cookie := range d.Jar.Cookies(u) {
+			req.AddCookie(cookie)
+		}
+	}
+
+	// Set the request headers using the capitalization for names and values in
+	// RFC examples. Although the capitalization shouldn't matter, there are
+	// servers that depend on it. The Header.Set method is not used because the
+	// method canonicalizes the header names.
+	req.Header["Upgrade"] = []string{"websocket"}
+	req.Header["Connection"] = []string{"Upgrade"}
+	req.Header["Sec-WebSocket-Key"] = []string{challengeKey}
+	req.Header["Sec-WebSocket-Version"] = []string{"13"}
+	if len(d.Subprotocols) > 0 {
+		req.Header["Sec-WebSocket-Protocol"] = []string{strings.Join(d.Subprotocols, ", ")}
+	}
+	for k, vs := range requestHeader {
+		switch {
+		case k == "Host":
+			if len(vs) > 0 {
+				req.Host = vs[0]
+			}
+		case k == "Upgrade" ||
+			k == "Connection" ||
+			k == "Sec-Websocket-Key" ||
+			k == "Sec-Websocket-Version" ||
+			k == "Sec-Websocket-Extensions" ||
+			(k == "Sec-Websocket-Protocol" && len(d.Subprotocols) > 0):
+			return nil, nil, errors.New("websocket: duplicate header not allowed: " + k)
+		case k == "Sec-Websocket-Protocol":
+			req.Header["Sec-WebSocket-Protocol"] = vs
+		default:
+			req.Header[k] = vs
+		}
+	}
+
+	if d.EnableCompression {
+		req.Header["Sec-WebSocket-Extensions"] = []string{"permessage-deflate; server_no_context_takeover; client_no_context_takeover"}
+	}
+
+	if d.HandshakeTimeout != 0 {
+		var cancel func()
+		ctx, cancel = context.WithTimeout(ctx, d.HandshakeTimeout)
+		defer cancel()
+	}
+
+	// Get network dial function.
+	var netDial func(network, add string) (net.Conn, error)
+
+	if d.NetDialContext != nil {
+		netDial = func(network, addr string) (net.Conn, error) {
+			return d.NetDialContext(ctx, network, addr)
+		}
+	} else if d.NetDial != nil {
+		netDial = d.NetDial
+	} else {
+		netDialer := &net.Dialer{}
+		netDial = func(network, addr string) (net.Conn, error) {
+			return netDialer.DialContext(ctx, network, addr)
+		}
+	}
+
+	// If needed, wrap the dial function to set the connection deadline.
+	if deadline, ok := ctx.Deadline(); ok {
+		forwardDial := netDial
+		netDial = func(network, addr string) (net.Conn, error) {
+			c, err := forwardDial(network, addr)
+			if err != nil {
+				return nil, err
+			}
+			err = c.SetDeadline(deadline)
+			if err != nil {
+				c.Close()
+				return nil, err
+			}
+			return c, nil
+		}
+	}
+
+	// If needed, wrap the dial function to connect through a proxy.
+	if d.Proxy != nil {
+		proxyURL, err := d.Proxy(req)
+		if err != nil {
+			return nil, nil, err
+		}
+		if proxyURL != nil {
+			dialer, err := proxy_FromURL(proxyURL, netDialerFunc(netDial))
+			if err != nil {
+				return nil, nil, err
+			}
+			netDial = dialer.Dial
+		}
+	}
+
+	hostPort, hostNoPort := hostPortNoPort(u)
+	trace := httptrace.ContextClientTrace(ctx)
+	if trace != nil && trace.GetConn != nil {
+		trace.GetConn(hostPort)
+	}
+
+	netConn, err := netDial("tcp", hostPort)
+	if trace != nil && trace.GotConn != nil {
+		trace.GotConn(httptrace.GotConnInfo{
+			Conn: netConn,
+		})
+	}
+	if err != nil {
+		return nil, nil, err
+	}
+
+	defer func() {
+		if netConn != nil {
+			netConn.Close()
+		}
+	}()
+
+	if u.Scheme == "https" {
+		cfg := cloneTLSConfig(d.TLSClientConfig)
+		if cfg.ServerName == "" {
+			cfg.ServerName = hostNoPort
+		}
+		tlsConn := tls.Client(netConn, cfg)
+		netConn = tlsConn
+
+		var err error
+		if trace != nil {
+			err = doHandshakeWithTrace(trace, tlsConn, cfg)
+		} else {
+			err = doHandshake(tlsConn, cfg)
+		}
+
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+
+	conn := newConn(netConn, false, d.ReadBufferSize, d.WriteBufferSize, d.WriteBufferPool, nil, nil)
+
+	if err := req.Write(netConn); err != nil {
+		return nil, nil, err
+	}
+
+	if trace != nil && trace.GotFirstResponseByte != nil {
+		if peek, err := conn.br.Peek(1); err == nil && len(peek) == 1 {
+			trace.GotFirstResponseByte()
+		}
+	}
+
+	resp, err := http.ReadResponse(conn.br, req)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if d.Jar != nil {
+		if rc := resp.Cookies(); len(rc) > 0 {
+			d.Jar.SetCookies(u, rc)
+		}
+	}
+
+	if resp.StatusCode != 101 ||
+		!strings.EqualFold(resp.Header.Get("Upgrade"), "websocket") ||
+		!strings.EqualFold(resp.Header.Get("Connection"), "upgrade") ||
+		resp.Header.Get("Sec-Websocket-Accept") != computeAcceptKey(challengeKey) {
+		// Before closing the network connection on return from this
+		// function, slurp up some of the response to aid application
+		// debugging.
+		buf := make([]byte, 1024)
+		n, _ := io.ReadFull(resp.Body, buf)
+		resp.Body = ioutil.NopCloser(bytes.NewReader(buf[:n]))
+		return nil, resp, ErrBadHandshake
+	}
+
+	for _, ext := range parseExtensions(resp.Header) {
+		if ext[""] != "permessage-deflate" {
+			continue
+		}
+		_, snct := ext["server_no_context_takeover"]
+		_, cnct := ext["client_no_context_takeover"]
+		if !snct || !cnct {
+			return nil, resp, errInvalidCompression
+		}
+		conn.newCompressionWriter = compressNoContextTakeover
+		conn.newDecompressionReader = decompressNoContextTakeover
+		break
+	}
+
+	resp.Body = ioutil.NopCloser(bytes.NewReader([]byte{}))
+	conn.subprotocol = resp.Header.Get("Sec-Websocket-Protocol")
+
+	netConn.SetDeadline(time.Time{})
+	netConn = nil // to avoid close in defer.
+	return conn, resp, nil
+}
+
+func doHandshake(tlsConn *tls.Conn, cfg *tls.Config) error {
+	if err := tlsConn.Handshake(); err != nil {
+		return err
+	}
+	if !cfg.InsecureSkipVerify {
+		if err := tlsConn.VerifyHostname(cfg.ServerName); err != nil {
+			return err
+		}
+	}
+	return nil
+}

backend/vendor/github.com/gorilla/websocket/client_clone.go

@@ -0,0 +1,16 @@
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.8
+
+package websocket
+
+import "crypto/tls"
+
+func cloneTLSConfig(cfg *tls.Config) *tls.Config {
+	if cfg == nil {
+		return &tls.Config{}
+	}
+	return cfg.Clone()
+}

backend/vendor/github.com/gorilla/websocket/client_clone_legacy.go

@@ -0,0 +1,38 @@
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !go1.8
+
+package websocket
+
+import "crypto/tls"
+
+// cloneTLSConfig clones all public fields except the fields
+// SessionTicketsDisabled and SessionTicketKey. This avoids copying the
+// sync.Mutex in the sync.Once and makes it safe to call cloneTLSConfig on a
+// config in active use.
+func cloneTLSConfig(cfg *tls.Config) *tls.Config {
+	if cfg == nil {
+		return &tls.Config{}
+	}
+	return &tls.Config{
+		Rand:                     cfg.Rand,
+		Time:                     cfg.Time,
+		Certificates:             cfg.Certificates,
+		NameToCertificate:        cfg.NameToCertificate,
+		GetCertificate:           cfg.GetCertificate,
+		RootCAs:                  cfg.RootCAs,
+		NextProtos:               cfg.NextProtos,
+		ServerName:               cfg.ServerName,
+		ClientAuth:               cfg.ClientAuth,
+		ClientCAs:                cfg.ClientCAs,
+		InsecureSkipVerify:       cfg.InsecureSkipVerify,
+		CipherSuites:             cfg.CipherSuites,
+		PreferServerCipherSuites: cfg.PreferServerCipherSuites,
+		ClientSessionCache:       cfg.ClientSessionCache,
+		MinVersion:               cfg.MinVersion,
+		MaxVersion:               cfg.MaxVersion,
+		CurvePreferences:         cfg.CurvePreferences,
+	}
+}

backend/vendor/github.com/gorilla/websocket/compression.go

@@ -0,0 +1,148 @@
+// Copyright 2017 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"compress/flate"
+	"errors"
+	"io"
+	"strings"
+	"sync"
+)
+
+const (
+	minCompressionLevel     = -2 // flate.HuffmanOnly not defined in Go < 1.6
+	maxCompressionLevel     = flate.BestCompression
+	defaultCompressionLevel = 1
+)
+
+var (
+	flateWriterPools [maxCompressionLevel - minCompressionLevel + 1]sync.Pool
+	flateReaderPool  = sync.Pool{New: func() interface{} {
+		return flate.NewReader(nil)
+	}}
+)
+
+func decompressNoContextTakeover(r io.Reader) io.ReadCloser {
+	const tail =
+	// Add four bytes as specified in RFC
+	"\x00\x00\xff\xff" +
+		// Add final block to squelch unexpected EOF error from flate reader.
+		"\x01\x00\x00\xff\xff"
+
+	fr, _ := flateReaderPool.Get().(io.ReadCloser)
+	fr.(flate.Resetter).Reset(io.MultiReader(r, strings.NewReader(tail)), nil)
+	return &flateReadWrapper{fr}
+}
+
+func isValidCompressionLevel(level int) bool {
+	return minCompressionLevel <= level && level <= maxCompressionLevel
+}
+
+func compressNoContextTakeover(w io.WriteCloser, level int) io.WriteCloser {
+	p := &flateWriterPools[level-minCompressionLevel]
+	tw := &truncWriter{w: w}
+	fw, _ := p.Get().(*flate.Writer)
+	if fw == nil {
+		fw, _ = flate.NewWriter(tw, level)
+	} else {
+		fw.Reset(tw)
+	}
+	return &flateWriteWrapper{fw: fw, tw: tw, p: p}
+}
+
+// truncWriter is an io.Writer that writes all but the last four bytes of the
+// stream to another io.Writer.
+type truncWriter struct {
+	w io.WriteCloser
+	n int
+	p [4]byte
+}
+
+func (w *truncWriter) Write(p []byte) (int, error) {
+	n := 0
+
+	// fill buffer first for simplicity.
+	if w.n < len(w.p) {
+		n = copy(w.p[w.n:], p)
+		p = p[n:]
+		w.n += n
+		if len(p) == 0 {
+			return n, nil
+		}
+	}
+
+	m := len(p)
+	if m > len(w.p) {
+		m = len(w.p)
+	}
+
+	if nn, err := w.w.Write(w.p[:m]); err != nil {
+		return n + nn, err
+	}
+
+	copy(w.p[:], w.p[m:])
+	copy(w.p[len(w.p)-m:], p[len(p)-m:])
+	nn, err := w.w.Write(p[:len(p)-m])
+	return n + nn, err
+}
+
+type flateWriteWrapper struct {
+	fw *flate.Writer
+	tw *truncWriter
+	p  *sync.Pool
+}
+
+func (w *flateWriteWrapper) Write(p []byte) (int, error) {
+	if w.fw == nil {
+		return 0, errWriteClosed
+	}
+	return w.fw.Write(p)
+}
+
+func (w *flateWriteWrapper) Close() error {
+	if w.fw == nil {
+		return errWriteClosed
+	}
+	err1 := w.fw.Flush()
+	w.p.Put(w.fw)
+	w.fw = nil
+	if w.tw.p != [4]byte{0, 0, 0xff, 0xff} {
+		return errors.New("websocket: internal error, unexpected bytes at end of flate stream")
+	}
+	err2 := w.tw.w.Close()
+	if err1 != nil {
+		return err1
+	}
+	return err2
+}
+
+type flateReadWrapper struct {
+	fr io.ReadCloser
+}
+
+func (r *flateReadWrapper) Read(p []byte) (int, error) {
+	if r.fr == nil {
+		return 0, io.ErrClosedPipe
+	}
+	n, err := r.fr.Read(p)
+	if err == io.EOF {
+		// Preemptively place the reader back in the pool. This helps with
+		// scenarios where the application does not call NextReader() soon after
+		// this final read.
+		r.Close()
+	}
+	return n, err
+}
+
+func (r *flateReadWrapper) Close() error {
+	if r.fr == nil {
+		return io.ErrClosedPipe
+	}
+	err := r.fr.Close()
+	flateReaderPool.Put(r.fr)
+	r.fr = nil
+	return err
+}

backend/vendor/github.com/gorilla/websocket/conn_write.go

@@ -0,0 +1,15 @@
+// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build go1.8
+
+package websocket
+
+import "net"
+
+func (c *Conn) writeBufs(bufs ...[]byte) error {
+	b := net.Buffers(bufs)
+	_, err := b.WriteTo(c.conn)
+	return err
+}

backend/vendor/github.com/gorilla/websocket/conn_write_legacy.go

@@ -0,0 +1,18 @@
+// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !go1.8
+
+package websocket
+
+func (c *Conn) writeBufs(bufs ...[]byte) error {
+	for _, buf := range bufs {
+		if len(buf) > 0 {
+			if _, err := c.conn.Write(buf); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}

backend/vendor/github.com/gorilla/websocket/doc.go

@@ -0,0 +1,227 @@
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package websocket implements the WebSocket protocol defined in RFC 6455.
+//
+// Overview
+//
+// The Conn type represents a WebSocket connection. A server application calls
+// the Upgrader.Upgrade method from an HTTP request handler to get a *Conn:
+//
+//  var upgrader = websocket.Upgrader{
+//      ReadBufferSize:  1024,
+//      WriteBufferSize: 1024,
+//  }
+//
+//  func handler(w http.ResponseWriter, r *http.Request) {
+//      conn, err := upgrader.Upgrade(w, r, nil)
+//      if err != nil {
+//          log.Println(err)
+//          return
+//      }
+//      ... Use conn to send and receive messages.
+//  }
+//
+// Call the connection's WriteMessage and ReadMessage methods to send and
+// receive messages as a slice of bytes. This snippet of code shows how to echo
+// messages using these methods:
+//
+//  for {
+//      messageType, p, err := conn.ReadMessage()
+//      if err != nil {
+//          log.Println(err)
+//          return
+//      }
+//      if err := conn.WriteMessage(messageType, p); err != nil {
+//          log.Println(err)
+//          return
+//      }
+//  }
+//
+// In above snippet of code, p is a []byte and messageType is an int with value
+// websocket.BinaryMessage or websocket.TextMessage.
+//
+// An application can also send and receive messages using the io.WriteCloser
+// and io.Reader interfaces. To send a message, call the connection NextWriter
+// method to get an io.WriteCloser, write the message to the writer and close
+// the writer when done. To receive a message, call the connection NextReader
+// method to get an io.Reader and read until io.EOF is returned. This snippet
+// shows how to echo messages using the NextWriter and NextReader methods:
+//
+//  for {
+//      messageType, r, err := conn.NextReader()
+//      if err != nil {
+//          return
+//      }
+//      w, err := conn.NextWriter(messageType)
+//      if err != nil {
+//          return err
+//      }
+//      if _, err := io.Copy(w, r); err != nil {
+//          return err
+//      }
+//      if err := w.Close(); err != nil {
+//          return err
+//      }
+//  }
+//
+// Data Messages
+//
+// The WebSocket protocol distinguishes between text and binary data messages.
+// Text messages are interpreted as UTF-8 encoded text. The interpretation of
+// binary messages is left to the application.
+//
+// This package uses the TextMessage and BinaryMessage integer constants to
+// identify the two data message types. The ReadMessage and NextReader methods
+// return the type of the received message. The messageType argument to the
+// WriteMessage and NextWriter methods specifies the type of a sent message.
+//
+// It is the application's responsibility to ensure that text messages are
+// valid UTF-8 encoded text.
+//
+// Control Messages
+//
+// The WebSocket protocol defines three types of control messages: close, ping
+// and pong. Call the connection WriteControl, WriteMessage or NextWriter
+// methods to send a control message to the peer.
+//
+// Connections handle received close messages by calling the handler function
+// set with the SetCloseHandler method and by returning a *CloseError from the
+// NextReader, ReadMessage or the message Read method. The default close
+// handler sends a close message to the peer.
+//
+// Connections handle received ping messages by calling the handler function
+// set with the SetPingHandler method. The default ping handler sends a pong
+// message to the peer.
+//
+// Connections handle received pong messages by calling the handler function
+// set with the SetPongHandler method. The default pong handler does nothing.
+// If an application sends ping messages, then the application should set a
+// pong handler to receive the corresponding pong.
+//
+// The control message handler functions are called from the NextReader,
+// ReadMessage and message reader Read methods. The default close and ping
+// handlers can block these methods for a short time when the handler writes to
+// the connection.
+//
+// The application must read the connection to process close, ping and pong
+// messages sent from the peer. If the application is not otherwise interested
+// in messages from the peer, then the application should start a goroutine to
+// read and discard messages from the peer. A simple example is:
+//
+//  func readLoop(c *websocket.Conn) {
+//      for {
+//          if _, _, err := c.NextReader(); err != nil {
+//              c.Close()
+//              break
+//          }
+//      }
+//  }
+//
+// Concurrency
+//
+// Connections support one concurrent reader and one concurrent writer.
+//
+// Applications are responsible for ensuring that no more than one goroutine
+// calls the write methods (NextWriter, SetWriteDeadline, WriteMessage,
+// WriteJSON, EnableWriteCompression, SetCompressionLevel) concurrently and
+// that no more than one goroutine calls the read methods (NextReader,
+// SetReadDeadline, ReadMessage, ReadJSON, SetPongHandler, SetPingHandler)
+// concurrently.
+//
+// The Close and WriteControl methods can be called concurrently with all other
+// methods.
+//
+// Origin Considerations
+//
+// Web browsers allow Javascript applications to open a WebSocket connection to
+// any host. It's up to the server to enforce an origin policy using the Origin
+// request header sent by the browser.
+//
+// The Upgrader calls the function specified in the CheckOrigin field to check
+// the origin. If the CheckOrigin function returns false, then the Upgrade
+// method fails the WebSocket handshake with HTTP status 403.
+//
+// If the CheckOrigin field is nil, then the Upgrader uses a safe default: fail
+// the handshake if the Origin request header is present and the Origin host is
+// not equal to the Host request header.
+//
+// The deprecated package-level Upgrade function does not perform origin
+// checking. The application is responsible for checking the Origin header
+// before calling the Upgrade function.
+//
+// Buffers
+//
+// Connections buffer network input and output to reduce the number
+// of system calls when reading or writing messages.
+//
+// Write buffers are also used for constructing WebSocket frames. See RFC 6455,
+// Section 5 for a discussion of message framing. A WebSocket frame header is
+// written to the network each time a write buffer is flushed to the network.
+// Decreasing the size of the write buffer can increase the amount of framing
+// overhead on the connection.
+//
+// The buffer sizes in bytes are specified by the ReadBufferSize and
+// WriteBufferSize fields in the Dialer and Upgrader. The Dialer uses a default
+// size of 4096 when a buffer size field is set to zero. The Upgrader reuses
+// buffers created by the HTTP server when a buffer size field is set to zero.
+// The HTTP server buffers have a size of 4096 at the time of this writing.
+//
+// The buffer sizes do not limit the size of a message that can be read or
+// written by a connection.
+//
+// Buffers are held for the lifetime of the connection by default. If the
+// Dialer or Upgrader WriteBufferPool field is set, then a connection holds the
+// write buffer only when writing a message.
+//
+// Applications should tune the buffer sizes to balance memory use and
+// performance. Increasing the buffer size uses more memory, but can reduce the
+// number of system calls to read or write the network. In the case of writing,
+// increasing the buffer size can reduce the number of frame headers written to
+// the network.
+//
+// Some guidelines for setting buffer parameters are:
+//
+// Limit the buffer sizes to the maximum expected message size. Buffers larger
+// than the largest message do not provide any benefit.
+//
+// Depending on the distribution of message sizes, setting the buffer size to
+// a value less than the maximum expected message size can greatly reduce memory
+// use with a small impact on performance. Here's an example: If 99% of the
+// messages are smaller than 256 bytes and the maximum message size is 512
+// bytes, then a buffer size of 256 bytes will result in 1.01 more system calls
+// than a buffer size of 512 bytes. The memory savings is 50%.
+//
+// A write buffer pool is useful when the application has a modest number
+// writes over a large number of connections. when buffers are pooled, a larger
+// buffer size has a reduced impact on total memory use and has the benefit of
+// reducing system calls and frame overhead.
+//
+// Compression EXPERIMENTAL
+//
+// Per message compression extensions (RFC 7692) are experimentally supported
+// by this package in a limited capacity. Setting the EnableCompression option
+// to true in Dialer or Upgrader will attempt to negotiate per message deflate
+// support.
+//
+//  var upgrader = websocket.Upgrader{
+//      EnableCompression: true,
+//  }
+//
+// If compression was successfully negotiated with the connection's peer, any
+// message received in compressed form will be automatically decompressed.
+// All Read methods will return uncompressed bytes.
+//
+// Per message compression of messages written to a connection can be enabled
+// or disabled by calling the corresponding Conn method:
+//
+//  conn.EnableWriteCompression(false)
+//
+// Currently this package does not support compression with "context takeover".
+// This means that messages must be compressed and decompressed in isolation,
+// without retaining sliding window or dictionary state across messages. For
+// more details refer to RFC 7692.
+//
+// Use of compression is experimental and may result in decreased performance.
+package websocket

backend/vendor/github.com/gorilla/websocket/go.mod

@@ -0,0 +1,3 @@
+module github.com/gorilla/websocket
+
+go 1.12

backend/vendor/github.com/gorilla/websocket/join.go

@@ -0,0 +1,42 @@
+// Copyright 2019 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"io"
+	"strings"
+)
+
+// JoinMessages concatenates received messages to create a single io.Reader.
+// The string term is appended to each message. The returned reader does not
+// support concurrent calls to the Read method.
+func JoinMessages(c *Conn, term string) io.Reader {
+	return &joinReader{c: c, term: term}
+}
+
+type joinReader struct {
+	c    *Conn
+	term string
+	r    io.Reader
+}
+
+func (r *joinReader) Read(p []byte) (int, error) {
+	if r.r == nil {
+		var err error
+		_, r.r, err = r.c.NextReader()
+		if err != nil {
+			return 0, err
+		}
+		if r.term != "" {
+			r.r = io.MultiReader(r.r, strings.NewReader(r.term))
+		}
+	}
+	n, err := r.r.Read(p)
+	if err == io.EOF {
+		err = nil
+		r.r = nil
+	}
+	return n, err
+}

backend/vendor/github.com/gorilla/websocket/json.go

@@ -0,0 +1,60 @@
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"encoding/json"
+	"io"
+)
+
+// WriteJSON writes the JSON encoding of v as a message.
+//
+// Deprecated: Use c.WriteJSON instead.
+func WriteJSON(c *Conn, v interface{}) error {
+	return c.WriteJSON(v)
+}
+
+// WriteJSON writes the JSON encoding of v as a message.
+//
+// See the documentation for encoding/json Marshal for details about the
+// conversion of Go values to JSON.
+func (c *Conn) WriteJSON(v interface{}) error {
+	w, err := c.NextWriter(TextMessage)
+	if err != nil {
+		return err
+	}
+	err1 := json.NewEncoder(w).Encode(v)
+	err2 := w.Close()
+	if err1 != nil {
+		return err1
+	}
+	return err2
+}
+
+// ReadJSON reads the next JSON-encoded message from the connection and stores
+// it in the value pointed to by v.
+//
+// Deprecated: Use c.ReadJSON instead.
+func ReadJSON(c *Conn, v interface{}) error {
+	return c.ReadJSON(v)
+}
+
+// ReadJSON reads the next JSON-encoded message from the connection and stores
+// it in the value pointed to by v.
+//
+// See the documentation for the encoding/json Unmarshal function for details
+// about the conversion of JSON to a Go value.
+func (c *Conn) ReadJSON(v interface{}) error {
+	_, r, err := c.NextReader()
+	if err != nil {
+		return err
+	}
+	err = json.NewDecoder(r).Decode(v)
+	if err == io.EOF {
+		// One value is expected in the message.
+		err = io.ErrUnexpectedEOF
+	}
+	return err
+}

backend/vendor/github.com/gorilla/websocket/mask.go

@@ -0,0 +1,54 @@
+// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved.  Use of
+// this source code is governed by a BSD-style license that can be found in the
+// LICENSE file.
+
+// +build !appengine
+
+package websocket
+
+import "unsafe"
+
+const wordSize = int(unsafe.Sizeof(uintptr(0)))
+
+func maskBytes(key [4]byte, pos int, b []byte) int {
+	// Mask one byte at a time for small buffers.
+	if len(b) < 2*wordSize {
+		for i := range b {
+			b[i] ^= key[pos&3]
+			pos++
+		}
+		return pos & 3
+	}
+
+	// Mask one byte at a time to word boundary.
+	if n := int(uintptr(unsafe.Pointer(&b[0]))) % wordSize; n != 0 {
+		n = wordSize - n
+		for i := range b[:n] {
+			b[i] ^= key[pos&3]
+			pos++
+		}
+		b = b[n:]
+	}
+
+	// Create aligned word size key.
+	var k [wordSize]byte
+	for i := range k {
+		k[i] = key[(pos+i)&3]
+	}
+	kw := *(*uintptr)(unsafe.Pointer(&k))
+
+	// Mask one word at a time.
+	n := (len(b) / wordSize) * wordSize
+	for i := 0; i < n; i += wordSize {
+		*(*uintptr)(unsafe.Pointer(uintptr(unsafe.Pointer(&b[0])) + uintptr(i))) ^= kw
+	}
+
+	// Mask one byte at a time for remaining bytes.
+	b = b[n:]
+	for i := range b {
+		b[i] ^= key[pos&3]
+		pos++
+	}
+
+	return pos & 3
+}

backend/vendor/github.com/gorilla/websocket/mask_safe.go

@@ -0,0 +1,15 @@
+// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved.  Use of
+// this source code is governed by a BSD-style license that can be found in the
+// LICENSE file.
+
+// +build appengine
+
+package websocket
+
+func maskBytes(key [4]byte, pos int, b []byte) int {
+	for i := range b {
+		b[i] ^= key[pos&3]
+		pos++
+	}
+	return pos & 3
+}

backend/vendor/github.com/gorilla/websocket/prepared.go

@@ -0,0 +1,102 @@
+// Copyright 2017 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"bytes"
+	"net"
+	"sync"
+	"time"
+)
+
+// PreparedMessage caches on the wire representations of a message payload.
+// Use PreparedMessage to efficiently send a message payload to multiple
+// connections. PreparedMessage is especially useful when compression is used
+// because the CPU and memory expensive compression operation can be executed
+// once for a given set of compression options.
+type PreparedMessage struct {
+	messageType int
+	data        []byte
+	mu          sync.Mutex
+	frames      map[prepareKey]*preparedFrame
+}
+
+// prepareKey defines a unique set of options to cache prepared frames in PreparedMessage.
+type prepareKey struct {
+	isServer         bool
+	compress         bool
+	compressionLevel int
+}
+
+// preparedFrame contains data in wire representation.
+type preparedFrame struct {
+	once sync.Once
+	data []byte
+}
+
+// NewPreparedMessage returns an initialized PreparedMessage. You can then send
+// it to connection using WritePreparedMessage method. Valid wire
+// representation will be calculated lazily only once for a set of current
+// connection options.
+func NewPreparedMessage(messageType int, data []byte) (*PreparedMessage, error) {
+	pm := &PreparedMessage{
+		messageType: messageType,
+		frames:      make(map[prepareKey]*preparedFrame),
+		data:        data,
+	}
+
+	// Prepare a plain server frame.
+	_, frameData, err := pm.frame(prepareKey{isServer: true, compress: false})
+	if err != nil {
+		return nil, err
+	}
+
+	// To protect against caller modifying the data argument, remember the data
+	// copied to the plain server frame.
+	pm.data = frameData[len(frameData)-len(data):]
+	return pm, nil
+}
+
+func (pm *PreparedMessage) frame(key prepareKey) (int, []byte, error) {
+	pm.mu.Lock()
+	frame, ok := pm.frames[key]
+	if !ok {
+		frame = &preparedFrame{}
+		pm.frames[key] = frame
+	}
+	pm.mu.Unlock()
+
+	var err error
+	frame.once.Do(func() {
+		// Prepare a frame using a 'fake' connection.
+		// TODO: Refactor code in conn.go to allow more direct construction of
+		// the frame.
+		mu := make(chan struct{}, 1)
+		mu <- struct{}{}
+		var nc prepareConn
+		c := &Conn{
+			conn:                   &nc,
+			mu:                     mu,
+			isServer:               key.isServer,
+			compressionLevel:       key.compressionLevel,
+			enableWriteCompression: true,
+			writeBuf:               make([]byte, defaultWriteBufferSize+maxFrameHeaderSize),
+		}
+		if key.compress {
+			c.newCompressionWriter = compressNoContextTakeover
+		}
+		err = c.WriteMessage(pm.messageType, pm.data)
+		frame.data = nc.buf.Bytes()
+	})
+	return pm.messageType, frame.data, err
+}
+
+type prepareConn struct {
+	buf bytes.Buffer
+	net.Conn
+}
+
+func (pc *prepareConn) Write(p []byte) (int, error)        { return pc.buf.Write(p) }
+func (pc *prepareConn) SetWriteDeadline(t time.Time) error { return nil }

backend/vendor/github.com/gorilla/websocket/proxy.go

@@ -0,0 +1,77 @@
+// Copyright 2017 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"bufio"
+	"encoding/base64"
+	"errors"
+	"net"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+type netDialerFunc func(network, addr string) (net.Conn, error)
+
+func (fn netDialerFunc) Dial(network, addr string) (net.Conn, error) {
+	return fn(network, addr)
+}
+
+func init() {
+	proxy_RegisterDialerType("http", func(proxyURL *url.URL, forwardDialer proxy_Dialer) (proxy_Dialer, error) {
+		return &httpProxyDialer{proxyURL: proxyURL, forwardDial: forwardDialer.Dial}, nil
+	})
+}
+
+type httpProxyDialer struct {
+	proxyURL    *url.URL
+	forwardDial func(network, addr string) (net.Conn, error)
+}
+
+func (hpd *httpProxyDialer) Dial(network string, addr string) (net.Conn, error) {
+	hostPort, _ := hostPortNoPort(hpd.proxyURL)
+	conn, err := hpd.forwardDial(network, hostPort)
+	if err != nil {
+		return nil, err
+	}
+
+	connectHeader := make(http.Header)
+	if user := hpd.proxyURL.User; user != nil {
+		proxyUser := user.Username()
+		if proxyPassword, passwordSet := user.Password(); passwordSet {
+			credential := base64.StdEncoding.EncodeToString([]byte(proxyUser + ":" + proxyPassword))
+			connectHeader.Set("Proxy-Authorization", "Basic "+credential)
+		}
+	}
+
+	connectReq := &http.Request{
+		Method: "CONNECT",
+		URL:    &url.URL{Opaque: addr},
+		Host:   addr,
+		Header: connectHeader,
+	}
+
+	if err := connectReq.Write(conn); err != nil {
+		conn.Close()
+		return nil, err
+	}
+
+	// Read response. It's OK to use and discard buffered reader here becaue
+	// the remote server does not speak until spoken to.
+	br := bufio.NewReader(conn)
+	resp, err := http.ReadResponse(br, connectReq)
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+
+	if resp.StatusCode != 200 {
+		conn.Close()
+		f := strings.SplitN(resp.Status, " ", 2)
+		return nil, errors.New(f[1])
+	}
+	return conn, nil
+}

backend/vendor/github.com/gorilla/websocket/server.go

@@ -0,0 +1,363 @@
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+)
+
+// HandshakeError describes an error with the handshake from the peer.
+type HandshakeError struct {
+	message string
+}
+
+func (e HandshakeError) Error() string { return e.message }
+
+// Upgrader specifies parameters for upgrading an HTTP connection to a
+// WebSocket connection.
+type Upgrader struct {
+	// HandshakeTimeout specifies the duration for the handshake to complete.
+	HandshakeTimeout time.Duration
+
+	// ReadBufferSize and WriteBufferSize specify I/O buffer sizes in bytes. If a buffer
+	// size is zero, then buffers allocated by the HTTP server are used. The
+	// I/O buffer sizes do not limit the size of the messages that can be sent
+	// or received.
+	ReadBufferSize, WriteBufferSize int
+
+	// WriteBufferPool is a pool of buffers for write operations. If the value
+	// is not set, then write buffers are allocated to the connection for the
+	// lifetime of the connection.
+	//
+	// A pool is most useful when the application has a modest volume of writes
+	// across a large number of connections.
+	//
+	// Applications should use a single pool for each unique value of
+	// WriteBufferSize.
+	WriteBufferPool BufferPool
+
+	// Subprotocols specifies the server's supported protocols in order of
+	// preference. If this field is not nil, then the Upgrade method negotiates a
+	// subprotocol by selecting the first match in this list with a protocol
+	// requested by the client. If there's no match, then no protocol is
+	// negotiated (the Sec-Websocket-Protocol header is not included in the
+	// handshake response).
+	Subprotocols []string
+
+	// Error specifies the function for generating HTTP error responses. If Error
+	// is nil, then http.Error is used to generate the HTTP response.
+	Error func(w http.ResponseWriter, r *http.Request, status int, reason error)
+
+	// CheckOrigin returns true if the request Origin header is acceptable. If
+	// CheckOrigin is nil, then a safe default is used: return false if the
+	// Origin request header is present and the origin host is not equal to
+	// request Host header.
+	//
+	// A CheckOrigin function should carefully validate the request origin to
+	// prevent cross-site request forgery.
+	CheckOrigin func(r *http.Request) bool
+
+	// EnableCompression specify if the server should attempt to negotiate per
+	// message compression (RFC 7692). Setting this value to true does not
+	// guarantee that compression will be supported. Currently only "no context
+	// takeover" modes are supported.
+	EnableCompression bool
+}
+
+func (u *Upgrader) returnError(w http.ResponseWriter, r *http.Request, status int, reason string) (*Conn, error) {
+	err := HandshakeError{reason}
+	if u.Error != nil {
+		u.Error(w, r, status, err)
+	} else {
+		w.Header().Set("Sec-Websocket-Version", "13")
+		http.Error(w, http.StatusText(status), status)
+	}
+	return nil, err
+}
+
+// checkSameOrigin returns true if the origin is not set or is equal to the request host.
+func checkSameOrigin(r *http.Request) bool {
+	origin := r.Header["Origin"]
+	if len(origin) == 0 {
+		return true
+	}
+	u, err := url.Parse(origin[0])
+	if err != nil {
+		return false
+	}
+	return equalASCIIFold(u.Host, r.Host)
+}
+
+func (u *Upgrader) selectSubprotocol(r *http.Request, responseHeader http.Header) string {
+	if u.Subprotocols != nil {
+		clientProtocols := Subprotocols(r)
+		for _, serverProtocol := range u.Subprotocols {
+			for _, clientProtocol := range clientProtocols {
+				if clientProtocol == serverProtocol {
+					return clientProtocol
+				}
+			}
+		}
+	} else if responseHeader != nil {
+		return responseHeader.Get("Sec-Websocket-Protocol")
+	}
+	return ""
+}
+
+// Upgrade upgrades the HTTP server connection to the WebSocket protocol.
+//
+// The responseHeader is included in the response to the client's upgrade
+// request. Use the responseHeader to specify cookies (Set-Cookie) and the
+// application negotiated subprotocol (Sec-WebSocket-Protocol).
+//
+// If the upgrade fails, then Upgrade replies to the client with an HTTP error
+// response.
+func (u *Upgrader) Upgrade(w http.ResponseWriter, r *http.Request, responseHeader http.Header) (*Conn, error) {
+	const badHandshake = "websocket: the client is not using the websocket protocol: "
+
+	if !tokenListContainsValue(r.Header, "Connection", "upgrade") {
+		return u.returnError(w, r, http.StatusBadRequest, badHandshake+"'upgrade' token not found in 'Connection' header")
+	}
+
+	if !tokenListContainsValue(r.Header, "Upgrade", "websocket") {
+		return u.returnError(w, r, http.StatusBadRequest, badHandshake+"'websocket' token not found in 'Upgrade' header")
+	}
+
+	if r.Method != "GET" {
+		return u.returnError(w, r, http.StatusMethodNotAllowed, badHandshake+"request method is not GET")
+	}
+
+	if !tokenListContainsValue(r.Header, "Sec-Websocket-Version", "13") {
+		return u.returnError(w, r, http.StatusBadRequest, "websocket: unsupported version: 13 not found in 'Sec-Websocket-Version' header")
+	}
+
+	if _, ok := responseHeader["Sec-Websocket-Extensions"]; ok {
+		return u.returnError(w, r, http.StatusInternalServerError, "websocket: application specific 'Sec-WebSocket-Extensions' headers are unsupported")
+	}
+
+	checkOrigin := u.CheckOrigin
+	if checkOrigin == nil {
+		checkOrigin = checkSameOrigin
+	}
+	if !checkOrigin(r) {
+		return u.returnError(w, r, http.StatusForbidden, "websocket: request origin not allowed by Upgrader.CheckOrigin")
+	}
+
+	challengeKey := r.Header.Get("Sec-Websocket-Key")
+	if challengeKey == "" {
+		return u.returnError(w, r, http.StatusBadRequest, "websocket: not a websocket handshake: 'Sec-WebSocket-Key' header is missing or blank")
+	}
+
+	subprotocol := u.selectSubprotocol(r, responseHeader)
+
+	// Negotiate PMCE
+	var compress bool
+	if u.EnableCompression {
+		for _, ext := range parseExtensions(r.Header) {
+			if ext[""] != "permessage-deflate" {
+				continue
+			}
+			compress = true
+			break
+		}
+	}
+
+	h, ok := w.(http.Hijacker)
+	if !ok {
+		return u.returnError(w, r, http.StatusInternalServerError, "websocket: response does not implement http.Hijacker")
+	}
+	var brw *bufio.ReadWriter
+	netConn, brw, err := h.Hijack()
+	if err != nil {
+		return u.returnError(w, r, http.StatusInternalServerError, err.Error())
+	}
+
+	if brw.Reader.Buffered() > 0 {
+		netConn.Close()
+		return nil, errors.New("websocket: client sent data before handshake is complete")
+	}
+
+	var br *bufio.Reader
+	if u.ReadBufferSize == 0 && bufioReaderSize(netConn, brw.Reader) > 256 {
+		// Reuse hijacked buffered reader as connection reader.
+		br = brw.Reader
+	}
+
+	buf := bufioWriterBuffer(netConn, brw.Writer)
+
+	var writeBuf []byte
+	if u.WriteBufferPool == nil && u.WriteBufferSize == 0 && len(buf) >= maxFrameHeaderSize+256 {
+		// Reuse hijacked write buffer as connection buffer.
+		writeBuf = buf
+	}
+
+	c := newConn(netConn, true, u.ReadBufferSize, u.WriteBufferSize, u.WriteBufferPool, br, writeBuf)
+	c.subprotocol = subprotocol
+
+	if compress {
+		c.newCompressionWriter = compressNoContextTakeover
+		c.newDecompressionReader = decompressNoContextTakeover
+	}
+
+	// Use larger of hijacked buffer and connection write buffer for header.
+	p := buf
+	if len(c.writeBuf) > len(p) {
+		p = c.writeBuf
+	}
+	p = p[:0]
+
+	p = append(p, "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: "...)
+	p = append(p, computeAcceptKey(challengeKey)...)
+	p = append(p, "\r\n"...)
+	if c.subprotocol != "" {
+		p = append(p, "Sec-WebSocket-Protocol: "...)
+		p = append(p, c.subprotocol...)
+		p = append(p, "\r\n"...)
+	}
+	if compress {
+		p = append(p, "Sec-WebSocket-Extensions: permessage-deflate; server_no_context_takeover; client_no_context_takeover\r\n"...)
+	}
+	for k, vs := range responseHeader {
+		if k == "Sec-Websocket-Protocol" {
+			continue
+		}
+		for _, v := range vs {
+			p = append(p, k...)
+			p = append(p, ": "...)
+			for i := 0; i < len(v); i++ {
+				b := v[i]
+				if b <= 31 {
+					// prevent response splitting.
+					b = ' '
+				}
+				p = append(p, b)
+			}
+			p = append(p, "\r\n"...)
+		}
+	}
+	p = append(p, "\r\n"...)
+
+	// Clear deadlines set by HTTP server.
+	netConn.SetDeadline(time.Time{})
+
+	if u.HandshakeTimeout > 0 {
+		netConn.SetWriteDeadline(time.Now().Add(u.HandshakeTimeout))
+	}
+	if _, err = netConn.Write(p); err != nil {
+		netConn.Close()
+		return nil, err
+	}
+	if u.HandshakeTimeout > 0 {
+		netConn.SetWriteDeadline(time.Time{})
+	}
+
+	return c, nil
+}
+
+// Upgrade upgrades the HTTP server connection to the WebSocket protocol.
+//
+// Deprecated: Use websocket.Upgrader instead.
+//
+// Upgrade does not perform origin checking. The application is responsible for
+// checking the Origin header before calling Upgrade. An example implementation
+// of the same origin policy check is:
+//
+//	if req.Header.Get("Origin") != "http://"+req.Host {
+//		http.Error(w, "Origin not allowed", http.StatusForbidden)
+//		return
+//	}
+//
+// If the endpoint supports subprotocols, then the application is responsible
+// for negotiating the protocol used on the connection. Use the Subprotocols()
+// function to get the subprotocols requested by the client. Use the
+// Sec-Websocket-Protocol response header to specify the subprotocol selected
+// by the application.
+//
+// The responseHeader is included in the response to the client's upgrade
+// request. Use the responseHeader to specify cookies (Set-Cookie) and the
+// negotiated subprotocol (Sec-Websocket-Protocol).
+//
+// The connection buffers IO to the underlying network connection. The
+// readBufSize and writeBufSize parameters specify the size of the buffers to
+// use. Messages can be larger than the buffers.
+//
+// If the request is not a valid WebSocket handshake, then Upgrade returns an
+// error of type HandshakeError. Applications should handle this error by
+// replying to the client with an HTTP error response.
+func Upgrade(w http.ResponseWriter, r *http.Request, responseHeader http.Header, readBufSize, writeBufSize int) (*Conn, error) {
+	u := Upgrader{ReadBufferSize: readBufSize, WriteBufferSize: writeBufSize}
+	u.Error = func(w http.ResponseWriter, r *http.Request, status int, reason error) {
+		// don't return errors to maintain backwards compatibility
+	}
+	u.CheckOrigin = func(r *http.Request) bool {
+		// allow all connections by default
+		return true
+	}
+	return u.Upgrade(w, r, responseHeader)
+}
+
+// Subprotocols returns the subprotocols requested by the client in the
+// Sec-Websocket-Protocol header.
+func Subprotocols(r *http.Request) []string {
+	h := strings.TrimSpace(r.Header.Get("Sec-Websocket-Protocol"))
+	if h == "" {
+		return nil
+	}
+	protocols := strings.Split(h, ",")
+	for i := range protocols {
+		protocols[i] = strings.TrimSpace(protocols[i])
+	}
+	return protocols
+}
+
+// IsWebSocketUpgrade returns true if the client requested upgrade to the
+// WebSocket protocol.
+func IsWebSocketUpgrade(r *http.Request) bool {
+	return tokenListContainsValue(r.Header, "Connection", "upgrade") &&
+		tokenListContainsValue(r.Header, "Upgrade", "websocket")
+}
+
+// bufioReaderSize size returns the size of a bufio.Reader.
+func bufioReaderSize(originalReader io.Reader, br *bufio.Reader) int {
+	// This code assumes that peek on a reset reader returns
+	// bufio.Reader.buf[:0].
+	// TODO: Use bufio.Reader.Size() after Go 1.10
+	br.Reset(originalReader)
+	if p, err := br.Peek(0); err == nil {
+		return cap(p)
+	}
+	return 0
+}
+
+// writeHook is an io.Writer that records the last slice passed to it vio
+// io.Writer.Write.
+type writeHook struct {
+	p []byte
+}
+
+func (wh *writeHook) Write(p []byte) (int, error) {
+	wh.p = p
+	return len(p), nil
+}
+
+// bufioWriterBuffer grabs the buffer from a bufio.Writer.
+func bufioWriterBuffer(originalWriter io.Writer, bw *bufio.Writer) []byte {
+	// This code assumes that bufio.Writer.buf[:1] is passed to the
+	// bufio.Writer's underlying writer.
+	var wh writeHook
+	bw.Reset(&wh)
+	bw.WriteByte(0)
+	bw.Flush()
+
+	bw.Reset(originalWriter)
+
+	return wh.p[:cap(wh.p)]
+}

backend/vendor/github.com/gorilla/websocket/trace.go

@@ -0,0 +1,19 @@
+// +build go1.8
+
+package websocket
+
+import (
+	"crypto/tls"
+	"net/http/httptrace"
+)
+
+func doHandshakeWithTrace(trace *httptrace.ClientTrace, tlsConn *tls.Conn, cfg *tls.Config) error {
+	if trace.TLSHandshakeStart != nil {
+		trace.TLSHandshakeStart()
+	}
+	err := doHandshake(tlsConn, cfg)
+	if trace.TLSHandshakeDone != nil {
+		trace.TLSHandshakeDone(tlsConn.ConnectionState(), err)
+	}
+	return err
+}

backend/vendor/github.com/gorilla/websocket/trace_17.go

@@ -0,0 +1,12 @@
+// +build !go1.8
+
+package websocket
+
+import (
+	"crypto/tls"
+	"net/http/httptrace"
+)
+
+func doHandshakeWithTrace(trace *httptrace.ClientTrace, tlsConn *tls.Conn, cfg *tls.Config) error {
+	return doHandshake(tlsConn, cfg)
+}

backend/vendor/github.com/gorilla/websocket/util.go

@@ -0,0 +1,283 @@
+// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package websocket
+
+import (
+	"crypto/rand"
+	"crypto/sha1"
+	"encoding/base64"
+	"io"
+	"net/http"
+	"strings"
+	"unicode/utf8"
+)
+
+var keyGUID = []byte("258EAFA5-E914-47DA-95CA-C5AB0DC85B11")
+
+func computeAcceptKey(challengeKey string) string {
+	h := sha1.New()
+	h.Write([]byte(challengeKey))
+	h.Write(keyGUID)
+	return base64.StdEncoding.EncodeToString(h.Sum(nil))
+}
+
+func generateChallengeKey() (string, error) {
+	p := make([]byte, 16)
+	if _, err := io.ReadFull(rand.Reader, p); err != nil {
+		return "", err
+	}
+	return base64.StdEncoding.EncodeToString(p), nil
+}
+
+// Token octets per RFC 2616.
+var isTokenOctet = [256]bool{
+	'!':  true,
+	'#':  true,
+	'$':  true,
+	'%':  true,
+	'&':  true,
+	'\'': true,
+	'*':  true,
+	'+':  true,
+	'-':  true,
+	'.':  true,
+	'0':  true,
+	'1':  true,
+	'2':  true,
+	'3':  true,
+	'4':  true,
+	'5':  true,
+	'6':  true,
+	'7':  true,
+	'8':  true,
+	'9':  true,
+	'A':  true,
+	'B':  true,
+	'C':  true,
+	'D':  true,
+	'E':  true,
+	'F':  true,
+	'G':  true,
+	'H':  true,
+	'I':  true,
+	'J':  true,
+	'K':  true,
+	'L':  true,
+	'M':  true,
+	'N':  true,
+	'O':  true,
+	'P':  true,
+	'Q':  true,
+	'R':  true,
+	'S':  true,
+	'T':  true,
+	'U':  true,
+	'W':  true,
+	'V':  true,
+	'X':  true,
+	'Y':  true,
+	'Z':  true,
+	'^':  true,
+	'_':  true,
+	'`':  true,
+	'a':  true,
+	'b':  true,
+	'c':  true,
+	'd':  true,
+	'e':  true,
+	'f':  true,
+	'g':  true,
+	'h':  true,
+	'i':  true,
+	'j':  true,
+	'k':  true,
+	'l':  true,
+	'm':  true,
+	'n':  true,
+	'o':  true,
+	'p':  true,
+	'q':  true,
+	'r':  true,
+	's':  true,
+	't':  true,
+	'u':  true,
+	'v':  true,
+	'w':  true,
+	'x':  true,
+	'y':  true,
+	'z':  true,
+	'|':  true,
+	'~':  true,
+}
+
+// skipSpace returns a slice of the string s with all leading RFC 2616 linear
+// whitespace removed.
+func skipSpace(s string) (rest string) {
+	i := 0
+	for ; i < len(s); i++ {
+		if b := s[i]; b != ' ' && b != '\t' {
+			break
+		}
+	}
+	return s[i:]
+}
+
+// nextToken returns the leading RFC 2616 token of s and the string following
+// the token.
+func nextToken(s string) (token, rest string) {
+	i := 0
+	for ; i < len(s); i++ {
+		if !isTokenOctet[s[i]] {
+			break
+		}
+	}
+	return s[:i], s[i:]
+}
+
+// nextTokenOrQuoted returns the leading token or quoted string per RFC 2616
+// and the string following the token or quoted string.
+func nextTokenOrQuoted(s string) (value string, rest string) {
+	if !strings.HasPrefix(s, "\"") {
+		return nextToken(s)
+	}
+	s = s[1:]
+	for i := 0; i < len(s); i++ {
+		switch s[i] {
+		case '"':
+			return s[:i], s[i+1:]
+		case '\\':
+			p := make([]byte, len(s)-1)
+			j := copy(p, s[:i])
+			escape := true
+			for i = i + 1; i < len(s); i++ {
+				b := s[i]
+				switch {
+				case escape:
+					escape = false
+					p[j] = b
+					j++
+				case b == '\\':
+					escape = true
+				case b == '"':
+					return string(p[:j]), s[i+1:]
+				default:
+					p[j] = b
+					j++
+				}
+			}
+			return "", ""
+		}
+	}
+	return "", ""
+}
+
+// equalASCIIFold returns true if s is equal to t with ASCII case folding as
+// defined in RFC 4790.
+func equalASCIIFold(s, t string) bool {
+	for s != "" && t != "" {
+		sr, size := utf8.DecodeRuneInString(s)
+		s = s[size:]
+		tr, size := utf8.DecodeRuneInString(t)
+		t = t[size:]
+		if sr == tr {
+			continue
+		}
+		if 'A' <= sr && sr <= 'Z' {
+			sr = sr + 'a' - 'A'
+		}
+		if 'A' <= tr && tr <= 'Z' {
+			tr = tr + 'a' - 'A'
+		}
+		if sr != tr {
+			return false
+		}
+	}
+	return s == t
+}
+
+// tokenListContainsValue returns true if the 1#token header with the given
+// name contains a token equal to value with ASCII case folding.
+func tokenListContainsValue(header http.Header, name string, value string) bool {
+headers:
+	for _, s := range header[name] {
+		for {
+			var t string
+			t, s = nextToken(skipSpace(s))
+			if t == "" {
+				continue headers
+			}
+			s = skipSpace(s)
+			if s != "" && s[0] != ',' {
+				continue headers
+			}
+			if equalASCIIFold(t, value) {
+				return true
+			}
+			if s == "" {
+				continue headers
+			}
+			s = s[1:]
+		}
+	}
+	return false
+}
+
+// parseExtensions parses WebSocket extensions from a header.
+func parseExtensions(header http.Header) []map[string]string {
+	// From RFC 6455:
+	//
+	//  Sec-WebSocket-Extensions = extension-list
+	//  extension-list = 1#extension
+	//  extension = extension-token *( ";" extension-param )
+	//  extension-token = registered-token
+	//  registered-token = token
+	//  extension-param = token [ "=" (token | quoted-string) ]
+	//     ;When using the quoted-string syntax variant, the value
+	//     ;after quoted-string unescaping MUST conform to the
+	//     ;'token' ABNF.
+
+	var result []map[string]string
+headers:
+	for _, s := range header["Sec-Websocket-Extensions"] {
+		for {
+			var t string
+			t, s = nextToken(skipSpace(s))
+			if t == "" {
+				continue headers
+			}
+			ext := map[string]string{"": t}
+			for {
+				s = skipSpace(s)
+				if !strings.HasPrefix(s, ";") {
+					break
+				}
+				var k string
+				k, s = nextToken(skipSpace(s[1:]))
+				if k == "" {
+					continue headers
+				}
+				s = skipSpace(s)
+				var v string
+				if strings.HasPrefix(s, "=") {
+					v, s = nextTokenOrQuoted(skipSpace(s[1:]))
+					s = skipSpace(s)
+				}
+				if s != "" && s[0] != ',' && s[0] != ';' {
+					continue headers
+				}
+				ext[k] = v
+			}
+			if s != "" && s[0] != ',' {
+				continue headers
+			}
+			result = append(result, ext)
+			if s == "" {
+				continue headers
+			}
+			s = s[1:]
+		}
+	}
+	return result
+}

backend/vendor/github.com/gorilla/websocket/x_net_proxy.go

@@ -0,0 +1,473 @@
+// Code generated by golang.org/x/tools/cmd/bundle. DO NOT EDIT.
+//go:generate bundle -o x_net_proxy.go golang.org/x/net/proxy
+
+// Package proxy provides support for a variety of protocols to proxy network
+// data.
+//
+
+package websocket
+
+import (
+	"errors"
+	"io"
+	"net"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+type proxy_direct struct{}
+
+// Direct is a direct proxy: one that makes network connections directly.
+var proxy_Direct = proxy_direct{}
+
+func (proxy_direct) Dial(network, addr string) (net.Conn, error) {
+	return net.Dial(network, addr)
+}
+
+// A PerHost directs connections to a default Dialer unless the host name
+// requested matches one of a number of exceptions.
+type proxy_PerHost struct {
+	def, bypass proxy_Dialer
+
+	bypassNetworks []*net.IPNet
+	bypassIPs      []net.IP
+	bypassZones    []string
+	bypassHosts    []string
+}
+
+// NewPerHost returns a PerHost Dialer that directs connections to either
+// defaultDialer or bypass, depending on whether the connection matches one of
+// the configured rules.
+func proxy_NewPerHost(defaultDialer, bypass proxy_Dialer) *proxy_PerHost {
+	return &proxy_PerHost{
+		def:    defaultDialer,
+		bypass: bypass,
+	}
+}
+
+// Dial connects to the address addr on the given network through either
+// defaultDialer or bypass.
+func (p *proxy_PerHost) Dial(network, addr string) (c net.Conn, err error) {
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, err
+	}
+
+	return p.dialerForRequest(host).Dial(network, addr)
+}
+
+func (p *proxy_PerHost) dialerForRequest(host string) proxy_Dialer {
+	if ip := net.ParseIP(host); ip != nil {
+		for _, net := range p.bypassNetworks {
+			if net.Contains(ip) {
+				return p.bypass
+			}
+		}
+		for _, bypassIP := range p.bypassIPs {
+			if bypassIP.Equal(ip) {
+				return p.bypass
+			}
+		}
+		return p.def
+	}
+
+	for _, zone := range p.bypassZones {
+		if strings.HasSuffix(host, zone) {
+			return p.bypass
+		}
+		if host == zone[1:] {
+			// For a zone ".example.com", we match "example.com"
+			// too.
+			return p.bypass
+		}
+	}
+	for _, bypassHost := range p.bypassHosts {
+		if bypassHost == host {
+			return p.bypass
+		}
+	}
+	return p.def
+}
+
+// AddFromString parses a string that contains comma-separated values
+// specifying hosts that should use the bypass proxy. Each value is either an
+// IP address, a CIDR range, a zone (*.example.com) or a host name
+// (localhost). A best effort is made to parse the string and errors are
+// ignored.
+func (p *proxy_PerHost) AddFromString(s string) {
+	hosts := strings.Split(s, ",")
+	for _, host := range hosts {
+		host = strings.TrimSpace(host)
+		if len(host) == 0 {
+			continue
+		}
+		if strings.Contains(host, "/") {
+			// We assume that it's a CIDR address like 127.0.0.0/8
+			if _, net, err := net.ParseCIDR(host); err == nil {
+				p.AddNetwork(net)
+			}
+			continue
+		}
+		if ip := net.ParseIP(host); ip != nil {
+			p.AddIP(ip)
+			continue
+		}
+		if strings.HasPrefix(host, "*.") {
+			p.AddZone(host[1:])
+			continue
+		}
+		p.AddHost(host)
+	}
+}
+
+// AddIP specifies an IP address that will use the bypass proxy. Note that
+// this will only take effect if a literal IP address is dialed. A connection
+// to a named host will never match an IP.
+func (p *proxy_PerHost) AddIP(ip net.IP) {
+	p.bypassIPs = append(p.bypassIPs, ip)
+}
+
+// AddNetwork specifies an IP range that will use the bypass proxy. Note that
+// this will only take effect if a literal IP address is dialed. A connection
+// to a named host will never match.
+func (p *proxy_PerHost) AddNetwork(net *net.IPNet) {
+	p.bypassNetworks = append(p.bypassNetworks, net)
+}
+
+// AddZone specifies a DNS suffix that will use the bypass proxy. A zone of
+// "example.com" matches "example.com" and all of its subdomains.
+func (p *proxy_PerHost) AddZone(zone string) {
+	if strings.HasSuffix(zone, ".") {
+		zone = zone[:len(zone)-1]
+	}
+	if !strings.HasPrefix(zone, ".") {
+		zone = "." + zone
+	}
+	p.bypassZones = append(p.bypassZones, zone)
+}
+
+// AddHost specifies a host name that will use the bypass proxy.
+func (p *proxy_PerHost) AddHost(host string) {
+	if strings.HasSuffix(host, ".") {
+		host = host[:len(host)-1]
+	}
+	p.bypassHosts = append(p.bypassHosts, host)
+}
+
+// A Dialer is a means to establish a connection.
+type proxy_Dialer interface {
+	// Dial connects to the given address via the proxy.
+	Dial(network, addr string) (c net.Conn, err error)
+}
+
+// Auth contains authentication parameters that specific Dialers may require.
+type proxy_Auth struct {
+	User, Password string
+}
+
+// FromEnvironment returns the dialer specified by the proxy related variables in
+// the environment.
+func proxy_FromEnvironment() proxy_Dialer {
+	allProxy := proxy_allProxyEnv.Get()
+	if len(allProxy) == 0 {
+		return proxy_Direct
+	}
+
+	proxyURL, err := url.Parse(allProxy)
+	if err != nil {
+		return proxy_Direct
+	}
+	proxy, err := proxy_FromURL(proxyURL, proxy_Direct)
+	if err != nil {
+		return proxy_Direct
+	}
+
+	noProxy := proxy_noProxyEnv.Get()
+	if len(noProxy) == 0 {
+		return proxy
+	}
+
+	perHost := proxy_NewPerHost(proxy, proxy_Direct)
+	perHost.AddFromString(noProxy)
+	return perHost
+}
+
+// proxySchemes is a map from URL schemes to a function that creates a Dialer
+// from a URL with such a scheme.
+var proxy_proxySchemes map[string]func(*url.URL, proxy_Dialer) (proxy_Dialer, error)
+
+// RegisterDialerType takes a URL scheme and a function to generate Dialers from
+// a URL with that scheme and a forwarding Dialer. Registered schemes are used
+// by FromURL.
+func proxy_RegisterDialerType(scheme string, f func(*url.URL, proxy_Dialer) (proxy_Dialer, error)) {
+	if proxy_proxySchemes == nil {
+		proxy_proxySchemes = make(map[string]func(*url.URL, proxy_Dialer) (proxy_Dialer, error))
+	}
+	proxy_proxySchemes[scheme] = f
+}
+
+// FromURL returns a Dialer given a URL specification and an underlying
+// Dialer for it to make network requests.
+func proxy_FromURL(u *url.URL, forward proxy_Dialer) (proxy_Dialer, error) {
+	var auth *proxy_Auth
+	if u.User != nil {
+		auth = new(proxy_Auth)
+		auth.User = u.User.Username()
+		if p, ok := u.User.Password(); ok {
+			auth.Password = p
+		}
+	}
+
+	switch u.Scheme {
+	case "socks5":
+		return proxy_SOCKS5("tcp", u.Host, auth, forward)
+	}
+
+	// If the scheme doesn't match any of the built-in schemes, see if it
+	// was registered by another package.
+	if proxy_proxySchemes != nil {
+		if f, ok := proxy_proxySchemes[u.Scheme]; ok {
+			return f(u, forward)
+		}
+	}
+
+	return nil, errors.New("proxy: unknown scheme: " + u.Scheme)
+}
+
+var (
+	proxy_allProxyEnv = &proxy_envOnce{
+		names: []string{"ALL_PROXY", "all_proxy"},
+	}
+	proxy_noProxyEnv = &proxy_envOnce{
+		names: []string{"NO_PROXY", "no_proxy"},
+	}
+)
+
+// envOnce looks up an environment variable (optionally by multiple
+// names) once. It mitigates expensive lookups on some platforms
+// (e.g. Windows).
+// (Borrowed from net/http/transport.go)
+type proxy_envOnce struct {
+	names []string
+	once  sync.Once
+	val   string
+}
+
+func (e *proxy_envOnce) Get() string {
+	e.once.Do(e.init)
+	return e.val
+}
+
+func (e *proxy_envOnce) init() {
+	for _, n := range e.names {
+		e.val = os.Getenv(n)
+		if e.val != "" {
+			return
+		}
+	}
+}
+
+// SOCKS5 returns a Dialer that makes SOCKSv5 connections to the given address
+// with an optional username and password. See RFC 1928 and RFC 1929.
+func proxy_SOCKS5(network, addr string, auth *proxy_Auth, forward proxy_Dialer) (proxy_Dialer, error) {
+	s := &proxy_socks5{
+		network: network,
+		addr:    addr,
+		forward: forward,
+	}
+	if auth != nil {
+		s.user = auth.User
+		s.password = auth.Password
+	}
+
+	return s, nil
+}
+
+type proxy_socks5 struct {
+	user, password string
+	network, addr  string
+	forward        proxy_Dialer
+}
+
+const proxy_socks5Version = 5
+
+const (
+	proxy_socks5AuthNone     = 0
+	proxy_socks5AuthPassword = 2
+)
+
+const proxy_socks5Connect = 1
+
+const (
+	proxy_socks5IP4    = 1
+	proxy_socks5Domain = 3
+	proxy_socks5IP6    = 4
+)
+
+var proxy_socks5Errors = []string{
+	"",
+	"general failure",
+	"connection forbidden",
+	"network unreachable",
+	"host unreachable",
+	"connection refused",
+	"TTL expired",
+	"command not supported",
+	"address type not supported",
+}
+
+// Dial connects to the address addr on the given network via the SOCKS5 proxy.
+func (s *proxy_socks5) Dial(network, addr string) (net.Conn, error) {
+	switch network {
+	case "tcp", "tcp6", "tcp4":
+	default:
+		return nil, errors.New("proxy: no support for SOCKS5 proxy connections of type " + network)
+	}
+
+	conn, err := s.forward.Dial(s.network, s.addr)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.connect(conn, addr); err != nil {
+		conn.Close()
+		return nil, err
+	}
+	return conn, nil
+}
+
+// connect takes an existing connection to a socks5 proxy server,
+// and commands the server to extend that connection to target,
+// which must be a canonical address with a host and port.
+func (s *proxy_socks5) connect(conn net.Conn, target string) error {
+	host, portStr, err := net.SplitHostPort(target)
+	if err != nil {
+		return err
+	}
+
+	port, err := strconv.Atoi(portStr)
+	if err != nil {
+		return errors.New("proxy: failed to parse port number: " + portStr)
+	}
+	if port < 1 || port > 0xffff {
+		return errors.New("proxy: port number out of range: " + portStr)
+	}
+
+	// the size here is just an estimate
+	buf := make([]byte, 0, 6+len(host))
+
+	buf = append(buf, proxy_socks5Version)
+	if len(s.user) > 0 && len(s.user) < 256 && len(s.password) < 256 {
+		buf = append(buf, 2 /* num auth methods */, proxy_socks5AuthNone, proxy_socks5AuthPassword)
+	} else {
+		buf = append(buf, 1 /* num auth methods */, proxy_socks5AuthNone)
+	}
+
+	if _, err := conn.Write(buf); err != nil {
+		return errors.New("proxy: failed to write greeting to SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	if _, err := io.ReadFull(conn, buf[:2]); err != nil {
+		return errors.New("proxy: failed to read greeting from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+	if buf[0] != 5 {
+		return errors.New("proxy: SOCKS5 proxy at " + s.addr + " has unexpected version " + strconv.Itoa(int(buf[0])))
+	}
+	if buf[1] == 0xff {
+		return errors.New("proxy: SOCKS5 proxy at " + s.addr + " requires authentication")
+	}
+
+	// See RFC 1929
+	if buf[1] == proxy_socks5AuthPassword {
+		buf = buf[:0]
+		buf = append(buf, 1 /* password protocol version */)
+		buf = append(buf, uint8(len(s.user)))
+		buf = append(buf, s.user...)
+		buf = append(buf, uint8(len(s.password)))
+		buf = append(buf, s.password...)
+
+		if _, err := conn.Write(buf); err != nil {
+			return errors.New("proxy: failed to write authentication request to SOCKS5 proxy at " + s.addr + ": " + err.Error())
+		}
+
+		if _, err := io.ReadFull(conn, buf[:2]); err != nil {
+			return errors.New("proxy: failed to read authentication reply from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+		}
+
+		if buf[1] != 0 {
+			return errors.New("proxy: SOCKS5 proxy at " + s.addr + " rejected username/password")
+		}
+	}
+
+	buf = buf[:0]
+	buf = append(buf, proxy_socks5Version, proxy_socks5Connect, 0 /* reserved */)
+
+	if ip := net.ParseIP(host); ip != nil {
+		if ip4 := ip.To4(); ip4 != nil {
+			buf = append(buf, proxy_socks5IP4)
+			ip = ip4
+		} else {
+			buf = append(buf, proxy_socks5IP6)
+		}
+		buf = append(buf, ip...)
+	} else {
+		if len(host) > 255 {
+			return errors.New("proxy: destination host name too long: " + host)
+		}
+		buf = append(buf, proxy_socks5Domain)
+		buf = append(buf, byte(len(host)))
+		buf = append(buf, host...)
+	}
+	buf = append(buf, byte(port>>8), byte(port))
+
+	if _, err := conn.Write(buf); err != nil {
+		return errors.New("proxy: failed to write connect request to SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	if _, err := io.ReadFull(conn, buf[:4]); err != nil {
+		return errors.New("proxy: failed to read connect reply from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	failure := "unknown error"
+	if int(buf[1]) < len(proxy_socks5Errors) {
+		failure = proxy_socks5Errors[buf[1]]
+	}
+
+	if len(failure) > 0 {
+		return errors.New("proxy: SOCKS5 proxy at " + s.addr + " failed to connect: " + failure)
+	}
+
+	bytesToDiscard := 0
+	switch buf[3] {
+	case proxy_socks5IP4:
+		bytesToDiscard = net.IPv4len
+	case proxy_socks5IP6:
+		bytesToDiscard = net.IPv6len
+	case proxy_socks5Domain:
+		_, err := io.ReadFull(conn, buf[:1])
+		if err != nil {
+			return errors.New("proxy: failed to read domain length from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+		}
+		bytesToDiscard = int(buf[0])
+	default:
+		return errors.New("proxy: got unknown address type " + strconv.Itoa(int(buf[3])) + " from SOCKS5 proxy at " + s.addr)
+	}
+
+	if cap(buf) < bytesToDiscard {
+		buf = make([]byte, bytesToDiscard)
+	} else {
+		buf = buf[:bytesToDiscard]
+	}
+	if _, err := io.ReadFull(conn, buf); err != nil {
+		return errors.New("proxy: failed to read address from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	// Also need to discard the port number
+	if _, err := io.ReadFull(conn, buf[:2]); err != nil {
+		return errors.New("proxy: failed to read port from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	return nil
+}

backend/vendor/github.com/slack-go/slack/.gitignore

@@ -0,0 +1,3 @@
+*.test
+*~
+.idea/

backend/vendor/github.com/slack-go/slack/.golangci.yml

@@ -0,0 +1,14 @@
+run:
+  timeout: 6m
+  issues-exit-code: 1
+linters:
+  disable-all: true
+  enable:
+    - goimports
+    - govet
+    - interfacer
+    - misspell
+    - structcheck
+    - unconvert
+issues:
+  new: true

backend/vendor/github.com/slack-go/slack/CHANGELOG.md

@@ -0,0 +1,103 @@
+### v0.7.0 - October 2, 2020
+full differences can be viewed using `git log --oneline --decorate --color v0.6.6..v0.7.0`
+Thank you for many contributions!
+
+#### Breaking Changes
+- Add ScheduledMessage type ([#753])
+- Add description field to option block object ([#783])
+- Fix wrong conditional branch ([#782])
+  - The behavior of the user's application may change.(The current behavior is incorrect)
+
+#### Highlights
+- example: fix to start up a server ([#773])
+- example: Add explanation how the message could be sent in a proper way ([#787])
+- example: fix typo in error log ([#779])
+- refactor: Make GetConversationsParameters.ExcludeArchived optional ([#791])
+- refactor: Unify variables to "config" ([#800])
+- refactor: Rename wrong file name ([#810])
+- feature: Add SetUserRealName for change user's realName([#755])
+- feature: Add response metadata to slack response ([#772])
+- feature: Add response metadata to slack response ([#778])
+- feature: Add select block element conversations filter field ([#790])
+- feature: Add Root field to MessageEvent to support thread_broadcast subtype ([#793])
+- feature: Add bot_profile to messages ([#794])
+- doc: Add logo to README ([#813])
+- doc: Update current project status and Add changelog for v0.7.0 ([#814])
+
+[#753]: https://github.com/slack-go/slack/pull/753
+[#755]: https://github.com/slack-go/slack/pull/755
+[#772]: https://github.com/slack-go/slack/pull/772
+[#773]: https://github.com/slack-go/slack/pull/773
+[#778]: https://github.com/slack-go/slack/pull/778
+[#779]: https://github.com/slack-go/slack/pull/779
+[#782]: https://github.com/slack-go/slack/pull/782
+[#783]: https://github.com/slack-go/slack/pull/783
+[#787]: https://github.com/slack-go/slack/pull/787
+[#790]: https://github.com/slack-go/slack/pull/790
+[#791]: https://github.com/slack-go/slack/pull/791
+[#793]: https://github.com/slack-go/slack/pull/793
+[#794]: https://github.com/slack-go/slack/pull/794
+[#800]: https://github.com/slack-go/slack/pull/800
+[#810]: https://github.com/slack-go/slack/pull/810
+[#813]: https://github.com/slack-go/slack/pull/813
+[#814]: https://github.com/slack-go/slack/pull/814
+
+### v0.6.0 - August 31, 2019
+full differences can be viewed using `git log --oneline --decorate --color v0.5.0..v0.6.0`
+thanks to everyone who has contributed since January!
+
+
+#### Breaking Changes:
+- Info struct has had fields removed related to deprecated functionality by slack.
+- minor adjustments to some structs.
+- some internal default values have changed, usually to be more inline with slack defaults or to correct inability to set a particular value. (Message Parse for example.)
+
+##### Highlights:
+- new slacktest package easy mocking for slack client. use, enjoy, please submit PRs for improvements and default behaviours! shamelessly taken from the [slack-test repo](https://github.com/lusis/slack-test) thank you lusis for letting us use it and bring it into the slack repo.
+- blocks, blocks, blocks.
+- RTM ManagedConnection has undergone a significant cleanup.
+in particular handles backoffs gracefully, removed many deadlocks,
+and Disconnect is now much more responsive.
+
+### v0.5.0 - January 20, 2019
+full differences can be viewed using `git log --oneline --decorate --color v0.4.0..v0.5.0`
+- Breaking changes: various old struct fields have been removed or updated to match slack's api.
+- deadlock fix in RTM disconnect.
+
+### v0.4.0 - October 06, 2018
+full differences can be viewed using `git log --oneline --decorate --color v0.3.0..v0.4.0`
+- Breaking Change: renamed ApplyMessageOption, to mark it as unsafe,
+this means it may break without warning in the future.
+- Breaking: Msg structure files field changed to an array.
+- General: implementation for new security headers.
+- RTM: deadlock fix between connect/disconnect.
+- Events: various new fields added.
+- Web: various fixes, new fields exposed, new methods added.
+- Interactions: minor additions expect breaking changes in next release for dialogs/button clicks.
+- Utils: new methods added.
+
+### v0.3.0 - July 30, 2018
+full differences can be viewed using `git log --oneline --decorate --color v0.2.0..v0.3.0`
+- slack events initial support added. (still considered experimental and undergoing changes, stability not promised)
+- vendored depedencies using dep, ensure using up to date tooling before filing issues.
+- RTM has improved its ability to identify dead connections and reconnect automatically (worth calling out in case it has unintended side effects).
+- bug fixes (various timestamp handling, error handling, RTM locking, etc).
+
+### v0.2.0 - Feb 10, 2018
+
+Release adds a bunch of functionality and improvements, mainly to give people a recent version to vendor against.
+
+Please check [0.2.0](https://github.com/nlopes/slack/releases/tag/v0.2.0)
+
+### v0.1.0 - May 28, 2017
+
+This is released before adding context support.
+As the used context package is the one from Go 1.7 this will be the last
+compatible with Go < 1.7.
+
+Please check [0.1.0](https://github.com/nlopes/slack/releases/tag/v0.1.0)
+
+### v0.0.1 - Jul 26, 2015
+
+If you just updated from master and it broke your implementation, please
+check [0.0.1](https://github.com/nlopes/slack/releases/tag/v0.0.1)

backend/vendor/github.com/slack-go/slack/LICENSE

@@ -0,0 +1,23 @@
+Copyright (c) 2015, Norberto Lopes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation and/or
+other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

backend/vendor/github.com/slack-go/slack/Makefile

@@ -0,0 +1,36 @@
+.PHONY: help deps fmt lint test test-race test-integration
+
+help:
+	@echo ""
+	@echo "Welcome to slack-go/slack make."
+	@echo "The following commands are available:"
+	@echo ""
+	@echo "    make deps              : Fetch all dependencies"
+	@echo "    make fmt               : Run go fmt to fix any formatting issues"
+	@echo "    make lint              : Use go vet to check for linting issues"
+	@echo "    make test              : Run all short tests"
+	@echo "    make test-race         : Run all tests with race condition checking"
+	@echo "    make test-integration  : Run all tests without limiting to short"
+	@echo ""
+	@echo "    make pr-prep           : Run this before making a PR to run fmt, lint and tests"
+	@echo ""
+
+deps:
+	@go mod tidy
+
+fmt:
+	@go fmt .
+
+lint:
+	@go vet .
+
+test:
+	@go test -v -count=1 -timeout 300s -short ./...
+
+test-race:
+	@go test -v -count=1 -timeout 300s -short -race ./...
+
+test-integration:
+	@go test -v -count=1 -timeout 600s ./...
+
+pr-prep: fmt lint test-race test-integration

backend/vendor/github.com/slack-go/slack/README.md

@@ -0,0 +1,97 @@
+Slack API in Go [![GoDoc](https://godoc.org/github.com/slack-go/slack?status.svg)](https://godoc.org/github.com/slack-go/slack) [![Build Status](https://travis-ci.org/slack-go/slack.svg)](https://travis-ci.org/slack-go/slack)
+===============
+This is the original Slack library for Go created by Norberto Lopes, transferred to a Github organization.
+
+[![Join the chat at https://gitter.im/go-slack/Lobby](https://badges.gitter.im/go-slack/Lobby.svg)](https://gitter.im/go-slack/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+
+![logo](logo.png "icon")
+
+This library supports most if not all of the `api.slack.com` REST
+calls, as well as the Real-Time Messaging protocol over websocket, in
+a fully managed way.
+
+## Project Status
+There is currently no major version released.
+Therefore, minor version releases may include backward incompatible changes.
+
+See [CHANGELOG.md](https://github.com/slack-go/slack/blob/master/CHANGELOG.md) for more information about the changes.
+
+## Installing
+
+### *go get*
+
+    $ go get -u github.com/slack-go/slack
+
+## Example
+
+### Getting all groups
+
+```golang
+import (
+	"fmt"
+
+	"github.com/slack-go/slack"
+)
+
+func main() {
+	api := slack.New("YOUR_TOKEN_HERE")
+	// If you set debugging, it will log all requests to the console
+	// Useful when encountering issues
+	// slack.New("YOUR_TOKEN_HERE", slack.OptionDebug(true))
+	groups, err := api.GetGroups(false)
+	if err != nil {
+		fmt.Printf("%s\n", err)
+		return
+	}
+	for _, group := range groups {
+		fmt.Printf("ID: %s, Name: %s\n", group.ID, group.Name)
+	}
+}
+```
+
+### Getting User Information
+
+```golang
+import (
+    "fmt"
+
+    "github.com/slack-go/slack"
+)
+
+func main() {
+    api := slack.New("YOUR_TOKEN_HERE")
+    user, err := api.GetUserInfo("U023BECGF")
+    if err != nil {
+	    fmt.Printf("%s\n", err)
+	    return
+    }
+    fmt.Printf("ID: %s, Fullname: %s, Email: %s\n", user.ID, user.Profile.RealName, user.Profile.Email)
+}
+```
+
+## Minimal RTM usage:
+
+See https://github.com/slack-go/slack/blob/master/examples/websocket/websocket.go
+
+
+## Minimal EventsAPI usage:
+
+See https://github.com/slack-go/slack/blob/master/examples/eventsapi/events.go
+
+
+## Contributing
+
+You are more than welcome to contribute to this project.  Fork and
+make a Pull Request, or create an Issue if you see any problem.
+
+Before making any Pull Request please run the following:
+
+```
+make pr-prep
+```
+
+This will check/update code formatting, linting and then run all tests
+
+## License
+
+BSD 2 Clause license

backend/vendor/github.com/slack-go/slack/TODO.txt

@@ -0,0 +1,3 @@
+- Add more tests!!!
+- Add support to have markdown hints
+  - See section Message Formatting at https://api.slack.com/docs/formatting

backend/vendor/github.com/slack-go/slack/admin.go

@@ -0,0 +1,207 @@
+package slack
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+	"strings"
+)
+
+func (api *Client) adminRequest(ctx context.Context, method string, teamName string, values url.Values) error {
+	resp := &SlackResponse{}
+	err := parseAdminResponse(ctx, api.httpclient, method, teamName, values, resp, api)
+	if err != nil {
+		return err
+	}
+
+	return resp.Err()
+}
+
+// DisableUser disabled a user account, given a user ID
+func (api *Client) DisableUser(teamName string, uid string) error {
+	return api.DisableUserContext(context.Background(), teamName, uid)
+}
+
+// DisableUserContext disabled a user account, given a user ID with a custom context
+func (api *Client) DisableUserContext(ctx context.Context, teamName string, uid string) error {
+	values := url.Values{
+		"user":       {uid},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	if err := api.adminRequest(ctx, "setInactive", teamName, values); err != nil {
+		return fmt.Errorf("failed to disable user with id '%s': %s", uid, err)
+	}
+
+	return nil
+}
+
+// InviteGuest invites a user to Slack as a single-channel guest
+func (api *Client) InviteGuest(teamName, channel, firstName, lastName, emailAddress string) error {
+	return api.InviteGuestContext(context.Background(), teamName, channel, firstName, lastName, emailAddress)
+}
+
+// InviteGuestContext invites a user to Slack as a single-channel guest with a custom context
+func (api *Client) InviteGuestContext(ctx context.Context, teamName, channel, firstName, lastName, emailAddress string) error {
+	values := url.Values{
+		"email":            {emailAddress},
+		"channels":         {channel},
+		"first_name":       {firstName},
+		"last_name":        {lastName},
+		"ultra_restricted": {"1"},
+		"token":            {api.token},
+		"resend":           {"true"},
+		"set_active":       {"true"},
+		"_attempts":        {"1"},
+	}
+
+	err := api.adminRequest(ctx, "invite", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to invite single-channel guest: %s", err)
+	}
+
+	return nil
+}
+
+// InviteRestricted invites a user to Slack as a restricted account
+func (api *Client) InviteRestricted(teamName, channel, firstName, lastName, emailAddress string) error {
+	return api.InviteRestrictedContext(context.Background(), teamName, channel, firstName, lastName, emailAddress)
+}
+
+// InviteRestrictedContext invites a user to Slack as a restricted account with a custom context
+func (api *Client) InviteRestrictedContext(ctx context.Context, teamName, channel, firstName, lastName, emailAddress string) error {
+	values := url.Values{
+		"email":      {emailAddress},
+		"channels":   {channel},
+		"first_name": {firstName},
+		"last_name":  {lastName},
+		"restricted": {"1"},
+		"token":      {api.token},
+		"resend":     {"true"},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "invite", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to restricted account: %s", err)
+	}
+
+	return nil
+}
+
+// InviteToTeam invites a user to a Slack team
+func (api *Client) InviteToTeam(teamName, firstName, lastName, emailAddress string) error {
+	return api.InviteToTeamContext(context.Background(), teamName, firstName, lastName, emailAddress)
+}
+
+// InviteToTeamContext invites a user to a Slack team with a custom context
+func (api *Client) InviteToTeamContext(ctx context.Context, teamName, firstName, lastName, emailAddress string) error {
+	values := url.Values{
+		"email":      {emailAddress},
+		"first_name": {firstName},
+		"last_name":  {lastName},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "invite", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to invite to team: %s", err)
+	}
+
+	return nil
+}
+
+// SetRegular enables the specified user
+func (api *Client) SetRegular(teamName, user string) error {
+	return api.SetRegularContext(context.Background(), teamName, user)
+}
+
+// SetRegularContext enables the specified user with a custom context
+func (api *Client) SetRegularContext(ctx context.Context, teamName, user string) error {
+	values := url.Values{
+		"user":       {user},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "setRegular", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to change the user (%s) to a regular user: %s", user, err)
+	}
+
+	return nil
+}
+
+// SendSSOBindingEmail sends an SSO binding email to the specified user
+func (api *Client) SendSSOBindingEmail(teamName, user string) error {
+	return api.SendSSOBindingEmailContext(context.Background(), teamName, user)
+}
+
+// SendSSOBindingEmailContext sends an SSO binding email to the specified user with a custom context
+func (api *Client) SendSSOBindingEmailContext(ctx context.Context, teamName, user string) error {
+	values := url.Values{
+		"user":       {user},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "sendSSOBind", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to send SSO binding email for user (%s): %s", user, err)
+	}
+
+	return nil
+}
+
+// SetUltraRestricted converts a user into a single-channel guest
+func (api *Client) SetUltraRestricted(teamName, uid, channel string) error {
+	return api.SetUltraRestrictedContext(context.Background(), teamName, uid, channel)
+}
+
+// SetUltraRestrictedContext converts a user into a single-channel guest with a custom context
+func (api *Client) SetUltraRestrictedContext(ctx context.Context, teamName, uid, channel string) error {
+	values := url.Values{
+		"user":       {uid},
+		"channel":    {channel},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "setUltraRestricted", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to ultra-restrict account: %s", err)
+	}
+
+	return nil
+}
+
+// SetRestricted converts a user into a restricted account
+func (api *Client) SetRestricted(teamName, uid string, channelIds ...string) error {
+	return api.SetRestrictedContext(context.Background(), teamName, uid, channelIds...)
+}
+
+// SetRestrictedContext converts a user into a restricted account with a custom context
+func (api *Client) SetRestrictedContext(ctx context.Context, teamName, uid string, channelIds ...string) error {
+	values := url.Values{
+		"user":       {uid},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+		"channels":   {strings.Join(channelIds, ",")},
+	}
+
+	err := api.adminRequest(ctx, "setRestricted", teamName, values)
+	if err != nil {
+		return fmt.Errorf("failed to restrict account: %s", err)
+	}
+
+	return nil
+}

backend/vendor/github.com/slack-go/slack/apps.go

@@ -0,0 +1,61 @@
+package slack
+
+import (
+	"context"
+	"encoding/json"
+	"net/url"
+)
+
+type listEventAuthorizationsResponse struct {
+	SlackResponse
+	Authorizations []EventAuthorization `json:"authorizations"`
+}
+
+type EventAuthorization struct {
+	EnterpriseID        string `json:"enterprise_id"`
+	TeamID              string `json:"team_id"`
+	UserID              string `json:"user_id"`
+	IsBot               bool   `json:"is_bot"`
+	IsEnterpriseInstall bool   `json:"is_enterprise_install"`
+}
+
+func (api *Client) ListEventAuthorizations(eventContext string) ([]EventAuthorization, error) {
+	return api.ListEventAuthorizationsContext(context.Background(), eventContext)
+}
+
+// ListEventAuthorizationsContext lists authed users and teams for the given event_context. You must provide an app-level token to the client using OptionAppLevelToken. More info: https://api.slack.com/methods/apps.event.authorizations.list
+func (api *Client) ListEventAuthorizationsContext(ctx context.Context, eventContext string) ([]EventAuthorization, error) {
+	resp := &listEventAuthorizationsResponse{}
+
+	request, _ := json.Marshal(map[string]string{
+		"event_context": eventContext,
+	})
+
+	err := postJSON(ctx, api.httpclient, api.endpoint+"apps.event.authorizations.list", api.appLevelToken, request, &resp, api)
+
+	if err != nil {
+		return nil, err
+	}
+	if !resp.Ok {
+		return nil, resp.Err()
+	}
+
+	return resp.Authorizations, nil
+}
+
+func (api *Client) UninstallApp(clientID, clientSecret string) error {
+	values := url.Values{
+		"token":         {api.token},
+		"client_id":     {clientID},
+		"client_secret": {clientSecret},
+	}
+
+	response := SlackResponse{}
+
+	err := api.getMethod(context.Background(), "apps.uninstall", values, &response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}

backend/vendor/github.com/slack-go/slack/attachments.go

@@ -0,0 +1,98 @@
+package slack
+
+import "encoding/json"
+
+// AttachmentField contains information for an attachment field
+// An Attachment can contain multiple of these
+type AttachmentField struct {
+	Title string `json:"title"`
+	Value string `json:"value"`
+	Short bool   `json:"short"`
+}
+
+// AttachmentAction is a button or menu to be included in the attachment. Required when
+// using message buttons or menus and otherwise not useful. A maximum of 5 actions may be
+// provided per attachment.
+type AttachmentAction struct {
+	Name            string                        `json:"name"`                       // Required.
+	Text            string                        `json:"text"`                       // Required.
+	Style           string                        `json:"style,omitempty"`            // Optional. Allowed values: "default", "primary", "danger".
+	Type            actionType                    `json:"type"`                       // Required. Must be set to "button" or "select".
+	Value           string                        `json:"value,omitempty"`            // Optional.
+	DataSource      string                        `json:"data_source,omitempty"`      // Optional.
+	MinQueryLength  int                           `json:"min_query_length,omitempty"` // Optional. Default value is 1.
+	Options         []AttachmentActionOption      `json:"options,omitempty"`          // Optional. Maximum of 100 options can be provided in each menu.
+	SelectedOptions []AttachmentActionOption      `json:"selected_options,omitempty"` // Optional. The first element of this array will be set as the pre-selected option for this menu.
+	OptionGroups    []AttachmentActionOptionGroup `json:"option_groups,omitempty"`    // Optional.
+	Confirm         *ConfirmationField            `json:"confirm,omitempty"`          // Optional.
+	URL             string                        `json:"url,omitempty"`              // Optional.
+}
+
+// actionType returns the type of the action
+func (a AttachmentAction) actionType() actionType {
+	return a.Type
+}
+
+// AttachmentActionOption the individual option to appear in action menu.
+type AttachmentActionOption struct {
+	Text        string `json:"text"`                  // Required.
+	Value       string `json:"value"`                 // Required.
+	Description string `json:"description,omitempty"` // Optional. Up to 30 characters.
+}
+
+// AttachmentActionOptionGroup is a semi-hierarchal way to list available options to appear in action menu.
+type AttachmentActionOptionGroup struct {
+	Text    string                   `json:"text"`    // Required.
+	Options []AttachmentActionOption `json:"options"` // Required.
+}
+
+// AttachmentActionCallback is sent from Slack when a user clicks a button in an interactive message (aka AttachmentAction)
+// DEPRECATED: use InteractionCallback
+type AttachmentActionCallback InteractionCallback
+
+// ConfirmationField are used to ask users to confirm actions
+type ConfirmationField struct {
+	Title       string `json:"title,omitempty"`        // Optional.
+	Text        string `json:"text"`                   // Required.
+	OkText      string `json:"ok_text,omitempty"`      // Optional. Defaults to "Okay"
+	DismissText string `json:"dismiss_text,omitempty"` // Optional. Defaults to "Cancel"
+}
+
+// Attachment contains all the information for an attachment
+type Attachment struct {
+	Color    string `json:"color,omitempty"`
+	Fallback string `json:"fallback,omitempty"`
+
+	CallbackID string `json:"callback_id,omitempty"`
+	ID         int    `json:"id,omitempty"`
+
+	AuthorID      string `json:"author_id,omitempty"`
+	AuthorName    string `json:"author_name,omitempty"`
+	AuthorSubname string `json:"author_subname,omitempty"`
+	AuthorLink    string `json:"author_link,omitempty"`
+	AuthorIcon    string `json:"author_icon,omitempty"`
+
+	Title     string `json:"title,omitempty"`
+	TitleLink string `json:"title_link,omitempty"`
+	Pretext   string `json:"pretext,omitempty"`
+	Text      string `json:"text,omitempty"`
+
+	ImageURL string `json:"image_url,omitempty"`
+	ThumbURL string `json:"thumb_url,omitempty"`
+
+	ServiceName string `json:"service_name,omitempty"`
+	ServiceIcon string `json:"service_icon,omitempty"`
+	FromURL     string `json:"from_url,omitempty"`
+	OriginalURL string `json:"original_url,omitempty"`
+
+	Fields     []AttachmentField  `json:"fields,omitempty"`
+	Actions    []AttachmentAction `json:"actions,omitempty"`
+	MarkdownIn []string           `json:"mrkdwn_in,omitempty"`
+
+	Blocks Blocks `json:"blocks,omitempty"`
+
+	Footer     string `json:"footer,omitempty"`
+	FooterIcon string `json:"footer_icon,omitempty"`
+
+	Ts json.Number `json:"ts,omitempty"`
+}

backend/vendor/github.com/slack-go/slack/auth.go

@@ -0,0 +1,40 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+// AuthRevokeResponse contains our Auth response from the auth.revoke endpoint
+type AuthRevokeResponse struct {
+	SlackResponse      // Contains the "ok", and "Error", if any
+	Revoked       bool `json:"revoked,omitempty"`
+}
+
+// authRequest sends the actual request, and unmarshals the response
+func (api *Client) authRequest(ctx context.Context, path string, values url.Values) (*AuthRevokeResponse, error) {
+	response := &AuthRevokeResponse{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// SendAuthRevoke will send a revocation for our token
+func (api *Client) SendAuthRevoke(token string) (*AuthRevokeResponse, error) {
+	return api.SendAuthRevokeContext(context.Background(), token)
+}
+
+// SendAuthRevokeContext will send a revocation request for our token to api.revoke with context
+func (api *Client) SendAuthRevokeContext(ctx context.Context, token string) (*AuthRevokeResponse, error) {
+	if token == "" {
+		token = api.token
+	}
+	values := url.Values{
+		"token": {token},
+	}
+
+	return api.authRequest(ctx, "auth.revoke", values)
+}

backend/vendor/github.com/slack-go/slack/block.go

@@ -0,0 +1,80 @@
+package slack
+
+// @NOTE: Blocks are in beta and subject to change.
+
+// More Information: https://api.slack.com/block-kit
+
+// MessageBlockType defines a named string type to define each block type
+// as a constant for use within the package.
+type MessageBlockType string
+
+const (
+	MBTSection MessageBlockType = "section"
+	MBTDivider MessageBlockType = "divider"
+	MBTImage   MessageBlockType = "image"
+	MBTAction  MessageBlockType = "actions"
+	MBTContext MessageBlockType = "context"
+	MBTFile    MessageBlockType = "file"
+	MBTInput   MessageBlockType = "input"
+	MBTHeader  MessageBlockType = "header"
+)
+
+// Block defines an interface all block types should implement
+// to ensure consistency between blocks.
+type Block interface {
+	BlockType() MessageBlockType
+}
+
+// Blocks is a convenience struct defined to allow dynamic unmarshalling of
+// the "blocks" value in Slack's JSON response, which varies depending on block type
+type Blocks struct {
+	BlockSet []Block `json:"blocks,omitempty"`
+}
+
+// BlockAction is the action callback sent when a block is interacted with
+type BlockAction struct {
+	ActionID              string              `json:"action_id"`
+	BlockID               string              `json:"block_id"`
+	Type                  actionType          `json:"type"`
+	Text                  TextBlockObject     `json:"text"`
+	Value                 string              `json:"value"`
+	ActionTs              string              `json:"action_ts"`
+	SelectedOption        OptionBlockObject   `json:"selected_option"`
+	SelectedOptions       []OptionBlockObject `json:"selected_options"`
+	SelectedUser          string              `json:"selected_user"`
+	SelectedUsers         []string            `json:"selected_users"`
+	SelectedChannel       string              `json:"selected_channel"`
+	SelectedChannels      []string            `json:"selected_channels"`
+	SelectedConversation  string              `json:"selected_conversation"`
+	SelectedConversations []string            `json:"selected_conversations"`
+	SelectedDate          string              `json:"selected_date"`
+	SelectedTime          string              `json:"selected_time"`
+	InitialOption         OptionBlockObject   `json:"initial_option"`
+	InitialUser           string              `json:"initial_user"`
+	InitialChannel        string              `json:"initial_channel"`
+	InitialConversation   string              `json:"initial_conversation"`
+	InitialDate           string              `json:"initial_date"`
+	InitialTime           string              `json:"initial_time"`
+}
+
+// actionType returns the type of the action
+func (b BlockAction) actionType() actionType {
+	return b.Type
+}
+
+// NewBlockMessage creates a new Message that contains one or more blocks to be displayed
+func NewBlockMessage(blocks ...Block) Message {
+	return Message{
+		Msg: Msg{
+			Blocks: Blocks{
+				BlockSet: blocks,
+			},
+		},
+	}
+}
+
+// AddBlockMessage appends a block to the end of the existing list of blocks
+func AddBlockMessage(message Message, newBlk Block) Message {
+	message.Msg.Blocks.BlockSet = append(message.Msg.Blocks.BlockSet, newBlk)
+	return message
+}

backend/vendor/github.com/slack-go/slack/block_action.go

@@ -0,0 +1,26 @@
+package slack
+
+// ActionBlock defines data that is used to hold interactive elements.
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#actions
+type ActionBlock struct {
+	Type     MessageBlockType `json:"type"`
+	BlockID  string           `json:"block_id,omitempty"`
+	Elements *BlockElements   `json:"elements"`
+}
+
+// BlockType returns the type of the block
+func (s ActionBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewActionBlock returns a new instance of an Action Block
+func NewActionBlock(blockID string, elements ...BlockElement) *ActionBlock {
+	return &ActionBlock{
+		Type:    MBTAction,
+		BlockID: blockID,
+		Elements: &BlockElements{
+			ElementSet: elements,
+		},
+	}
+}

backend/vendor/github.com/slack-go/slack/block_context.go

@@ -0,0 +1,32 @@
+package slack
+
+// ContextBlock defines data that is used to display message context, which can
+// include both images and text.
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#actions
+type ContextBlock struct {
+	Type            MessageBlockType `json:"type"`
+	BlockID         string           `json:"block_id,omitempty"`
+	ContextElements ContextElements  `json:"elements"`
+}
+
+// BlockType returns the type of the block
+func (s ContextBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+type ContextElements struct {
+	Elements []MixedElement
+}
+
+// NewContextBlock returns a new instance of a context block
+func NewContextBlock(blockID string, mixedElements ...MixedElement) *ContextBlock {
+	elements := ContextElements{
+		Elements: mixedElements,
+	}
+	return &ContextBlock{
+		Type:            MBTContext,
+		BlockID:         blockID,
+		ContextElements: elements,
+	}
+}

backend/vendor/github.com/slack-go/slack/block_conv.go

@@ -0,0 +1,417 @@
+package slack
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/pkg/errors"
+)
+
+type sumtype struct {
+	TypeVal string `json:"type"`
+}
+
+// MarshalJSON implements the Marshaller interface for Blocks so that any JSON
+// marshalling is delegated and proper type determination can be made before marshal
+func (b Blocks) MarshalJSON() ([]byte, error) {
+	bytes, err := json.Marshal(b.BlockSet)
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes, nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for Blocks, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (b *Blocks) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+
+	if string(data) == "{}" {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	var blocks Blocks
+	for _, r := range raw {
+		s := sumtype{}
+		err := json.Unmarshal(r, &s)
+		if err != nil {
+			return err
+		}
+
+		var blockType string
+		if s.TypeVal != "" {
+			blockType = s.TypeVal
+		}
+
+		var block Block
+		switch blockType {
+		case "actions":
+			block = &ActionBlock{}
+		case "context":
+			block = &ContextBlock{}
+		case "divider":
+			block = &DividerBlock{}
+		case "file":
+			block = &FileBlock{}
+		case "header":
+			block = &HeaderBlock{}
+		case "image":
+			block = &ImageBlock{}
+		case "input":
+			block = &InputBlock{}
+		case "section":
+			block = &SectionBlock{}
+		default:
+			block = &UnknownBlock{}
+		}
+
+		err = json.Unmarshal(r, block)
+		if err != nil {
+			return err
+		}
+
+		blocks.BlockSet = append(blocks.BlockSet, block)
+	}
+
+	*b = blocks
+	return nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for InputBlock, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (b *InputBlock) UnmarshalJSON(data []byte) error {
+	type alias InputBlock
+	a := struct {
+		Element json.RawMessage `json:"element"`
+		*alias
+	}{
+		alias: (*alias)(b),
+	}
+
+	if err := json.Unmarshal(data, &a); err != nil {
+		return err
+	}
+
+	s := sumtype{}
+	if err := json.Unmarshal(a.Element, &s); err != nil {
+		return nil
+	}
+
+	var e BlockElement
+	switch s.TypeVal {
+	case "datepicker":
+		e = &DatePickerBlockElement{}
+	case "timepicker":
+		e = &TimePickerBlockElement{}
+	case "plain_text_input":
+		e = &PlainTextInputBlockElement{}
+	case "static_select", "external_select", "users_select", "conversations_select", "channels_select":
+		e = &SelectBlockElement{}
+	case "multi_static_select", "multi_external_select", "multi_users_select", "multi_conversations_select", "multi_channels_select":
+		e = &MultiSelectBlockElement{}
+	case "checkboxes":
+		e = &CheckboxGroupsBlockElement{}
+	case "overflow":
+		e = &OverflowBlockElement{}
+	case "radio_buttons":
+		e = &RadioButtonsBlockElement{}
+	default:
+		return errors.New("unsupported block element type")
+	}
+
+	if err := json.Unmarshal(a.Element, e); err != nil {
+		return err
+	}
+	b.Element = e
+
+	return nil
+}
+
+// MarshalJSON implements the Marshaller interface for BlockElements so that any JSON
+// marshalling is delegated and proper type determination can be made before marshal
+func (b *BlockElements) MarshalJSON() ([]byte, error) {
+	bytes, err := json.Marshal(b.ElementSet)
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes, nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for BlockElements, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (b *BlockElements) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+
+	if string(data) == "{}" {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	var blockElements BlockElements
+	for _, r := range raw {
+		s := sumtype{}
+		err := json.Unmarshal(r, &s)
+		if err != nil {
+			return err
+		}
+
+		var blockElementType string
+		if s.TypeVal != "" {
+			blockElementType = s.TypeVal
+		}
+
+		var blockElement BlockElement
+		switch blockElementType {
+		case "image":
+			blockElement = &ImageBlockElement{}
+		case "button":
+			blockElement = &ButtonBlockElement{}
+		case "overflow":
+			blockElement = &OverflowBlockElement{}
+		case "datepicker":
+			blockElement = &DatePickerBlockElement{}
+		case "plain_text_input":
+			blockElement = &PlainTextInputBlockElement{}
+		case "checkboxes":
+			blockElement = &CheckboxGroupsBlockElement{}
+		case "radio_buttons":
+			blockElement = &RadioButtonsBlockElement{}
+		case "static_select", "external_select", "users_select", "conversations_select", "channels_select":
+			blockElement = &SelectBlockElement{}
+		default:
+			return fmt.Errorf("unsupported block element type %v", blockElementType)
+		}
+
+		err = json.Unmarshal(r, blockElement)
+		if err != nil {
+			return err
+		}
+
+		blockElements.ElementSet = append(blockElements.ElementSet, blockElement)
+	}
+
+	*b = blockElements
+	return nil
+}
+
+// MarshalJSON implements the Marshaller interface for Accessory so that any JSON
+// marshalling is delegated and proper type determination can be made before marshal
+func (a *Accessory) MarshalJSON() ([]byte, error) {
+	bytes, err := json.Marshal(toBlockElement(a))
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes, nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for Accessory, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (a *Accessory) UnmarshalJSON(data []byte) error {
+	var r json.RawMessage
+
+	if string(data) == "{\"accessory\":null}" {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &r)
+	if err != nil {
+		return err
+	}
+
+	s := sumtype{}
+	err = json.Unmarshal(r, &s)
+	if err != nil {
+		return err
+	}
+
+	var blockElementType string
+	if s.TypeVal != "" {
+		blockElementType = s.TypeVal
+	}
+
+	switch blockElementType {
+	case "image":
+		element, err := unmarshalBlockElement(r, &ImageBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.ImageElement = element.(*ImageBlockElement)
+	case "button":
+		element, err := unmarshalBlockElement(r, &ButtonBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.ButtonElement = element.(*ButtonBlockElement)
+	case "overflow":
+		element, err := unmarshalBlockElement(r, &OverflowBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.OverflowElement = element.(*OverflowBlockElement)
+	case "datepicker":
+		element, err := unmarshalBlockElement(r, &DatePickerBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.DatePickerElement = element.(*DatePickerBlockElement)
+	case "timepicker":
+		element, err := unmarshalBlockElement(r, &TimePickerBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.TimePickerElement = element.(*TimePickerBlockElement)
+	case "plain_text_input":
+		element, err := unmarshalBlockElement(r, &PlainTextInputBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.PlainTextInputElement = element.(*PlainTextInputBlockElement)
+	case "radio_buttons":
+		element, err := unmarshalBlockElement(r, &RadioButtonsBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.RadioButtonsElement = element.(*RadioButtonsBlockElement)
+	case "static_select", "external_select", "users_select", "conversations_select", "channels_select":
+		element, err := unmarshalBlockElement(r, &SelectBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.SelectElement = element.(*SelectBlockElement)
+	case "multi_static_select", "multi_external_select", "multi_users_select", "multi_conversations_select", "multi_channels_select":
+		element, err := unmarshalBlockElement(r, &MultiSelectBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.MultiSelectElement = element.(*MultiSelectBlockElement)
+	case "checkboxes":
+		element, err := unmarshalBlockElement(r, &CheckboxGroupsBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.CheckboxGroupsBlockElement = element.(*CheckboxGroupsBlockElement)
+	default:
+		element, err := unmarshalBlockElement(r, &UnknownBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.UnknownElement = element.(*UnknownBlockElement)
+	}
+
+	return nil
+}
+
+func unmarshalBlockElement(r json.RawMessage, element BlockElement) (BlockElement, error) {
+	err := json.Unmarshal(r, element)
+	if err != nil {
+		return nil, err
+	}
+	return element, nil
+}
+
+func toBlockElement(element *Accessory) BlockElement {
+	if element.ImageElement != nil {
+		return element.ImageElement
+	}
+	if element.ButtonElement != nil {
+		return element.ButtonElement
+	}
+	if element.OverflowElement != nil {
+		return element.OverflowElement
+	}
+	if element.DatePickerElement != nil {
+		return element.DatePickerElement
+	}
+	if element.TimePickerElement != nil {
+		return element.TimePickerElement
+	}
+	if element.PlainTextInputElement != nil {
+		return element.PlainTextInputElement
+	}
+	if element.RadioButtonsElement != nil {
+		return element.RadioButtonsElement
+	}
+	if element.CheckboxGroupsBlockElement != nil {
+		return element.CheckboxGroupsBlockElement
+	}
+	if element.SelectElement != nil {
+		return element.SelectElement
+	}
+	if element.MultiSelectElement != nil {
+		return element.MultiSelectElement
+	}
+
+	return nil
+}
+
+// MarshalJSON implements the Marshaller interface for ContextElements so that any JSON
+// marshalling is delegated and proper type determination can be made before marshal
+func (e *ContextElements) MarshalJSON() ([]byte, error) {
+	bytes, err := json.Marshal(e.Elements)
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes, nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for ContextElements, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (e *ContextElements) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+
+	if string(data) == "{\"elements\":null}" {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	for _, r := range raw {
+		s := sumtype{}
+		err := json.Unmarshal(r, &s)
+		if err != nil {
+			return err
+		}
+
+		var contextElementType string
+		if s.TypeVal != "" {
+			contextElementType = s.TypeVal
+		}
+
+		switch contextElementType {
+		case PlainTextType, MarkdownType:
+			elem, err := unmarshalBlockObject(r, &TextBlockObject{})
+			if err != nil {
+				return err
+			}
+
+			e.Elements = append(e.Elements, elem.(*TextBlockObject))
+		case "image":
+			elem, err := unmarshalBlockElement(r, &ImageBlockElement{})
+			if err != nil {
+				return err
+			}
+
+			e.Elements = append(e.Elements, elem.(*ImageBlockElement))
+		default:
+			return errors.New("unsupported context element type")
+		}
+	}
+
+	return nil
+}

backend/vendor/github.com/slack-go/slack/block_divider.go

@@ -0,0 +1,22 @@
+package slack
+
+// DividerBlock for displaying a divider line between blocks (similar to <hr> tag in html)
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#divider
+type DividerBlock struct {
+	Type    MessageBlockType `json:"type"`
+	BlockID string           `json:"block_id,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (s DividerBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewDividerBlock returns a new instance of a divider block
+func NewDividerBlock() *DividerBlock {
+	return &DividerBlock{
+		Type: MBTDivider,
+	}
+
+}

backend/vendor/github.com/slack-go/slack/block_element.go

@@ -0,0 +1,466 @@
+package slack
+
+// https://api.slack.com/reference/messaging/block-elements
+
+const (
+	METCheckboxGroups MessageElementType = "checkboxes"
+	METImage          MessageElementType = "image"
+	METButton         MessageElementType = "button"
+	METOverflow       MessageElementType = "overflow"
+	METDatepicker     MessageElementType = "datepicker"
+	METTimepicker     MessageElementType = "timepicker"
+	METPlainTextInput MessageElementType = "plain_text_input"
+	METRadioButtons   MessageElementType = "radio_buttons"
+
+	MixedElementImage MixedElementType = "mixed_image"
+	MixedElementText  MixedElementType = "mixed_text"
+
+	OptTypeStatic        string = "static_select"
+	OptTypeExternal      string = "external_select"
+	OptTypeUser          string = "users_select"
+	OptTypeConversations string = "conversations_select"
+	OptTypeChannels      string = "channels_select"
+
+	MultiOptTypeStatic        string = "multi_static_select"
+	MultiOptTypeExternal      string = "multi_external_select"
+	MultiOptTypeUser          string = "multi_users_select"
+	MultiOptTypeConversations string = "multi_conversations_select"
+	MultiOptTypeChannels      string = "multi_channels_select"
+)
+
+type MessageElementType string
+type MixedElementType string
+
+// BlockElement defines an interface that all block element types should implement.
+type BlockElement interface {
+	ElementType() MessageElementType
+}
+
+type MixedElement interface {
+	MixedElementType() MixedElementType
+}
+
+type Accessory struct {
+	ImageElement               *ImageBlockElement
+	ButtonElement              *ButtonBlockElement
+	OverflowElement            *OverflowBlockElement
+	DatePickerElement          *DatePickerBlockElement
+	TimePickerElement          *TimePickerBlockElement
+	PlainTextInputElement      *PlainTextInputBlockElement
+	RadioButtonsElement        *RadioButtonsBlockElement
+	SelectElement              *SelectBlockElement
+	MultiSelectElement         *MultiSelectBlockElement
+	CheckboxGroupsBlockElement *CheckboxGroupsBlockElement
+	UnknownElement             *UnknownBlockElement
+}
+
+// NewAccessory returns a new Accessory for a given block element
+func NewAccessory(element BlockElement) *Accessory {
+	switch element.(type) {
+	case *ImageBlockElement:
+		return &Accessory{ImageElement: element.(*ImageBlockElement)}
+	case *ButtonBlockElement:
+		return &Accessory{ButtonElement: element.(*ButtonBlockElement)}
+	case *OverflowBlockElement:
+		return &Accessory{OverflowElement: element.(*OverflowBlockElement)}
+	case *DatePickerBlockElement:
+		return &Accessory{DatePickerElement: element.(*DatePickerBlockElement)}
+	case *TimePickerBlockElement:
+		return &Accessory{TimePickerElement: element.(*TimePickerBlockElement)}
+	case *PlainTextInputBlockElement:
+		return &Accessory{PlainTextInputElement: element.(*PlainTextInputBlockElement)}
+	case *RadioButtonsBlockElement:
+		return &Accessory{RadioButtonsElement: element.(*RadioButtonsBlockElement)}
+	case *SelectBlockElement:
+		return &Accessory{SelectElement: element.(*SelectBlockElement)}
+	case *MultiSelectBlockElement:
+		return &Accessory{MultiSelectElement: element.(*MultiSelectBlockElement)}
+	case *CheckboxGroupsBlockElement:
+		return &Accessory{CheckboxGroupsBlockElement: element.(*CheckboxGroupsBlockElement)}
+	default:
+		return &Accessory{UnknownElement: element.(*UnknownBlockElement)}
+	}
+}
+
+// BlockElements is a convenience struct defined to allow dynamic unmarshalling of
+// the "elements" value in Slack's JSON response, which varies depending on BlockElement type
+type BlockElements struct {
+	ElementSet []BlockElement `json:"elements,omitempty"`
+}
+
+// UnknownBlockElement any block element that this library does not directly support.
+// See the "Rich Elements" section at the following URL:
+// https://api.slack.com/changelog/2019-09-what-they-see-is-what-you-get-and-more-and-less
+// New block element types may be introduced by Slack at any time; this is a catch-all for any such block elements.
+type UnknownBlockElement struct {
+	Type     MessageElementType `json:"type"`
+	Elements BlockElements
+}
+
+// ElementType returns the type of the Element
+func (s UnknownBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// ImageBlockElement An element to insert an image - this element can be used
+// in section and context blocks only. If you want a block with only an image
+// in it, you're looking for the image block.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#image
+type ImageBlockElement struct {
+	Type     MessageElementType `json:"type"`
+	ImageURL string             `json:"image_url"`
+	AltText  string             `json:"alt_text"`
+}
+
+// ElementType returns the type of the Element
+func (s ImageBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+func (s ImageBlockElement) MixedElementType() MixedElementType {
+	return MixedElementImage
+}
+
+// NewImageBlockElement returns a new instance of an image block element
+func NewImageBlockElement(imageURL, altText string) *ImageBlockElement {
+	return &ImageBlockElement{
+		Type:     METImage,
+		ImageURL: imageURL,
+		AltText:  altText,
+	}
+}
+
+// Style is a style of Button element
+// https://api.slack.com/reference/block-kit/block-elements#button__fields
+type Style string
+
+const (
+	StyleDefault Style = ""
+	StylePrimary Style = "primary"
+	StyleDanger  Style = "danger"
+)
+
+// ButtonBlockElement defines an interactive element that inserts a button. The
+// button can be a trigger for anything from opening a simple link to starting
+// a complex workflow.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#button
+type ButtonBlockElement struct {
+	Type     MessageElementType       `json:"type,omitempty"`
+	Text     *TextBlockObject         `json:"text"`
+	ActionID string                   `json:"action_id,omitempty"`
+	URL      string                   `json:"url,omitempty"`
+	Value    string                   `json:"value,omitempty"`
+	Confirm  *ConfirmationBlockObject `json:"confirm,omitempty"`
+	Style    Style                    `json:"style,omitempty"`
+}
+
+// ElementType returns the type of the element
+func (s ButtonBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// WithStyle adds styling to the button object and returns the modified ButtonBlockElement
+func (s *ButtonBlockElement) WithStyle(style Style) *ButtonBlockElement {
+	s.Style = style
+	return s
+}
+
+// NewButtonBlockElement returns an instance of a new button element to be used within a block
+func NewButtonBlockElement(actionID, value string, text *TextBlockObject) *ButtonBlockElement {
+	return &ButtonBlockElement{
+		Type:     METButton,
+		ActionID: actionID,
+		Text:     text,
+		Value:    value,
+	}
+}
+
+// OptionsResponse defines the response used for select block typahead.
+//
+// More Information: https://api.slack.com/reference/block-kit/block-elements#external_multi_select
+type OptionsResponse struct {
+	Options []*OptionBlockObject `json:"options,omitempty"`
+}
+
+// OptionGroupsResponse defines the response used for select block typahead.
+//
+// More Information: https://api.slack.com/reference/block-kit/block-elements#external_multi_select
+type OptionGroupsResponse struct {
+	OptionGroups []*OptionGroupBlockObject `json:"option_groups,omitempty"`
+}
+
+// SelectBlockElement defines the simplest form of select menu, with a static list
+// of options passed in when defining the element.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#select
+type SelectBlockElement struct {
+	Type                         string                    `json:"type,omitempty"`
+	Placeholder                  *TextBlockObject          `json:"placeholder,omitempty"`
+	ActionID                     string                    `json:"action_id,omitempty"`
+	Options                      []*OptionBlockObject      `json:"options,omitempty"`
+	OptionGroups                 []*OptionGroupBlockObject `json:"option_groups,omitempty"`
+	InitialOption                *OptionBlockObject        `json:"initial_option,omitempty"`
+	InitialUser                  string                    `json:"initial_user,omitempty"`
+	InitialConversation          string                    `json:"initial_conversation,omitempty"`
+	InitialChannel               string                    `json:"initial_channel,omitempty"`
+	DefaultToCurrentConversation bool                      `json:"default_to_current_conversation,omitempty"`
+	ResponseURLEnabled           bool                      `json:"response_url_enabled,omitempty"`
+	Filter                       *SelectBlockElementFilter `json:"filter,omitempty"`
+	MinQueryLength               *int                      `json:"min_query_length,omitempty"`
+	Confirm                      *ConfirmationBlockObject  `json:"confirm,omitempty"`
+}
+
+// SelectBlockElementFilter allows to filter select element conversation options by type.
+//
+// More Information: https://api.slack.com/reference/block-kit/composition-objects#filter_conversations
+type SelectBlockElementFilter struct {
+	Include                       []string `json:"include,omitempty"`
+	ExcludeExternalSharedChannels bool     `json:"exclude_external_shared_channels,omitempty"`
+	ExcludeBotUsers               bool     `json:"exclude_bot_users,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s SelectBlockElement) ElementType() MessageElementType {
+	return MessageElementType(s.Type)
+}
+
+// NewOptionsSelectBlockElement returns a new instance of SelectBlockElement for use with
+// the Options object only.
+func NewOptionsSelectBlockElement(optType string, placeholder *TextBlockObject, actionID string, options ...*OptionBlockObject) *SelectBlockElement {
+	return &SelectBlockElement{
+		Type:        optType,
+		Placeholder: placeholder,
+		ActionID:    actionID,
+		Options:     options,
+	}
+}
+
+// NewOptionsGroupSelectBlockElement returns a new instance of SelectBlockElement for use with
+// the Options object only.
+func NewOptionsGroupSelectBlockElement(
+	optType string,
+	placeholder *TextBlockObject,
+	actionID string,
+	optGroups ...*OptionGroupBlockObject,
+) *SelectBlockElement {
+	return &SelectBlockElement{
+		Type:         optType,
+		Placeholder:  placeholder,
+		ActionID:     actionID,
+		OptionGroups: optGroups,
+	}
+}
+
+// MultiSelectBlockElement defines a multiselect menu, with a static list
+// of options passed in when defining the element.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#multi_select
+type MultiSelectBlockElement struct {
+	Type                 string                    `json:"type,omitempty"`
+	Placeholder          *TextBlockObject          `json:"placeholder,omitempty"`
+	ActionID             string                    `json:"action_id,omitempty"`
+	Options              []*OptionBlockObject      `json:"options,omitempty"`
+	OptionGroups         []*OptionGroupBlockObject `json:"option_groups,omitempty"`
+	InitialOptions       []*OptionBlockObject      `json:"initial_options,omitempty"`
+	InitialUsers         []string                  `json:"initial_users,omitempty"`
+	InitialConversations []string                  `json:"initial_conversations,omitempty"`
+	InitialChannels      []string                  `json:"initial_channels,omitempty"`
+	MinQueryLength       *int                      `json:"min_query_length,omitempty"`
+	MaxSelectedItems     *int                      `json:"max_selected_items,omitempty"`
+	Confirm              *ConfirmationBlockObject  `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s MultiSelectBlockElement) ElementType() MessageElementType {
+	return MessageElementType(s.Type)
+}
+
+// NewOptionsMultiSelectBlockElement returns a new instance of SelectBlockElement for use with
+// the Options object only.
+func NewOptionsMultiSelectBlockElement(optType string, placeholder *TextBlockObject, actionID string, options ...*OptionBlockObject) *MultiSelectBlockElement {
+	return &MultiSelectBlockElement{
+		Type:        optType,
+		Placeholder: placeholder,
+		ActionID:    actionID,
+		Options:     options,
+	}
+}
+
+// NewOptionsGroupMultiSelectBlockElement returns a new instance of MultiSelectBlockElement for use with
+// the Options object only.
+func NewOptionsGroupMultiSelectBlockElement(
+	optType string,
+	placeholder *TextBlockObject,
+	actionID string,
+	optGroups ...*OptionGroupBlockObject,
+) *MultiSelectBlockElement {
+	return &MultiSelectBlockElement{
+		Type:         optType,
+		Placeholder:  placeholder,
+		ActionID:     actionID,
+		OptionGroups: optGroups,
+	}
+}
+
+// OverflowBlockElement defines the fields needed to use an overflow element.
+// And Overflow Element is like a cross between a button and a select menu -
+// when a user clicks on this overflow button, they will be presented with a
+// list of options to choose from.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#overflow
+type OverflowBlockElement struct {
+	Type     MessageElementType       `json:"type"`
+	ActionID string                   `json:"action_id,omitempty"`
+	Options  []*OptionBlockObject     `json:"options"`
+	Confirm  *ConfirmationBlockObject `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s OverflowBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// NewOverflowBlockElement returns an instance of a new Overflow Block Element
+func NewOverflowBlockElement(actionID string, options ...*OptionBlockObject) *OverflowBlockElement {
+	return &OverflowBlockElement{
+		Type:     METOverflow,
+		ActionID: actionID,
+		Options:  options,
+	}
+}
+
+// DatePickerBlockElement defines an element which lets users easily select a
+// date from a calendar style UI. Date picker elements can be used inside of
+// section and actions blocks.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#datepicker
+type DatePickerBlockElement struct {
+	Type        MessageElementType       `json:"type"`
+	ActionID    string                   `json:"action_id,omitempty"`
+	Placeholder *TextBlockObject         `json:"placeholder,omitempty"`
+	InitialDate string                   `json:"initial_date,omitempty"`
+	Confirm     *ConfirmationBlockObject `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s DatePickerBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// NewDatePickerBlockElement returns an instance of a date picker element
+func NewDatePickerBlockElement(actionID string) *DatePickerBlockElement {
+	return &DatePickerBlockElement{
+		Type:     METDatepicker,
+		ActionID: actionID,
+	}
+}
+
+// TimePickerBlockElement defines an element which lets users easily select a
+// time from nice UI. Time picker elements can be used inside of
+// section and actions blocks.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#timepicker
+type TimePickerBlockElement struct {
+	Type        MessageElementType       `json:"type"`
+	ActionID    string                   `json:"action_id,omitempty"`
+	Placeholder *TextBlockObject         `json:"placeholder,omitempty"`
+	InitialTime string                   `json:"initial_time,omitempty"`
+	Confirm     *ConfirmationBlockObject `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s TimePickerBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// NewTimePickerBlockElement returns an instance of a date picker element
+func NewTimePickerBlockElement(actionID string) *TimePickerBlockElement {
+	return &TimePickerBlockElement{
+		Type:     METTimepicker,
+		ActionID: actionID,
+	}
+}
+
+// PlainTextInputBlockElement creates a field where a user can enter freeform
+// data.
+// Plain-text input elements are currently only available in modals.
+//
+// More Information: https://api.slack.com/reference/block-kit/block-elements#input
+type PlainTextInputBlockElement struct {
+	Type         MessageElementType `json:"type"`
+	ActionID     string             `json:"action_id,omitempty"`
+	Placeholder  *TextBlockObject   `json:"placeholder,omitempty"`
+	InitialValue string             `json:"initial_value,omitempty"`
+	Multiline    bool               `json:"multiline,omitempty"`
+	MinLength    int                `json:"min_length,omitempty"`
+	MaxLength    int                `json:"max_length,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s PlainTextInputBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// NewPlainTextInputBlockElement returns an instance of a plain-text input
+// element
+func NewPlainTextInputBlockElement(placeholder *TextBlockObject, actionID string) *PlainTextInputBlockElement {
+	return &PlainTextInputBlockElement{
+		Type:        METPlainTextInput,
+		ActionID:    actionID,
+		Placeholder: placeholder,
+	}
+}
+
+// CheckboxGroupsBlockElement defines an element which allows users to choose
+// one or more items from a list of possible options.
+//
+// More Information: https://api.slack.com/reference/block-kit/block-elements#checkboxes
+type CheckboxGroupsBlockElement struct {
+	Type           MessageElementType       `json:"type"`
+	ActionID       string                   `json:"action_id,omitempty"`
+	Options        []*OptionBlockObject     `json:"options"`
+	InitialOptions []*OptionBlockObject     `json:"initial_options,omitempty"`
+	Confirm        *ConfirmationBlockObject `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (c CheckboxGroupsBlockElement) ElementType() MessageElementType {
+	return c.Type
+}
+
+// NewCheckboxGroupsBlockElement returns an instance of a checkbox-group block element
+func NewCheckboxGroupsBlockElement(actionID string, options ...*OptionBlockObject) *CheckboxGroupsBlockElement {
+	return &CheckboxGroupsBlockElement{
+		Type:     METCheckboxGroups,
+		ActionID: actionID,
+		Options:  options,
+	}
+}
+
+// RadioButtonsBlockElement defines an element which lets users choose one item
+// from a list of possible options.
+//
+// More Information: https://api.slack.com/reference/block-kit/block-elements#radio
+type RadioButtonsBlockElement struct {
+	Type          MessageElementType       `json:"type"`
+	ActionID      string                   `json:"action_id,omitempty"`
+	Options       []*OptionBlockObject     `json:"options"`
+	InitialOption *OptionBlockObject       `json:"initial_option,omitempty"`
+	Confirm       *ConfirmationBlockObject `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s RadioButtonsBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// NewRadioButtonsBlockElement returns an instance of a radio buttons element.
+func NewRadioButtonsBlockElement(actionID string, options ...*OptionBlockObject) *RadioButtonsBlockElement {
+	return &RadioButtonsBlockElement{
+		Type:     METRadioButtons,
+		ActionID: actionID,
+		Options:  options,
+	}
+}

backend/vendor/github.com/slack-go/slack/block_file.go

@@ -0,0 +1,26 @@
+package slack
+
+// FileBlock defines data that is used to display a remote file.
+//
+// More Information: https://api.slack.com/reference/block-kit/blocks#file
+type FileBlock struct {
+	Type       MessageBlockType `json:"type"`
+	BlockID    string           `json:"block_id,omitempty"`
+	ExternalID string           `json:"external_id"`
+	Source     string           `json:"source"`
+}
+
+// BlockType returns the type of the block
+func (s FileBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewFileBlock returns a new instance of a file block
+func NewFileBlock(blockID string, externalID string, source string) *FileBlock {
+	return &FileBlock{
+		Type:       MBTFile,
+		BlockID:    blockID,
+		ExternalID: externalID,
+		Source:     source,
+	}
+}

backend/vendor/github.com/slack-go/slack/block_header.go

@@ -0,0 +1,38 @@
+package slack
+
+// HeaderBlock defines a new block of type header
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#header
+type HeaderBlock struct {
+	Type    MessageBlockType `json:"type"`
+	Text    *TextBlockObject `json:"text,omitempty"`
+	BlockID string           `json:"block_id,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (s HeaderBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// HeaderBlockOption allows configuration of options for a new header block
+type HeaderBlockOption func(*HeaderBlock)
+
+func HeaderBlockOptionBlockID(blockID string) HeaderBlockOption {
+	return func(block *HeaderBlock) {
+		block.BlockID = blockID
+	}
+}
+
+// NewHeaderBlock returns a new instance of a header block to be rendered
+func NewHeaderBlock(textObj *TextBlockObject, options ...HeaderBlockOption) *HeaderBlock {
+	block := HeaderBlock{
+		Type: MBTHeader,
+		Text: textObj,
+	}
+
+	for _, option := range options {
+		option(&block)
+	}
+
+	return &block
+}

backend/vendor/github.com/slack-go/slack/block_image.go

@@ -0,0 +1,28 @@
+package slack
+
+// ImageBlock defines data required to display an image as a block element
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#image
+type ImageBlock struct {
+	Type     MessageBlockType `json:"type"`
+	ImageURL string           `json:"image_url"`
+	AltText  string           `json:"alt_text"`
+	BlockID  string           `json:"block_id,omitempty"`
+	Title    *TextBlockObject `json:"title,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (s ImageBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewImageBlock returns an instance of a new Image Block type
+func NewImageBlock(imageURL, altText, blockID string, title *TextBlockObject) *ImageBlock {
+	return &ImageBlock{
+		Type:     MBTImage,
+		ImageURL: imageURL,
+		AltText:  altText,
+		BlockID:  blockID,
+		Title:    title,
+	}
+}

backend/vendor/github.com/slack-go/slack/block_input.go

@@ -0,0 +1,29 @@
+package slack
+
+// InputBlock defines data that is used to display user input fields.
+//
+// More Information: https://api.slack.com/reference/block-kit/blocks#input
+type InputBlock struct {
+	Type           MessageBlockType `json:"type"`
+	BlockID        string           `json:"block_id,omitempty"`
+	Label          *TextBlockObject `json:"label"`
+	Element        BlockElement     `json:"element"`
+	Hint           *TextBlockObject `json:"hint,omitempty"`
+	Optional       bool             `json:"optional,omitempty"`
+	DispatchAction bool             `json:"dispatch_action,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (s InputBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewInputBlock returns a new instance of an input block
+func NewInputBlock(blockID string, label *TextBlockObject, element BlockElement) *InputBlock {
+	return &InputBlock{
+		Type:    MBTInput,
+		BlockID: blockID,
+		Label:   label,
+		Element: element,
+	}
+}

backend/vendor/github.com/slack-go/slack/block_object.go

@@ -0,0 +1,247 @@
+package slack
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+// Block Objects are also known as Composition Objects
+//
+// For more information: https://api.slack.com/reference/messaging/composition-objects
+
+// BlockObject defines an interface that all block object types should
+// implement.
+// @TODO: Is this interface needed?
+
+// blockObject object types
+const (
+	MarkdownType  = "mrkdwn"
+	PlainTextType = "plain_text"
+	// The following objects don't actually have types and their corresponding
+	// const values are just for internal use
+	motConfirmation = "confirm"
+	motOption       = "option"
+	motOptionGroup  = "option_group"
+)
+
+type MessageObjectType string
+
+type blockObject interface {
+	validateType() MessageObjectType
+}
+
+type BlockObjects struct {
+	TextObjects         []*TextBlockObject
+	ConfirmationObjects []*ConfirmationBlockObject
+	OptionObjects       []*OptionBlockObject
+	OptionGroupObjects  []*OptionGroupBlockObject
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for BlockObjects, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (b *BlockObjects) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	for _, r := range raw {
+		var obj map[string]interface{}
+		err := json.Unmarshal(r, &obj)
+		if err != nil {
+			return err
+		}
+
+		blockObjectType := getBlockObjectType(obj)
+
+		switch blockObjectType {
+		case PlainTextType, MarkdownType:
+			object, err := unmarshalBlockObject(r, &TextBlockObject{})
+			if err != nil {
+				return err
+			}
+			b.TextObjects = append(b.TextObjects, object.(*TextBlockObject))
+		case motConfirmation:
+			object, err := unmarshalBlockObject(r, &ConfirmationBlockObject{})
+			if err != nil {
+				return err
+			}
+			b.ConfirmationObjects = append(b.ConfirmationObjects, object.(*ConfirmationBlockObject))
+		case motOption:
+			object, err := unmarshalBlockObject(r, &OptionBlockObject{})
+			if err != nil {
+				return err
+			}
+			b.OptionObjects = append(b.OptionObjects, object.(*OptionBlockObject))
+		case motOptionGroup:
+			object, err := unmarshalBlockObject(r, &OptionGroupBlockObject{})
+			if err != nil {
+				return err
+			}
+			b.OptionGroupObjects = append(b.OptionGroupObjects, object.(*OptionGroupBlockObject))
+
+		}
+	}
+
+	return nil
+}
+
+// Ideally would have a better way to identify the block objects for
+// type casting at time of unmarshalling, should be adapted if possible
+// to accomplish in a more reliable manner.
+func getBlockObjectType(obj map[string]interface{}) string {
+	if t, ok := obj["type"].(string); ok {
+		return t
+	}
+	if _, ok := obj["confirm"].(string); ok {
+		return "confirm"
+	}
+	if _, ok := obj["options"].(string); ok {
+		return "option_group"
+	}
+	if _, ok := obj["text"].(string); ok {
+		if _, ok := obj["value"].(string); ok {
+			return "option"
+		}
+	}
+	return ""
+}
+
+func unmarshalBlockObject(r json.RawMessage, object blockObject) (blockObject, error) {
+	err := json.Unmarshal(r, object)
+	if err != nil {
+		return nil, err
+	}
+	return object, nil
+}
+
+// TextBlockObject defines a text element object to be used with blocks
+//
+// More Information: https://api.slack.com/reference/messaging/composition-objects#text
+type TextBlockObject struct {
+	Type     string `json:"type"`
+	Text     string `json:"text"`
+	Emoji    bool   `json:"emoji,omitempty"`
+	Verbatim bool   `json:"verbatim,omitempty"`
+}
+
+// validateType enforces block objects for element and block parameters
+func (s TextBlockObject) validateType() MessageObjectType {
+	return MessageObjectType(s.Type)
+}
+
+// validateType enforces block objects for element and block parameters
+func (s TextBlockObject) MixedElementType() MixedElementType {
+	return MixedElementText
+}
+
+// Validate checks if TextBlockObject has valid values
+func (s TextBlockObject) Validate() error {
+	if s.Type != "plain_text" && s.Type != "mrkdwn" {
+		return errors.New("type must be either of plain_text or mrkdwn")
+	}
+
+	// https://github.com/slack-go/slack/issues/881
+	if s.Type == "mrkdwn" && s.Emoji {
+		return errors.New("emoji cannot be true in mrkdown")
+	}
+
+	return nil
+}
+
+// NewTextBlockObject returns an instance of a new Text Block Object
+func NewTextBlockObject(elementType, text string, emoji, verbatim bool) *TextBlockObject {
+	return &TextBlockObject{
+		Type:     elementType,
+		Text:     text,
+		Emoji:    emoji,
+		Verbatim: verbatim,
+	}
+}
+
+// BlockType returns the type of the block
+func (t TextBlockObject) BlockType() MessageBlockType {
+	if t.Type == "mrkdwn" {
+		return MarkdownType
+	}
+	return PlainTextType
+}
+
+// ConfirmationBlockObject defines a dialog that provides a confirmation step to
+// any interactive element. This dialog will ask the user to confirm their action by
+// offering a confirm and deny buttons.
+//
+// More Information: https://api.slack.com/reference/messaging/composition-objects#confirm
+type ConfirmationBlockObject struct {
+	Title   *TextBlockObject `json:"title"`
+	Text    *TextBlockObject `json:"text"`
+	Confirm *TextBlockObject `json:"confirm"`
+	Deny    *TextBlockObject `json:"deny"`
+	Style   Style            `json:"style,omitempty"`
+}
+
+// validateType enforces block objects for element and block parameters
+func (s ConfirmationBlockObject) validateType() MessageObjectType {
+	return motConfirmation
+}
+
+// WithStyle add styling to confirmation object
+func (s *ConfirmationBlockObject) WithStyle(style Style) {
+	s.Style = style
+}
+
+// NewConfirmationBlockObject returns an instance of a new Confirmation Block Object
+func NewConfirmationBlockObject(title, text, confirm, deny *TextBlockObject) *ConfirmationBlockObject {
+	return &ConfirmationBlockObject{
+		Title:   title,
+		Text:    text,
+		Confirm: confirm,
+		Deny:    deny,
+	}
+}
+
+// OptionBlockObject represents a single selectable item in a select menu
+//
+// More Information: https://api.slack.com/reference/messaging/composition-objects#option
+type OptionBlockObject struct {
+	Text        *TextBlockObject `json:"text"`
+	Value       string           `json:"value"`
+	Description *TextBlockObject `json:"description,omitempty"`
+	URL         string           `json:"url,omitempty"`
+}
+
+// NewOptionBlockObject returns an instance of a new Option Block Element
+func NewOptionBlockObject(value string, text, description *TextBlockObject) *OptionBlockObject {
+	return &OptionBlockObject{
+		Text:        text,
+		Value:       value,
+		Description: description,
+	}
+}
+
+// validateType enforces block objects for element and block parameters
+func (s OptionBlockObject) validateType() MessageObjectType {
+	return motOption
+}
+
+// OptionGroupBlockObject Provides a way to group options in a select menu.
+//
+// More Information: https://api.slack.com/reference/messaging/composition-objects#option-group
+type OptionGroupBlockObject struct {
+	Label   *TextBlockObject     `json:"label,omitempty"`
+	Options []*OptionBlockObject `json:"options"`
+}
+
+// validateType enforces block objects for element and block parameters
+func (s OptionGroupBlockObject) validateType() MessageObjectType {
+	return motOptionGroup
+}
+
+// NewOptionGroupBlockElement returns an instance of a new option group block element
+func NewOptionGroupBlockElement(label *TextBlockObject, options ...*OptionBlockObject) *OptionGroupBlockObject {
+	return &OptionGroupBlockObject{
+		Label:   label,
+		Options: options,
+	}
+}

backend/vendor/github.com/slack-go/slack/block_section.go

@@ -0,0 +1,42 @@
+package slack
+
+// SectionBlock defines a new block of type section
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#section
+type SectionBlock struct {
+	Type      MessageBlockType   `json:"type"`
+	Text      *TextBlockObject   `json:"text,omitempty"`
+	BlockID   string             `json:"block_id,omitempty"`
+	Fields    []*TextBlockObject `json:"fields,omitempty"`
+	Accessory *Accessory         `json:"accessory,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (s SectionBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// SectionBlockOption allows configuration of options for a new section block
+type SectionBlockOption func(*SectionBlock)
+
+func SectionBlockOptionBlockID(blockID string) SectionBlockOption {
+	return func(block *SectionBlock) {
+		block.BlockID = blockID
+	}
+}
+
+// NewSectionBlock returns a new instance of a section block to be rendered
+func NewSectionBlock(textObj *TextBlockObject, fields []*TextBlockObject, accessory *Accessory, options ...SectionBlockOption) *SectionBlock {
+	block := SectionBlock{
+		Type:      MBTSection,
+		Text:      textObj,
+		Fields:    fields,
+		Accessory: accessory,
+	}
+
+	for _, option := range options {
+		option(&block)
+	}
+
+	return &block
+}

backend/vendor/github.com/slack-go/slack/block_unknown.go

@@ -0,0 +1,13 @@
+package slack
+
+// UnknownBlock represents a block type that is not yet known. This block type exists to prevent Slack from introducing
+// new and unknown block types that break this library.
+type UnknownBlock struct {
+	Type    MessageBlockType `json:"type"`
+	BlockID string           `json:"block_id,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (b UnknownBlock) BlockType() MessageBlockType {
+	return b.Type
+}

backend/vendor/github.com/slack-go/slack/bots.go

@@ -0,0 +1,58 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+// Bot contains information about a bot
+type Bot struct {
+	ID      string   `json:"id"`
+	Name    string   `json:"name"`
+	Deleted bool     `json:"deleted"`
+	UserID  string   `json:"user_id"`
+	AppID   string   `json:"app_id"`
+	Updated JSONTime `json:"updated"`
+	Icons   Icons    `json:"icons"`
+}
+
+type botResponseFull struct {
+	Bot `json:"bot,omitempty"` // GetBotInfo
+	SlackResponse
+}
+
+func (api *Client) botRequest(ctx context.Context, path string, values url.Values) (*botResponseFull, error) {
+	response := &botResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}
+
+// GetBotInfo will retrieve the complete bot information
+func (api *Client) GetBotInfo(bot string) (*Bot, error) {
+	return api.GetBotInfoContext(context.Background(), bot)
+}
+
+// GetBotInfoContext will retrieve the complete bot information using a custom context
+func (api *Client) GetBotInfoContext(ctx context.Context, bot string) (*Bot, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	if bot != "" {
+		values.Add("bot", bot)
+	}
+
+	response, err := api.botRequest(ctx, "bots.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Bot, nil
+}

backend/vendor/github.com/slack-go/slack/channels.go

@@ -0,0 +1,714 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+type channelResponseFull struct {
+	Channel      Channel   `json:"channel"`
+	Channels     []Channel `json:"channels"`
+	Purpose      string    `json:"purpose"`
+	Topic        string    `json:"topic"`
+	NotInChannel bool      `json:"not_in_channel"`
+	History
+	SlackResponse
+	Metadata ResponseMetadata `json:"response_metadata"`
+}
+
+// Channel contains information about the channel
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+type Channel struct {
+	GroupConversation
+	IsChannel bool   `json:"is_channel"`
+	IsGeneral bool   `json:"is_general"`
+	IsMember  bool   `json:"is_member"`
+	Locale    string `json:"locale"`
+}
+
+func (api *Client) channelRequest(ctx context.Context, path string, values url.Values) (*channelResponseFull, error) {
+	response := &channelResponseFull{}
+	err := postForm(ctx, api.httpclient, api.endpoint+path, values, response, api)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// GetChannelsOption option provided when getting channels.
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+type GetChannelsOption func(*ChannelPagination) error
+
+// GetChannelsOptionExcludeMembers excludes the members collection from each channel.
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func GetChannelsOptionExcludeMembers() GetChannelsOption {
+	return func(p *ChannelPagination) error {
+		p.excludeMembers = true
+		return nil
+	}
+}
+
+// GetChannelsOptionExcludeArchived excludes archived channels from results.
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func GetChannelsOptionExcludeArchived() GetChannelsOption {
+	return func(p *ChannelPagination) error {
+		p.excludeArchived = true
+		return nil
+	}
+}
+
+// ArchiveChannel archives the given channel
+// see https://api.slack.com/methods/channels.archive
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) ArchiveChannel(channelID string) error {
+	return api.ArchiveChannelContext(context.Background(), channelID)
+}
+
+// ArchiveChannelContext archives the given channel with a custom context
+// see https://api.slack.com/methods/channels.archive
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) ArchiveChannelContext(ctx context.Context, channelID string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	_, err = api.channelRequest(ctx, "channels.archive", values)
+	return err
+}
+
+// UnarchiveChannel unarchives the given channel
+// see https://api.slack.com/methods/channels.unarchive
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) UnarchiveChannel(channelID string) error {
+	return api.UnarchiveChannelContext(context.Background(), channelID)
+}
+
+// UnarchiveChannelContext unarchives the given channel with a custom context
+// see https://api.slack.com/methods/channels.unarchive
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) UnarchiveChannelContext(ctx context.Context, channelID string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	_, err = api.channelRequest(ctx, "channels.unarchive", values)
+	return err
+}
+
+// CreateChannel creates a channel with the given name and returns a *Channel
+// see https://api.slack.com/methods/channels.create
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) CreateChannel(channelName string) (*Channel, error) {
+	return api.CreateChannelContext(context.Background(), channelName)
+}
+
+// CreateChannelContext creates a channel with the given name and returns a *Channel with a custom context
+// see https://api.slack.com/methods/channels.create
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) CreateChannelContext(ctx context.Context, channelName string) (*Channel, error) {
+	values := url.Values{
+		"token": {api.token},
+		"name":  {channelName},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.create", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// GetChannelHistory retrieves the channel history
+// see https://api.slack.com/methods/channels.history
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannelHistory(channelID string, params HistoryParameters) (*History, error) {
+	return api.GetChannelHistoryContext(context.Background(), channelID, params)
+}
+
+// GetChannelHistoryContext retrieves the channel history with a custom context
+// see https://api.slack.com/methods/channels.history
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannelHistoryContext(ctx context.Context, channelID string, params HistoryParameters) (*History, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+	if params.Latest != DEFAULT_HISTORY_LATEST {
+		values.Add("latest", params.Latest)
+	}
+	if params.Oldest != DEFAULT_HISTORY_OLDEST {
+		values.Add("oldest", params.Oldest)
+	}
+	if params.Count != DEFAULT_HISTORY_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Inclusive != DEFAULT_HISTORY_INCLUSIVE {
+		if params.Inclusive {
+			values.Add("inclusive", "1")
+		} else {
+			values.Add("inclusive", "0")
+		}
+	}
+
+	if params.Unreads != DEFAULT_HISTORY_UNREADS {
+		if params.Unreads {
+			values.Add("unreads", "1")
+		} else {
+			values.Add("unreads", "0")
+		}
+	}
+
+	response, err := api.channelRequest(ctx, "channels.history", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.History, nil
+}
+
+// GetChannelInfo retrieves the given channel
+// see https://api.slack.com/methods/channels.info
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannelInfo(channelID string) (*Channel, error) {
+	return api.GetChannelInfoContext(context.Background(), channelID)
+}
+
+// GetChannelInfoContext retrieves the given channel with a custom context
+// see https://api.slack.com/methods/channels.info
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannelInfoContext(ctx context.Context, channelID string) (*Channel, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"channel":        {channelID},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// InviteUserToChannel invites a user to a given channel and returns a *Channel
+// see https://api.slack.com/methods/channels.invite
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) InviteUserToChannel(channelID, user string) (*Channel, error) {
+	return api.InviteUserToChannelContext(context.Background(), channelID, user)
+}
+
+// InviteUserToChannelContext invites a user to a given channel and returns a *Channel with a custom context
+// see https://api.slack.com/methods/channels.invite
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) InviteUserToChannelContext(ctx context.Context, channelID, user string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"user":    {user},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.invite", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// JoinChannel joins the currently authenticated user to a channel
+// see https://api.slack.com/methods/channels.join
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) JoinChannel(channelName string) (*Channel, error) {
+	return api.JoinChannelContext(context.Background(), channelName)
+}
+
+// JoinChannelContext joins the currently authenticated user to a channel with a custom context
+// see https://api.slack.com/methods/channels.join
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) JoinChannelContext(ctx context.Context, channelName string) (*Channel, error) {
+	values := url.Values{
+		"token": {api.token},
+		"name":  {channelName},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.join", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// LeaveChannel makes the authenticated user leave the given channel
+// see https://api.slack.com/methods/channels.leave
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) LeaveChannel(channelID string) (bool, error) {
+	return api.LeaveChannelContext(context.Background(), channelID)
+}
+
+// LeaveChannelContext makes the authenticated user leave the given channel with a custom context
+// see https://api.slack.com/methods/channels.leave
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) LeaveChannelContext(ctx context.Context, channelID string) (bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.leave", values)
+	if err != nil {
+		return false, err
+	}
+
+	return response.NotInChannel, nil
+}
+
+// KickUserFromChannel kicks a user from a given channel
+// see https://api.slack.com/methods/channels.kick
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) KickUserFromChannel(channelID, user string) error {
+	return api.KickUserFromChannelContext(context.Background(), channelID, user)
+}
+
+// KickUserFromChannelContext kicks a user from a given channel with a custom context
+// see https://api.slack.com/methods/channels.kick
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) KickUserFromChannelContext(ctx context.Context, channelID, user string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"user":    {user},
+	}
+
+	_, err = api.channelRequest(ctx, "channels.kick", values)
+	return err
+}
+
+func newChannelPagination(c *Client, options ...GetChannelsOption) (cp ChannelPagination) {
+	cp = ChannelPagination{
+		c:     c,
+		limit: 200, // per slack api documentation.
+	}
+
+	for _, opt := range options {
+		opt(&cp)
+	}
+
+	return cp
+}
+
+// ChannelPagination allows for paginating over the channels
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+type ChannelPagination struct {
+	Channels        []Channel
+	limit           int
+	excludeArchived bool
+	excludeMembers  bool
+	previousResp    *ResponseMetadata
+	c               *Client
+}
+
+// Done checks if the pagination has completed
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (ChannelPagination) Done(err error) bool {
+	return err == errPaginationComplete
+}
+
+// Failure checks if pagination failed.
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (t ChannelPagination) Failure(err error) error {
+	if t.Done(err) {
+		return nil
+	}
+
+	return err
+}
+
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (t ChannelPagination) Next(ctx context.Context) (_ ChannelPagination, err error) {
+	var (
+		resp *channelResponseFull
+	)
+
+	if t.c == nil || (t.previousResp != nil && t.previousResp.Cursor == "") {
+		return t, errPaginationComplete
+	}
+
+	t.previousResp = t.previousResp.initialize()
+
+	values := url.Values{
+		"limit":            {strconv.Itoa(t.limit)},
+		"exclude_archived": {strconv.FormatBool(t.excludeArchived)},
+		"exclude_members":  {strconv.FormatBool(t.excludeMembers)},
+		"token":            {t.c.token},
+		"cursor":           {t.previousResp.Cursor},
+	}
+
+	if resp, err = t.c.channelRequest(ctx, "channels.list", values); err != nil {
+		return t, err
+	}
+
+	t.c.Debugf("GetChannelsContext: got %d channels; metadata %v", len(resp.Channels), resp.Metadata)
+	t.Channels = resp.Channels
+	t.previousResp = &resp.Metadata
+
+	return t, nil
+}
+
+// GetChannelsPaginated fetches channels in a paginated fashion, see GetChannelsContext for usage.
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannelsPaginated(options ...GetChannelsOption) ChannelPagination {
+	return newChannelPagination(api, options...)
+}
+
+// GetChannels retrieves all the channels
+// see https://api.slack.com/methods/channels.list
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannels(excludeArchived bool, options ...GetChannelsOption) ([]Channel, error) {
+	return api.GetChannelsContext(context.Background(), excludeArchived, options...)
+}
+
+// GetChannelsContext retrieves all the channels with a custom context
+// see https://api.slack.com/methods/channels.list
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannelsContext(ctx context.Context, excludeArchived bool, options ...GetChannelsOption) (results []Channel, err error) {
+	if excludeArchived {
+		options = append(options, GetChannelsOptionExcludeArchived())
+	}
+
+	p := api.GetChannelsPaginated(options...)
+	for err == nil {
+		p, err = p.Next(ctx)
+		if err == nil {
+			results = append(results, p.Channels...)
+		} else if rateLimitedError, ok := err.(*RateLimitedError); ok {
+			select {
+			case <-ctx.Done():
+				err = ctx.Err()
+			case <-time.After(rateLimitedError.RetryAfter):
+				err = nil
+			}
+		}
+	}
+
+	return results, p.Failure(err)
+}
+
+// SetChannelReadMark sets the read mark of a given channel to a specific point
+// Clients should try to avoid making this call too often. When needing to mark a read position, a client should set a
+// timer before making the call. In this way, any further updates needed during the timeout will not generate extra calls
+// (just one per channel). This is useful for when reading scroll-back history, or following a busy live channel. A
+// timeout of 5 seconds is a good starting point. Be sure to flush these calls on shutdown/logout.
+// see https://api.slack.com/methods/channels.mark
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetChannelReadMark(channelID, ts string) error {
+	return api.SetChannelReadMarkContext(context.Background(), channelID, ts)
+}
+
+// SetChannelReadMarkContext sets the read mark of a given channel to a specific point with a custom context
+// For more details see SetChannelReadMark documentation
+// see https://api.slack.com/methods/channels.mark
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetChannelReadMarkContext(ctx context.Context, channelID, ts string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"ts":      {ts},
+	}
+
+	_, err = api.channelRequest(ctx, "channels.mark", values)
+	return err
+}
+
+// RenameChannel renames a given channel
+// see https://api.slack.com/methods/channels.rename
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) RenameChannel(channelID, name string) (*Channel, error) {
+	return api.RenameChannelContext(context.Background(), channelID, name)
+}
+
+// RenameChannelContext renames a given channel with a custom context
+// see https://api.slack.com/methods/channels.rename
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) RenameChannelContext(ctx context.Context, channelID, name string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"name":    {name},
+	}
+
+	// XXX: the created entry in this call returns a string instead of a number
+	// so I may have to do some workaround to solve it.
+	response, err := api.channelRequest(ctx, "channels.rename", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// SetChannelPurpose sets the channel purpose and returns the purpose that was successfully set
+// see https://api.slack.com/methods/channels.setPurpose
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetChannelPurpose(channelID, purpose string) (string, error) {
+	return api.SetChannelPurposeContext(context.Background(), channelID, purpose)
+}
+
+// SetChannelPurposeContext sets the channel purpose and returns the purpose that was successfully set with a custom context
+// see https://api.slack.com/methods/channels.setPurpose
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetChannelPurposeContext(ctx context.Context, channelID, purpose string) (string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"purpose": {purpose},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.setPurpose", values)
+	if err != nil {
+		return "", err
+	}
+	return response.Purpose, nil
+}
+
+// SetChannelTopic sets the channel topic and returns the topic that was successfully set
+// see https://api.slack.com/methods/channels.setTopic
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetChannelTopic(channelID, topic string) (string, error) {
+	return api.SetChannelTopicContext(context.Background(), channelID, topic)
+}
+
+// SetChannelTopicContext sets the channel topic and returns the topic that was successfully set with a custom context
+// see https://api.slack.com/methods/channels.setTopic
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetChannelTopicContext(ctx context.Context, channelID, topic string) (string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"topic":   {topic},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.setTopic", values)
+	if err != nil {
+		return "", err
+	}
+	return response.Topic, nil
+}
+
+// GetChannelReplies gets an entire thread (a message plus all the messages in reply to it).
+// see https://api.slack.com/methods/channels.replies
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannelReplies(channelID, thread_ts string) ([]Message, error) {
+	return api.GetChannelRepliesContext(context.Background(), channelID, thread_ts)
+}
+
+// GetChannelRepliesContext gets an entire thread (a message plus all the messages in reply to it) with a custom context
+// see https://api.slack.com/methods/channels.replies
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetChannelRepliesContext(ctx context.Context, channelID, thread_ts string) ([]Message, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"channel":   {channelID},
+		"thread_ts": {thread_ts},
+	}
+	response, err := api.channelRequest(ctx, "channels.replies", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.History.Messages, nil
+}

backend/vendor/github.com/slack-go/slack/chat.go

@@ -0,0 +1,840 @@
+package slack
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strconv"
+
+	"github.com/slack-go/slack/slackutilsx"
+)
+
+const (
+	DEFAULT_MESSAGE_USERNAME         = ""
+	DEFAULT_MESSAGE_REPLY_BROADCAST  = false
+	DEFAULT_MESSAGE_ASUSER           = false
+	DEFAULT_MESSAGE_PARSE            = ""
+	DEFAULT_MESSAGE_THREAD_TIMESTAMP = ""
+	DEFAULT_MESSAGE_LINK_NAMES       = 0
+	DEFAULT_MESSAGE_UNFURL_LINKS     = false
+	DEFAULT_MESSAGE_UNFURL_MEDIA     = true
+	DEFAULT_MESSAGE_ICON_URL         = ""
+	DEFAULT_MESSAGE_ICON_EMOJI       = ""
+	DEFAULT_MESSAGE_MARKDOWN         = true
+	DEFAULT_MESSAGE_ESCAPE_TEXT      = true
+)
+
+type chatResponseFull struct {
+	Channel            string `json:"channel"`
+	Timestamp          string `json:"ts"`                             //Regular message timestamp
+	MessageTimeStamp   string `json:"message_ts"`                     //Ephemeral message timestamp
+	ScheduledMessageID string `json:"scheduled_message_id,omitempty"` //Scheduled message id
+	Text               string `json:"text"`
+	SlackResponse
+}
+
+// getMessageTimestamp will inspect the `chatResponseFull` to ruturn a timestamp value
+// in `chat.postMessage` its under `ts`
+// in `chat.postEphemeral` its under `message_ts`
+func (c chatResponseFull) getMessageTimestamp() string {
+	if len(c.Timestamp) > 0 {
+		return c.Timestamp
+	}
+	return c.MessageTimeStamp
+}
+
+// PostMessageParameters contains all the parameters necessary (including the optional ones) for a PostMessage() request
+type PostMessageParameters struct {
+	Username        string `json:"username"`
+	AsUser          bool   `json:"as_user"`
+	Parse           string `json:"parse"`
+	ThreadTimestamp string `json:"thread_ts"`
+	ReplyBroadcast  bool   `json:"reply_broadcast"`
+	LinkNames       int    `json:"link_names"`
+	UnfurlLinks     bool   `json:"unfurl_links"`
+	UnfurlMedia     bool   `json:"unfurl_media"`
+	IconURL         string `json:"icon_url"`
+	IconEmoji       string `json:"icon_emoji"`
+	Markdown        bool   `json:"mrkdwn,omitempty"`
+	EscapeText      bool   `json:"escape_text"`
+
+	// chat.postEphemeral support
+	Channel string `json:"channel"`
+	User    string `json:"user"`
+}
+
+// NewPostMessageParameters provides an instance of PostMessageParameters with all the sane default values set
+func NewPostMessageParameters() PostMessageParameters {
+	return PostMessageParameters{
+		Username:        DEFAULT_MESSAGE_USERNAME,
+		User:            DEFAULT_MESSAGE_USERNAME,
+		AsUser:          DEFAULT_MESSAGE_ASUSER,
+		Parse:           DEFAULT_MESSAGE_PARSE,
+		ThreadTimestamp: DEFAULT_MESSAGE_THREAD_TIMESTAMP,
+		LinkNames:       DEFAULT_MESSAGE_LINK_NAMES,
+		UnfurlLinks:     DEFAULT_MESSAGE_UNFURL_LINKS,
+		UnfurlMedia:     DEFAULT_MESSAGE_UNFURL_MEDIA,
+		IconURL:         DEFAULT_MESSAGE_ICON_URL,
+		IconEmoji:       DEFAULT_MESSAGE_ICON_EMOJI,
+		Markdown:        DEFAULT_MESSAGE_MARKDOWN,
+		EscapeText:      DEFAULT_MESSAGE_ESCAPE_TEXT,
+	}
+}
+
+// DeleteMessage deletes a message in a channel
+func (api *Client) DeleteMessage(channel, messageTimestamp string) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(
+		context.Background(),
+		channel,
+		MsgOptionDelete(messageTimestamp),
+	)
+	return respChannel, respTimestamp, err
+}
+
+// DeleteMessageContext deletes a message in a channel with a custom context
+func (api *Client) DeleteMessageContext(ctx context.Context, channel, messageTimestamp string) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(
+		ctx,
+		channel,
+		MsgOptionDelete(messageTimestamp),
+	)
+	return respChannel, respTimestamp, err
+}
+
+// ScheduleMessage sends a message to a channel.
+// Message is escaped by default according to https://api.slack.com/docs/formatting
+// Use http://davestevens.github.io/slack-message-builder/ to help crafting your message.
+func (api *Client) ScheduleMessage(channelID, postAt string, options ...MsgOption) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(
+		context.Background(),
+		channelID,
+		MsgOptionSchedule(postAt),
+		MsgOptionCompose(options...),
+	)
+	return respChannel, respTimestamp, err
+}
+
+// PostMessage sends a message to a channel.
+// Message is escaped by default according to https://api.slack.com/docs/formatting
+// Use http://davestevens.github.io/slack-message-builder/ to help crafting your message.
+func (api *Client) PostMessage(channelID string, options ...MsgOption) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(
+		context.Background(),
+		channelID,
+		MsgOptionPost(),
+		MsgOptionCompose(options...),
+	)
+	return respChannel, respTimestamp, err
+}
+
+// PostMessageContext sends a message to a channel with a custom context
+// For more details, see PostMessage documentation.
+func (api *Client) PostMessageContext(ctx context.Context, channelID string, options ...MsgOption) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(
+		ctx,
+		channelID,
+		MsgOptionPost(),
+		MsgOptionCompose(options...),
+	)
+	return respChannel, respTimestamp, err
+}
+
+// PostEphemeral sends an ephemeral message to a user in a channel.
+// Message is escaped by default according to https://api.slack.com/docs/formatting
+// Use http://davestevens.github.io/slack-message-builder/ to help crafting your message.
+func (api *Client) PostEphemeral(channelID, userID string, options ...MsgOption) (string, error) {
+	return api.PostEphemeralContext(
+		context.Background(),
+		channelID,
+		userID,
+		options...,
+	)
+}
+
+// PostEphemeralContext sends an ephemeal message to a user in a channel with a custom context
+// For more details, see PostEphemeral documentation
+func (api *Client) PostEphemeralContext(ctx context.Context, channelID, userID string, options ...MsgOption) (timestamp string, err error) {
+	_, timestamp, _, err = api.SendMessageContext(
+		ctx,
+		channelID,
+		MsgOptionPostEphemeral(userID),
+		MsgOptionCompose(options...),
+	)
+	return timestamp, err
+}
+
+// UpdateMessage updates a message in a channel
+func (api *Client) UpdateMessage(channelID, timestamp string, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(
+		context.Background(),
+		channelID,
+		MsgOptionUpdate(timestamp),
+		MsgOptionCompose(options...),
+	)
+}
+
+// UpdateMessageContext updates a message in a channel
+func (api *Client) UpdateMessageContext(ctx context.Context, channelID, timestamp string, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(
+		ctx,
+		channelID,
+		MsgOptionUpdate(timestamp),
+		MsgOptionCompose(options...),
+	)
+}
+
+// UnfurlMessage unfurls a message in a channel
+func (api *Client) UnfurlMessage(channelID, timestamp string, unfurls map[string]Attachment, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(context.Background(), channelID, MsgOptionUnfurl(timestamp, unfurls), MsgOptionCompose(options...))
+}
+
+// UnfurlMessageWithAuthURL sends an unfurl request containing an
+// authentication URL.
+// For more details see:
+// https://api.slack.com/reference/messaging/link-unfurling#authenticated_unfurls
+func (api *Client) UnfurlMessageWithAuthURL(channelID, timestamp string, userAuthURL string, options ...MsgOption) (string, string, string, error) {
+	return api.UnfurlMessageWithAuthURLContext(context.Background(), channelID, timestamp, userAuthURL, options...)
+}
+
+// UnfurlMessageWithAuthURLContext sends an unfurl request containing an
+// authentication URL.
+// For more details see:
+// https://api.slack.com/reference/messaging/link-unfurling#authenticated_unfurls
+func (api *Client) UnfurlMessageWithAuthURLContext(ctx context.Context, channelID, timestamp string, userAuthURL string, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(ctx, channelID, MsgOptionUnfurlAuthURL(timestamp, userAuthURL), MsgOptionCompose(options...))
+}
+
+// SendMessage more flexible method for configuring messages.
+func (api *Client) SendMessage(channel string, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(context.Background(), channel, options...)
+}
+
+// SendMessageContext more flexible method for configuring messages with a custom context.
+func (api *Client) SendMessageContext(ctx context.Context, channelID string, options ...MsgOption) (_channel string, _timestamp string, _text string, err error) {
+	var (
+		req      *http.Request
+		parser   func(*chatResponseFull) responseParser
+		response chatResponseFull
+	)
+
+	if req, parser, err = buildSender(api.endpoint, options...).BuildRequest(api.token, channelID); err != nil {
+		return "", "", "", err
+	}
+
+	if api.Debug() {
+		reqBody, err := ioutil.ReadAll(req.Body)
+		if err != nil {
+			return "", "", "", err
+		}
+		req.Body = ioutil.NopCloser(bytes.NewBuffer(reqBody))
+		api.Debugf("Sending request: %s", string(reqBody))
+	}
+
+	if err = doPost(ctx, api.httpclient, req, parser(&response), api); err != nil {
+		return "", "", "", err
+	}
+
+	return response.Channel, response.getMessageTimestamp(), response.Text, response.Err()
+}
+
+// UnsafeApplyMsgOptions utility function for debugging/testing chat requests.
+// NOTE: USE AT YOUR OWN RISK: No issues relating to the use of this function
+// will be supported by the library.
+func UnsafeApplyMsgOptions(token, channel, apiurl string, options ...MsgOption) (string, url.Values, error) {
+	config, err := applyMsgOptions(token, channel, apiurl, options...)
+	return config.endpoint, config.values, err
+}
+
+func applyMsgOptions(token, channel, apiurl string, options ...MsgOption) (sendConfig, error) {
+	config := sendConfig{
+		apiurl:   apiurl,
+		endpoint: apiurl + string(chatPostMessage),
+		values: url.Values{
+			"token":   {token},
+			"channel": {channel},
+		},
+	}
+
+	for _, opt := range options {
+		if err := opt(&config); err != nil {
+			return config, err
+		}
+	}
+
+	return config, nil
+}
+
+func buildSender(apiurl string, options ...MsgOption) sendConfig {
+	return sendConfig{
+		apiurl:  apiurl,
+		options: options,
+	}
+}
+
+type sendMode string
+
+const (
+	chatUpdate          sendMode = "chat.update"
+	chatPostMessage     sendMode = "chat.postMessage"
+	chatScheduleMessage sendMode = "chat.scheduleMessage"
+	chatDelete          sendMode = "chat.delete"
+	chatPostEphemeral   sendMode = "chat.postEphemeral"
+	chatResponse        sendMode = "chat.responseURL"
+	chatMeMessage       sendMode = "chat.meMessage"
+	chatUnfurl          sendMode = "chat.unfurl"
+)
+
+type sendConfig struct {
+	apiurl          string
+	options         []MsgOption
+	mode            sendMode
+	endpoint        string
+	values          url.Values
+	attachments     []Attachment
+	blocks          Blocks
+	responseType    string
+	replaceOriginal bool
+	deleteOriginal  bool
+}
+
+func (t sendConfig) BuildRequest(token, channelID string) (req *http.Request, _ func(*chatResponseFull) responseParser, err error) {
+	if t, err = applyMsgOptions(token, channelID, t.apiurl, t.options...); err != nil {
+		return nil, nil, err
+	}
+
+	switch t.mode {
+	case chatResponse:
+		return responseURLSender{
+			endpoint:        t.endpoint,
+			values:          t.values,
+			attachments:     t.attachments,
+			blocks:          t.blocks,
+			responseType:    t.responseType,
+			replaceOriginal: t.replaceOriginal,
+			deleteOriginal:  t.deleteOriginal,
+		}.BuildRequest()
+	default:
+		return formSender{endpoint: t.endpoint, values: t.values}.BuildRequest()
+	}
+}
+
+type formSender struct {
+	endpoint string
+	values   url.Values
+}
+
+func (t formSender) BuildRequest() (*http.Request, func(*chatResponseFull) responseParser, error) {
+	req, err := formReq(t.endpoint, t.values)
+	return req, func(resp *chatResponseFull) responseParser {
+		return newJSONParser(resp)
+	}, err
+}
+
+type responseURLSender struct {
+	endpoint        string
+	values          url.Values
+	attachments     []Attachment
+	blocks          Blocks
+	responseType    string
+	replaceOriginal bool
+	deleteOriginal  bool
+}
+
+func (t responseURLSender) BuildRequest() (*http.Request, func(*chatResponseFull) responseParser, error) {
+	req, err := jsonReq(t.endpoint, Msg{
+		Text:            t.values.Get("text"),
+		Timestamp:       t.values.Get("ts"),
+		Attachments:     t.attachments,
+		Blocks:          t.blocks,
+		ResponseType:    t.responseType,
+		ReplaceOriginal: t.replaceOriginal,
+		DeleteOriginal:  t.deleteOriginal,
+	})
+	return req, func(resp *chatResponseFull) responseParser {
+		return newContentTypeParser(resp)
+	}, err
+}
+
+// MsgOption option provided when sending a message.
+type MsgOption func(*sendConfig) error
+
+// MsgOptionSchedule schedules a messages.
+func MsgOptionSchedule(postAt string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatScheduleMessage)
+		config.values.Add("post_at", postAt)
+		return nil
+	}
+}
+
+// MsgOptionPost posts a messages, this is the default.
+func MsgOptionPost() MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatPostMessage)
+		config.values.Del("ts")
+		return nil
+	}
+}
+
+// MsgOptionPostEphemeral - posts an ephemeral message to the provided user.
+func MsgOptionPostEphemeral(userID string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatPostEphemeral)
+		MsgOptionUser(userID)(config)
+		config.values.Del("ts")
+
+		return nil
+	}
+}
+
+// MsgOptionMeMessage posts a "me message" type from the calling user
+func MsgOptionMeMessage() MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatMeMessage)
+		return nil
+	}
+}
+
+// MsgOptionUpdate updates a message based on the timestamp.
+func MsgOptionUpdate(timestamp string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatUpdate)
+		config.values.Add("ts", timestamp)
+		return nil
+	}
+}
+
+// MsgOptionDelete deletes a message based on the timestamp.
+func MsgOptionDelete(timestamp string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatDelete)
+		config.values.Add("ts", timestamp)
+		return nil
+	}
+}
+
+// MsgOptionUnfurl unfurls a message based on the timestamp.
+func MsgOptionUnfurl(timestamp string, unfurls map[string]Attachment) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatUnfurl)
+		config.values.Add("ts", timestamp)
+		unfurlsStr, err := json.Marshal(unfurls)
+		if err == nil {
+			config.values.Add("unfurls", string(unfurlsStr))
+		}
+		return err
+	}
+}
+
+// MsgOptionUnfurlAuthURL unfurls a message using an auth url based on the timestamp.
+func MsgOptionUnfurlAuthURL(timestamp string, userAuthURL string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatUnfurl)
+		config.values.Add("ts", timestamp)
+		config.values.Add("user_auth_url", userAuthURL)
+		return nil
+	}
+}
+
+// MsgOptionUnfurlAuthRequired requests that the user installs the
+// Slack app for unfurling.
+func MsgOptionUnfurlAuthRequired(timestamp string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatUnfurl)
+		config.values.Add("ts", timestamp)
+		config.values.Add("user_auth_required", "true")
+		return nil
+	}
+}
+
+// MsgOptionUnfurlAuthMessage attaches a message inviting the user to
+// authenticate.
+func MsgOptionUnfurlAuthMessage(timestamp string, msg string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatUnfurl)
+		config.values.Add("ts", timestamp)
+		config.values.Add("user_auth_message", msg)
+		return nil
+	}
+}
+
+// MsgOptionResponseURL supplies a url to use as the endpoint.
+func MsgOptionResponseURL(url string, responseType string) MsgOption {
+	return func(config *sendConfig) error {
+		config.mode = chatResponse
+		config.endpoint = url
+		config.responseType = responseType
+		config.values.Del("ts")
+		return nil
+	}
+}
+
+// MsgOptionReplaceOriginal replaces original message with response url
+func MsgOptionReplaceOriginal(responseURL string) MsgOption {
+	return func(config *sendConfig) error {
+		config.mode = chatResponse
+		config.endpoint = responseURL
+		config.replaceOriginal = true
+		return nil
+	}
+}
+
+// MsgOptionDeleteOriginal deletes original message with response url
+func MsgOptionDeleteOriginal(responseURL string) MsgOption {
+	return func(config *sendConfig) error {
+		config.mode = chatResponse
+		config.endpoint = responseURL
+		config.deleteOriginal = true
+		return nil
+	}
+}
+
+// MsgOptionAsUser whether or not to send the message as the user.
+func MsgOptionAsUser(b bool) MsgOption {
+	return func(config *sendConfig) error {
+		if b != DEFAULT_MESSAGE_ASUSER {
+			config.values.Set("as_user", "true")
+		}
+		return nil
+	}
+}
+
+// MsgOptionUser set the user for the message.
+func MsgOptionUser(userID string) MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("user", userID)
+		return nil
+	}
+}
+
+// MsgOptionUsername set the username for the message.
+func MsgOptionUsername(username string) MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("username", username)
+		return nil
+	}
+}
+
+// MsgOptionText provide the text for the message, optionally escape the provided
+// text.
+func MsgOptionText(text string, escape bool) MsgOption {
+	return func(config *sendConfig) error {
+		if escape {
+			text = slackutilsx.EscapeMessage(text)
+		}
+		config.values.Add("text", text)
+		return nil
+	}
+}
+
+// MsgOptionAttachments provide attachments for the message.
+func MsgOptionAttachments(attachments ...Attachment) MsgOption {
+	return func(config *sendConfig) error {
+		if attachments == nil {
+			return nil
+		}
+
+		config.attachments = attachments
+
+		// FIXME: We are setting the attachments on the message twice: above for
+		// the json version, and below for the html version.  The marshalled bytes
+		// we put into config.values below don't work directly in the Msg version.
+
+		attachmentBytes, err := json.Marshal(attachments)
+		if err == nil {
+			config.values.Set("attachments", string(attachmentBytes))
+		}
+
+		return err
+	}
+}
+
+// MsgOptionBlocks sets blocks for the message
+func MsgOptionBlocks(blocks ...Block) MsgOption {
+	return func(config *sendConfig) error {
+		if blocks == nil {
+			return nil
+		}
+
+		config.blocks.BlockSet = append(config.blocks.BlockSet, blocks...)
+
+		blocks, err := json.Marshal(blocks)
+		if err == nil {
+			config.values.Set("blocks", string(blocks))
+		}
+		return err
+	}
+}
+
+// MsgOptionEnableLinkUnfurl enables link unfurling
+func MsgOptionEnableLinkUnfurl() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("unfurl_links", "true")
+		return nil
+	}
+}
+
+// MsgOptionDisableLinkUnfurl disables link unfurling
+func MsgOptionDisableLinkUnfurl() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("unfurl_links", "false")
+		return nil
+	}
+}
+
+// MsgOptionDisableMediaUnfurl disables media unfurling.
+func MsgOptionDisableMediaUnfurl() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("unfurl_media", "false")
+		return nil
+	}
+}
+
+// MsgOptionDisableMarkdown disables markdown.
+func MsgOptionDisableMarkdown() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("mrkdwn", "false")
+		return nil
+	}
+}
+
+// MsgOptionTS sets the thread TS of the message to enable creating or replying to a thread
+func MsgOptionTS(ts string) MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("thread_ts", ts)
+		return nil
+	}
+}
+
+// MsgOptionBroadcast sets reply_broadcast to true
+func MsgOptionBroadcast() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("reply_broadcast", "true")
+		return nil
+	}
+}
+
+// MsgOptionCompose combines multiple options into a single option.
+func MsgOptionCompose(options ...MsgOption) MsgOption {
+	return func(config *sendConfig) error {
+		for _, opt := range options {
+			if err := opt(config); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+}
+
+// MsgOptionParse set parse option.
+func MsgOptionParse(b bool) MsgOption {
+	return func(config *sendConfig) error {
+		var v string
+		if b {
+			v = "full"
+		} else {
+			v = "none"
+		}
+		config.values.Set("parse", v)
+		return nil
+	}
+}
+
+// MsgOptionIconURL sets an icon URL
+func MsgOptionIconURL(iconURL string) MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("icon_url", iconURL)
+		return nil
+	}
+}
+
+// MsgOptionIconEmoji sets an icon emoji
+func MsgOptionIconEmoji(iconEmoji string) MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("icon_emoji", iconEmoji)
+		return nil
+	}
+}
+
+// UnsafeMsgOptionEndpoint deliver the message to the specified endpoint.
+// NOTE: USE AT YOUR OWN RISK: No issues relating to the use of this Option
+// will be supported by the library, it is subject to change without notice that
+// may result in compilation errors or runtime behaviour changes.
+func UnsafeMsgOptionEndpoint(endpoint string, update func(url.Values)) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = endpoint
+		update(config.values)
+		return nil
+	}
+}
+
+// MsgOptionPostMessageParameters maintain backwards compatibility.
+func MsgOptionPostMessageParameters(params PostMessageParameters) MsgOption {
+	return func(config *sendConfig) error {
+		if params.Username != DEFAULT_MESSAGE_USERNAME {
+			config.values.Set("username", params.Username)
+		}
+
+		// chat.postEphemeral support
+		if params.User != DEFAULT_MESSAGE_USERNAME {
+			config.values.Set("user", params.User)
+		}
+
+		// never generates an error.
+		MsgOptionAsUser(params.AsUser)(config)
+
+		if params.Parse != DEFAULT_MESSAGE_PARSE {
+			config.values.Set("parse", params.Parse)
+		}
+		if params.LinkNames != DEFAULT_MESSAGE_LINK_NAMES {
+			config.values.Set("link_names", "1")
+		}
+
+		if params.UnfurlLinks != DEFAULT_MESSAGE_UNFURL_LINKS {
+			config.values.Set("unfurl_links", "true")
+		}
+
+		// I want to send a message with explicit `as_user` `true` and `unfurl_links` `false` in request.
+		// Because setting `as_user` to `true` will change the default value for `unfurl_links` to `true` on Slack API side.
+		if params.AsUser != DEFAULT_MESSAGE_ASUSER && params.UnfurlLinks == DEFAULT_MESSAGE_UNFURL_LINKS {
+			config.values.Set("unfurl_links", "false")
+		}
+		if params.UnfurlMedia != DEFAULT_MESSAGE_UNFURL_MEDIA {
+			config.values.Set("unfurl_media", "false")
+		}
+		if params.IconURL != DEFAULT_MESSAGE_ICON_URL {
+			config.values.Set("icon_url", params.IconURL)
+		}
+		if params.IconEmoji != DEFAULT_MESSAGE_ICON_EMOJI {
+			config.values.Set("icon_emoji", params.IconEmoji)
+		}
+		if params.Markdown != DEFAULT_MESSAGE_MARKDOWN {
+			config.values.Set("mrkdwn", "false")
+		}
+
+		if params.ThreadTimestamp != DEFAULT_MESSAGE_THREAD_TIMESTAMP {
+			config.values.Set("thread_ts", params.ThreadTimestamp)
+		}
+		if params.ReplyBroadcast != DEFAULT_MESSAGE_REPLY_BROADCAST {
+			config.values.Set("reply_broadcast", "true")
+		}
+
+		return nil
+	}
+}
+
+// PermalinkParameters are the parameters required to get a permalink to a
+// message. Slack documentation can be found here:
+// https://api.slack.com/methods/chat.getPermalink
+type PermalinkParameters struct {
+	Channel string
+	Ts      string
+}
+
+// GetPermalink returns the permalink for a message. It takes
+// PermalinkParameters and returns a string containing the permalink. It
+// returns an error if unable to retrieve the permalink.
+func (api *Client) GetPermalink(params *PermalinkParameters) (string, error) {
+	return api.GetPermalinkContext(context.Background(), params)
+}
+
+// GetPermalinkContext returns the permalink for a message using a custom context.
+func (api *Client) GetPermalinkContext(ctx context.Context, params *PermalinkParameters) (string, error) {
+	values := url.Values{
+		"token":      {api.token},
+		"channel":    {params.Channel},
+		"message_ts": {params.Ts},
+	}
+
+	response := struct {
+		Channel   string `json:"channel"`
+		Permalink string `json:"permalink"`
+		SlackResponse
+	}{}
+	err := api.getMethod(ctx, "chat.getPermalink", values, &response)
+	if err != nil {
+		return "", err
+	}
+	return response.Permalink, response.Err()
+}
+
+type GetScheduledMessagesParameters struct {
+	Channel string
+	Cursor  string
+	Latest  string
+	Limit   int
+	Oldest  string
+}
+
+// GetScheduledMessages returns the list of scheduled messages based on params
+func (api *Client) GetScheduledMessages(params *GetScheduledMessagesParameters) (channels []ScheduledMessage, nextCursor string, err error) {
+	return api.GetScheduledMessagesContext(context.Background(), params)
+}
+
+// GetScheduledMessagesContext returns the list of scheduled messages in a Slack team with a custom context
+func (api *Client) GetScheduledMessagesContext(ctx context.Context, params *GetScheduledMessagesParameters) (channels []ScheduledMessage, nextCursor string, err error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.Channel != "" {
+		values.Add("channel", params.Channel)
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Latest != "" {
+		values.Add("latest", params.Latest)
+	}
+	if params.Oldest != "" {
+		values.Add("oldest", params.Oldest)
+	}
+	response := struct {
+		Messages         []ScheduledMessage `json:"scheduled_messages"`
+		ResponseMetaData responseMetaData   `json:"response_metadata"`
+		SlackResponse
+	}{}
+
+	err = api.postMethod(ctx, "chat.scheduledMessages.list", values, &response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	return response.Messages, response.ResponseMetaData.NextCursor, response.Err()
+}
+
+type DeleteScheduledMessageParameters struct {
+	Channel            string
+	ScheduledMessageID string
+	AsUser             bool
+}
+
+// DeleteScheduledMessage returns the list of scheduled messages based on params
+func (api *Client) DeleteScheduledMessage(params *DeleteScheduledMessageParameters) (bool, error) {
+	return api.DeleteScheduledMessageContext(context.Background(), params)
+}
+
+// DeleteScheduledMessageContext returns the list of scheduled messages in a Slack team with a custom context
+func (api *Client) DeleteScheduledMessageContext(ctx context.Context, params *DeleteScheduledMessageParameters) (bool, error) {
+	values := url.Values{
+		"token":                {api.token},
+		"channel":              {params.Channel},
+		"scheduled_message_id": {params.ScheduledMessageID},
+		"as_user":              {strconv.FormatBool(params.AsUser)},
+	}
+	response := struct {
+		SlackResponse
+	}{}
+
+	err := api.postMethod(ctx, "chat.deleteScheduledMessage", values, &response)
+	if err != nil {
+		return false, err
+	}
+
+	return response.Ok, response.Err()
+}

backend/vendor/github.com/slack-go/slack/comment.go

@@ -0,0 +1,10 @@
+package slack
+
+// Comment contains all the information relative to a comment
+type Comment struct {
+	ID        string   `json:"id,omitempty"`
+	Created   JSONTime `json:"created,omitempty"`
+	Timestamp JSONTime `json:"timestamp,omitempty"`
+	User      string   `json:"user,omitempty"`
+	Comment   string   `json:"comment,omitempty"`
+}

backend/vendor/github.com/slack-go/slack/conversation.go

@@ -0,0 +1,645 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+// Conversation is the foundation for IM and BaseGroupConversation
+type Conversation struct {
+	ID                 string   `json:"id"`
+	Created            JSONTime `json:"created"`
+	IsOpen             bool     `json:"is_open"`
+	LastRead           string   `json:"last_read,omitempty"`
+	Latest             *Message `json:"latest,omitempty"`
+	UnreadCount        int      `json:"unread_count,omitempty"`
+	UnreadCountDisplay int      `json:"unread_count_display,omitempty"`
+	IsGroup            bool     `json:"is_group"`
+	IsShared           bool     `json:"is_shared"`
+	IsIM               bool     `json:"is_im"`
+	IsExtShared        bool     `json:"is_ext_shared"`
+	IsOrgShared        bool     `json:"is_org_shared"`
+	IsPendingExtShared bool     `json:"is_pending_ext_shared"`
+	IsPrivate          bool     `json:"is_private"`
+	IsMpIM             bool     `json:"is_mpim"`
+	Unlinked           int      `json:"unlinked"`
+	NameNormalized     string   `json:"name_normalized"`
+	NumMembers         int      `json:"num_members"`
+	Priority           float64  `json:"priority"`
+	User               string   `json:"user"`
+
+	// TODO support pending_shared
+	// TODO support previous_names
+}
+
+// GroupConversation is the foundation for Group and Channel
+type GroupConversation struct {
+	Conversation
+	Name       string   `json:"name"`
+	Creator    string   `json:"creator"`
+	IsArchived bool     `json:"is_archived"`
+	Members    []string `json:"members"`
+	Topic      Topic    `json:"topic"`
+	Purpose    Purpose  `json:"purpose"`
+}
+
+// Topic contains information about the topic
+type Topic struct {
+	Value   string   `json:"value"`
+	Creator string   `json:"creator"`
+	LastSet JSONTime `json:"last_set"`
+}
+
+// Purpose contains information about the purpose
+type Purpose struct {
+	Value   string   `json:"value"`
+	Creator string   `json:"creator"`
+	LastSet JSONTime `json:"last_set"`
+}
+
+type GetUsersInConversationParameters struct {
+	ChannelID string
+	Cursor    string
+	Limit     int
+}
+
+type GetConversationsForUserParameters struct {
+	UserID          string
+	Cursor          string
+	Types           []string
+	Limit           int
+	ExcludeArchived bool
+}
+
+type responseMetaData struct {
+	NextCursor string `json:"next_cursor"`
+}
+
+// GetUsersInConversation returns the list of users in a conversation
+func (api *Client) GetUsersInConversation(params *GetUsersInConversationParameters) ([]string, string, error) {
+	return api.GetUsersInConversationContext(context.Background(), params)
+}
+
+// GetUsersInConversationContext returns the list of users in a conversation with a custom context
+func (api *Client) GetUsersInConversationContext(ctx context.Context, params *GetUsersInConversationParameters) ([]string, string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {params.ChannelID},
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	response := struct {
+		Members          []string         `json:"members"`
+		ResponseMetaData responseMetaData `json:"response_metadata"`
+		SlackResponse
+	}{}
+
+	err := api.postMethod(ctx, "conversations.members", values, &response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, "", err
+	}
+
+	return response.Members, response.ResponseMetaData.NextCursor, nil
+}
+
+// GetConversationsForUser returns the list conversations for a given user
+func (api *Client) GetConversationsForUser(params *GetConversationsForUserParameters) (channels []Channel, nextCursor string, err error) {
+	return api.GetConversationsForUserContext(context.Background(), params)
+}
+
+// GetConversationsForUserContext returns the list conversations for a given user with a custom context
+func (api *Client) GetConversationsForUserContext(ctx context.Context, params *GetConversationsForUserParameters) (channels []Channel, nextCursor string, err error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.UserID != "" {
+		values.Add("user", params.UserID)
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Types != nil {
+		values.Add("types", strings.Join(params.Types, ","))
+	}
+	if params.ExcludeArchived {
+		values.Add("exclude_archived", "true")
+	}
+	response := struct {
+		Channels         []Channel        `json:"channels"`
+		ResponseMetaData responseMetaData `json:"response_metadata"`
+		SlackResponse
+	}{}
+	err = api.postMethod(ctx, "users.conversations", values, &response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	return response.Channels, response.ResponseMetaData.NextCursor, response.Err()
+}
+
+// ArchiveConversation archives a conversation
+func (api *Client) ArchiveConversation(channelID string) error {
+	return api.ArchiveConversationContext(context.Background(), channelID)
+}
+
+// ArchiveConversationContext archives a conversation with a custom context
+func (api *Client) ArchiveConversationContext(ctx context.Context, channelID string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	response := SlackResponse{}
+	err := api.postMethod(ctx, "conversations.archive", values, &response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// UnArchiveConversation reverses conversation archival
+func (api *Client) UnArchiveConversation(channelID string) error {
+	return api.UnArchiveConversationContext(context.Background(), channelID)
+}
+
+// UnArchiveConversationContext reverses conversation archival with a custom context
+func (api *Client) UnArchiveConversationContext(ctx context.Context, channelID string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+	response := SlackResponse{}
+	err := api.postMethod(ctx, "conversations.unarchive", values, &response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// SetTopicOfConversation sets the topic for a conversation
+func (api *Client) SetTopicOfConversation(channelID, topic string) (*Channel, error) {
+	return api.SetTopicOfConversationContext(context.Background(), channelID, topic)
+}
+
+// SetTopicOfConversationContext sets the topic for a conversation with a custom context
+func (api *Client) SetTopicOfConversationContext(ctx context.Context, channelID, topic string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"topic":   {topic},
+	}
+	response := struct {
+		SlackResponse
+		Channel *Channel `json:"channel"`
+	}{}
+	err := api.postMethod(ctx, "conversations.setTopic", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.Channel, response.Err()
+}
+
+// SetPurposeOfConversation sets the purpose for a conversation
+func (api *Client) SetPurposeOfConversation(channelID, purpose string) (*Channel, error) {
+	return api.SetPurposeOfConversationContext(context.Background(), channelID, purpose)
+}
+
+// SetPurposeOfConversationContext sets the purpose for a conversation with a custom context
+func (api *Client) SetPurposeOfConversationContext(ctx context.Context, channelID, purpose string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"purpose": {purpose},
+	}
+	response := struct {
+		SlackResponse
+		Channel *Channel `json:"channel"`
+	}{}
+
+	err := api.postMethod(ctx, "conversations.setPurpose", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.Channel, response.Err()
+}
+
+// RenameConversation renames a conversation
+func (api *Client) RenameConversation(channelID, channelName string) (*Channel, error) {
+	return api.RenameConversationContext(context.Background(), channelID, channelName)
+}
+
+// RenameConversationContext renames a conversation with a custom context
+func (api *Client) RenameConversationContext(ctx context.Context, channelID, channelName string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"name":    {channelName},
+	}
+	response := struct {
+		SlackResponse
+		Channel *Channel `json:"channel"`
+	}{}
+
+	err := api.postMethod(ctx, "conversations.rename", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.Channel, response.Err()
+}
+
+// InviteUsersToConversation invites users to a channel
+func (api *Client) InviteUsersToConversation(channelID string, users ...string) (*Channel, error) {
+	return api.InviteUsersToConversationContext(context.Background(), channelID, users...)
+}
+
+// InviteUsersToConversationContext invites users to a channel with a custom context
+func (api *Client) InviteUsersToConversationContext(ctx context.Context, channelID string, users ...string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"users":   {strings.Join(users, ",")},
+	}
+	response := struct {
+		SlackResponse
+		Channel *Channel `json:"channel"`
+	}{}
+
+	err := api.postMethod(ctx, "conversations.invite", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.Channel, response.Err()
+}
+
+// KickUserFromConversation removes a user from a conversation
+func (api *Client) KickUserFromConversation(channelID string, user string) error {
+	return api.KickUserFromConversationContext(context.Background(), channelID, user)
+}
+
+// KickUserFromConversationContext removes a user from a conversation with a custom context
+func (api *Client) KickUserFromConversationContext(ctx context.Context, channelID string, user string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"user":    {user},
+	}
+
+	response := SlackResponse{}
+	err := api.postMethod(ctx, "conversations.kick", values, &response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// CloseConversation closes a direct message or multi-person direct message
+func (api *Client) CloseConversation(channelID string) (noOp bool, alreadyClosed bool, err error) {
+	return api.CloseConversationContext(context.Background(), channelID)
+}
+
+// CloseConversationContext closes a direct message or multi-person direct message with a custom context
+func (api *Client) CloseConversationContext(ctx context.Context, channelID string) (noOp bool, alreadyClosed bool, err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+	response := struct {
+		SlackResponse
+		NoOp          bool `json:"no_op"`
+		AlreadyClosed bool `json:"already_closed"`
+	}{}
+
+	err = api.postMethod(ctx, "conversations.close", values, &response)
+	if err != nil {
+		return false, false, err
+	}
+
+	return response.NoOp, response.AlreadyClosed, response.Err()
+}
+
+// CreateConversation initiates a public or private channel-based conversation
+func (api *Client) CreateConversation(channelName string, isPrivate bool) (*Channel, error) {
+	return api.CreateConversationContext(context.Background(), channelName, isPrivate)
+}
+
+// CreateConversationContext initiates a public or private channel-based conversation with a custom context
+func (api *Client) CreateConversationContext(ctx context.Context, channelName string, isPrivate bool) (*Channel, error) {
+	values := url.Values{
+		"token":      {api.token},
+		"name":       {channelName},
+		"is_private": {strconv.FormatBool(isPrivate)},
+	}
+	response, err := api.channelRequest(ctx, "conversations.create", values)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response.Channel, nil
+}
+
+// GetConversationInfo retrieves information about a conversation
+func (api *Client) GetConversationInfo(channelID string, includeLocale bool) (*Channel, error) {
+	return api.GetConversationInfoContext(context.Background(), channelID, includeLocale)
+}
+
+// GetConversationInfoContext retrieves information about a conversation with a custom context
+func (api *Client) GetConversationInfoContext(ctx context.Context, channelID string, includeLocale bool) (*Channel, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"channel":        {channelID},
+		"include_locale": {strconv.FormatBool(includeLocale)},
+	}
+	response, err := api.channelRequest(ctx, "conversations.info", values)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response.Channel, response.Err()
+}
+
+// LeaveConversation leaves a conversation
+func (api *Client) LeaveConversation(channelID string) (bool, error) {
+	return api.LeaveConversationContext(context.Background(), channelID)
+}
+
+// LeaveConversationContext leaves a conversation with a custom context
+func (api *Client) LeaveConversationContext(ctx context.Context, channelID string) (bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	response, err := api.channelRequest(ctx, "conversations.leave", values)
+	if err != nil {
+		return false, err
+	}
+
+	return response.NotInChannel, err
+}
+
+type GetConversationRepliesParameters struct {
+	ChannelID string
+	Timestamp string
+	Cursor    string
+	Inclusive bool
+	Latest    string
+	Limit     int
+	Oldest    string
+}
+
+// GetConversationReplies retrieves a thread of messages posted to a conversation
+func (api *Client) GetConversationReplies(params *GetConversationRepliesParameters) (msgs []Message, hasMore bool, nextCursor string, err error) {
+	return api.GetConversationRepliesContext(context.Background(), params)
+}
+
+// GetConversationRepliesContext retrieves a thread of messages posted to a conversation with a custom context
+func (api *Client) GetConversationRepliesContext(ctx context.Context, params *GetConversationRepliesParameters) (msgs []Message, hasMore bool, nextCursor string, err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {params.ChannelID},
+		"ts":      {params.Timestamp},
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Latest != "" {
+		values.Add("latest", params.Latest)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Oldest != "" {
+		values.Add("oldest", params.Oldest)
+	}
+	if params.Inclusive {
+		values.Add("inclusive", "1")
+	} else {
+		values.Add("inclusive", "0")
+	}
+	response := struct {
+		SlackResponse
+		HasMore          bool `json:"has_more"`
+		ResponseMetaData struct {
+			NextCursor string `json:"next_cursor"`
+		} `json:"response_metadata"`
+		Messages []Message `json:"messages"`
+	}{}
+
+	err = api.postMethod(ctx, "conversations.replies", values, &response)
+	if err != nil {
+		return nil, false, "", err
+	}
+
+	return response.Messages, response.HasMore, response.ResponseMetaData.NextCursor, response.Err()
+}
+
+type GetConversationsParameters struct {
+	Cursor          string
+	ExcludeArchived string
+	Limit           int
+	Types           []string
+}
+
+// GetConversations returns the list of channels in a Slack team
+func (api *Client) GetConversations(params *GetConversationsParameters) (channels []Channel, nextCursor string, err error) {
+	return api.GetConversationsContext(context.Background(), params)
+}
+
+// GetConversationsContext returns the list of channels in a Slack team with a custom context
+func (api *Client) GetConversationsContext(ctx context.Context, params *GetConversationsParameters) (channels []Channel, nextCursor string, err error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Types != nil {
+		values.Add("types", strings.Join(params.Types, ","))
+	}
+	if params.ExcludeArchived == "true" {
+		values.Add("exclude_archived", "true")
+	}
+
+	response := struct {
+		Channels         []Channel        `json:"channels"`
+		ResponseMetaData responseMetaData `json:"response_metadata"`
+		SlackResponse
+	}{}
+
+	err = api.postMethod(ctx, "conversations.list", values, &response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	return response.Channels, response.ResponseMetaData.NextCursor, response.Err()
+}
+
+type OpenConversationParameters struct {
+	ChannelID string
+	ReturnIM  bool
+	Users     []string
+}
+
+// OpenConversation opens or resumes a direct message or multi-person direct message
+func (api *Client) OpenConversation(params *OpenConversationParameters) (*Channel, bool, bool, error) {
+	return api.OpenConversationContext(context.Background(), params)
+}
+
+// OpenConversationContext opens or resumes a direct message or multi-person direct message with a custom context
+func (api *Client) OpenConversationContext(ctx context.Context, params *OpenConversationParameters) (*Channel, bool, bool, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"return_im": {strconv.FormatBool(params.ReturnIM)},
+	}
+	if params.ChannelID != "" {
+		values.Add("channel", params.ChannelID)
+	}
+	if params.Users != nil {
+		values.Add("users", strings.Join(params.Users, ","))
+	}
+	response := struct {
+		Channel     *Channel `json:"channel"`
+		NoOp        bool     `json:"no_op"`
+		AlreadyOpen bool     `json:"already_open"`
+		SlackResponse
+	}{}
+
+	err := api.postMethod(ctx, "conversations.open", values, &response)
+	if err != nil {
+		return nil, false, false, err
+	}
+
+	return response.Channel, response.NoOp, response.AlreadyOpen, response.Err()
+}
+
+// JoinConversation joins an existing conversation
+func (api *Client) JoinConversation(channelID string) (*Channel, string, []string, error) {
+	return api.JoinConversationContext(context.Background(), channelID)
+}
+
+// JoinConversationContext joins an existing conversation with a custom context
+func (api *Client) JoinConversationContext(ctx context.Context, channelID string) (*Channel, string, []string, error) {
+	values := url.Values{"token": {api.token}, "channel": {channelID}}
+	response := struct {
+		Channel          *Channel `json:"channel"`
+		Warning          string   `json:"warning"`
+		ResponseMetaData *struct {
+			Warnings []string `json:"warnings"`
+		} `json:"response_metadata"`
+		SlackResponse
+	}{}
+
+	err := api.postMethod(ctx, "conversations.join", values, &response)
+	if err != nil {
+		return nil, "", nil, err
+	}
+	if response.Err() != nil {
+		return nil, "", nil, response.Err()
+	}
+	var warnings []string
+	if response.ResponseMetaData != nil {
+		warnings = response.ResponseMetaData.Warnings
+	}
+	return response.Channel, response.Warning, warnings, nil
+}
+
+type GetConversationHistoryParameters struct {
+	ChannelID string
+	Cursor    string
+	Inclusive bool
+	Latest    string
+	Limit     int
+	Oldest    string
+}
+
+type GetConversationHistoryResponse struct {
+	SlackResponse
+	HasMore          bool   `json:"has_more"`
+	PinCount         int    `json:"pin_count"`
+	Latest           string `json:"latest"`
+	ResponseMetaData struct {
+		NextCursor string `json:"next_cursor"`
+	} `json:"response_metadata"`
+	Messages []Message `json:"messages"`
+}
+
+// GetConversationHistory joins an existing conversation
+func (api *Client) GetConversationHistory(params *GetConversationHistoryParameters) (*GetConversationHistoryResponse, error) {
+	return api.GetConversationHistoryContext(context.Background(), params)
+}
+
+// GetConversationHistoryContext joins an existing conversation with a custom context
+func (api *Client) GetConversationHistoryContext(ctx context.Context, params *GetConversationHistoryParameters) (*GetConversationHistoryResponse, error) {
+	values := url.Values{"token": {api.token}, "channel": {params.ChannelID}}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Inclusive {
+		values.Add("inclusive", "1")
+	} else {
+		values.Add("inclusive", "0")
+	}
+	if params.Latest != "" {
+		values.Add("latest", params.Latest)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Oldest != "" {
+		values.Add("oldest", params.Oldest)
+	}
+
+	response := GetConversationHistoryResponse{}
+
+	err := api.postMethod(ctx, "conversations.history", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response, response.Err()
+}
+
+// MarkConversation sets the read mark of a conversation to a specific point
+func (api *Client) MarkConversation(channel, ts string) (err error) {
+	return api.MarkConversationContext(context.Background(), channel, ts)
+}
+
+// MarkConversationContext sets the read mark of a conversation to a specific point with a custom context
+func (api *Client) MarkConversationContext(ctx context.Context, channel, ts string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channel},
+		"ts":      {ts},
+	}
+
+	response := &SlackResponse{}
+
+	err := api.postMethod(ctx, "conversations.mark", values, response)
+	if err != nil {
+		return err
+	}
+	return response.Err()
+}

backend/vendor/github.com/slack-go/slack/dialog.go

@@ -0,0 +1,120 @@
+package slack
+
+import (
+	"context"
+	"encoding/json"
+	"strings"
+)
+
+// InputType is the type of the dialog input type
+type InputType string
+
+const (
+	// InputTypeText textfield input
+	InputTypeText InputType = "text"
+	// InputTypeTextArea textarea input
+	InputTypeTextArea InputType = "textarea"
+	// InputTypeSelect select menus input
+	InputTypeSelect InputType = "select"
+)
+
+// DialogInput for dialogs input type text or menu
+type DialogInput struct {
+	Type        InputType `json:"type"`
+	Label       string    `json:"label"`
+	Name        string    `json:"name"`
+	Placeholder string    `json:"placeholder"`
+	Optional    bool      `json:"optional"`
+	Hint        string    `json:"hint"`
+}
+
+// DialogTrigger ...
+type DialogTrigger struct {
+	TriggerID string `json:"trigger_id"` //Required. Must respond within 3 seconds.
+	Dialog    Dialog `json:"dialog"`     //Required.
+}
+
+// Dialog as in Slack dialogs
+// https://api.slack.com/dialogs#option_element_attributes#top-level_dialog_attributes
+type Dialog struct {
+	TriggerID      string          `json:"trigger_id"`      // Required
+	CallbackID     string          `json:"callback_id"`     // Required
+	State          string          `json:"state,omitempty"` // Optional
+	Title          string          `json:"title"`
+	SubmitLabel    string          `json:"submit_label,omitempty"`
+	NotifyOnCancel bool            `json:"notify_on_cancel"`
+	Elements       []DialogElement `json:"elements"`
+}
+
+// DialogElement abstract type for dialogs.
+type DialogElement interface{}
+
+// DialogCallback DEPRECATED use InteractionCallback
+type DialogCallback InteractionCallback
+
+// DialogSubmissionCallback is sent from Slack when a user submits a form from within a dialog
+type DialogSubmissionCallback struct {
+	// NOTE: State is only used with the dialog_submission type.
+	// You should use InteractionCallback.BlockActionsState for block_actions type.
+	State      string            `json:"-"`
+	Submission map[string]string `json:"submission"`
+}
+
+// DialogOpenResponse response from `dialog.open`
+type DialogOpenResponse struct {
+	SlackResponse
+	DialogResponseMetadata DialogResponseMetadata `json:"response_metadata"`
+}
+
+// DialogResponseMetadata lists the error messages
+type DialogResponseMetadata struct {
+	Messages []string `json:"messages"`
+}
+
+// DialogInputValidationError is an error when user inputs incorrect value to form from within a dialog
+type DialogInputValidationError struct {
+	Name  string `json:"name"`
+	Error string `json:"error"`
+}
+
+// DialogInputValidationErrors lists the name of field and that error messages
+type DialogInputValidationErrors struct {
+	Errors []DialogInputValidationError `json:"errors"`
+}
+
+// OpenDialog opens a dialog window where the triggerID originated from.
+// EXPERIMENTAL: dialog functionality is currently experimental, api is not considered stable.
+func (api *Client) OpenDialog(triggerID string, dialog Dialog) (err error) {
+	return api.OpenDialogContext(context.Background(), triggerID, dialog)
+}
+
+// OpenDialogContext opens a dialog window where the triggerId originated from with a custom context
+// EXPERIMENTAL: dialog functionality is currently experimental, api is not considered stable.
+func (api *Client) OpenDialogContext(ctx context.Context, triggerID string, dialog Dialog) (err error) {
+	if triggerID == "" {
+		return ErrParametersMissing
+	}
+
+	req := DialogTrigger{
+		TriggerID: triggerID,
+		Dialog:    dialog,
+	}
+
+	encoded, err := json.Marshal(req)
+	if err != nil {
+		return err
+	}
+
+	response := &DialogOpenResponse{}
+	endpoint := api.endpoint + "dialog.open"
+	if err := postJSON(ctx, api.httpclient, endpoint, api.token, encoded, response, api); err != nil {
+		return err
+	}
+
+	if len(response.DialogResponseMetadata.Messages) > 0 {
+		response.Ok = false
+		response.Error += "\n" + strings.Join(response.DialogResponseMetadata.Messages, "\n")
+	}
+
+	return response.Err()
+}

backend/vendor/github.com/slack-go/slack/dialog_select.go

@@ -0,0 +1,101 @@
+package slack
+
+// SelectDataSource types of select datasource
+type SelectDataSource string
+
+const (
+	// DialogDataSourceStatic menu with static Options/OptionGroups
+	DialogDataSourceStatic SelectDataSource = "static"
+	// DialogDataSourceExternal dynamic datasource
+	DialogDataSourceExternal SelectDataSource = "external"
+	// DialogDataSourceConversations provides a list of conversations
+	DialogDataSourceConversations SelectDataSource = "conversations"
+	// DialogDataSourceChannels provides a list of channels
+	DialogDataSourceChannels SelectDataSource = "channels"
+	// DialogDataSourceUsers provides a list of users
+	DialogDataSourceUsers SelectDataSource = "users"
+)
+
+// DialogInputSelect dialog support for select boxes.
+type DialogInputSelect struct {
+	DialogInput
+	Value           string               `json:"value,omitempty"`            //Optional.
+	DataSource      SelectDataSource     `json:"data_source,omitempty"`      //Optional. Allowed values: "users", "channels", "conversations", "external".
+	SelectedOptions []DialogSelectOption `json:"selected_options,omitempty"` //Optional. May hold at most one element, for use with "external" only.
+	Options         []DialogSelectOption `json:"options,omitempty"`          //One of options or option_groups is required.
+	OptionGroups    []DialogOptionGroup  `json:"option_groups,omitempty"`    //Provide up to 100 options.
+	MinQueryLength  int                  `json:"min_query_length,omitempty"` //Optional. minimum characters before query is sent.
+	Hint            string               `json:"hint,omitempty"`             //Optional. Additional hint text.
+}
+
+// DialogSelectOption is an option for the user to select from the menu
+type DialogSelectOption struct {
+	Label string `json:"label"`
+	Value string `json:"value"`
+}
+
+// DialogOptionGroup is a collection of options for creating a segmented table
+type DialogOptionGroup struct {
+	Label   string               `json:"label"`
+	Options []DialogSelectOption `json:"options"`
+}
+
+// NewStaticSelectDialogInput constructor for a `static` datasource menu input
+func NewStaticSelectDialogInput(name, label string, options []DialogSelectOption) *DialogInputSelect {
+	return &DialogInputSelect{
+		DialogInput: DialogInput{
+			Type:     InputTypeSelect,
+			Name:     name,
+			Label:    label,
+			Optional: true,
+		},
+		DataSource: DialogDataSourceStatic,
+		Options:    options,
+	}
+}
+
+// NewGroupedSelectDialogInput creates grouped options select input for Dialogs.
+func NewGroupedSelectDialogInput(name, label string, options []DialogOptionGroup) *DialogInputSelect {
+	return &DialogInputSelect{
+		DialogInput: DialogInput{
+			Type:  InputTypeSelect,
+			Name:  name,
+			Label: label,
+		},
+		DataSource:   DialogDataSourceStatic,
+		OptionGroups: options}
+}
+
+// NewDialogOptionGroup creates a DialogOptionGroup from several select options
+func NewDialogOptionGroup(label string, options ...DialogSelectOption) DialogOptionGroup {
+	return DialogOptionGroup{
+		Label:   label,
+		Options: options,
+	}
+}
+
+// NewConversationsSelect returns a `Conversations` select
+func NewConversationsSelect(name, label string) *DialogInputSelect {
+	return newPresetSelect(name, label, DialogDataSourceConversations)
+}
+
+// NewChannelsSelect returns a `Channels` select
+func NewChannelsSelect(name, label string) *DialogInputSelect {
+	return newPresetSelect(name, label, DialogDataSourceChannels)
+}
+
+// NewUsersSelect returns a `Users` select
+func NewUsersSelect(name, label string) *DialogInputSelect {
+	return newPresetSelect(name, label, DialogDataSourceUsers)
+}
+
+func newPresetSelect(name, label string, dataSourceType SelectDataSource) *DialogInputSelect {
+	return &DialogInputSelect{
+		DialogInput: DialogInput{
+			Type:  InputTypeSelect,
+			Label: label,
+			Name:  name,
+		},
+		DataSource: dataSourceType,
+	}
+}

backend/vendor/github.com/slack-go/slack/dialog_text.go

@@ -0,0 +1,59 @@
+package slack
+
+// TextInputSubtype Accepts email, number, tel, or url. In some form factors, optimized input is provided for this subtype.
+type TextInputSubtype string
+
+// TextInputOption handle to extra inputs options.
+type TextInputOption func(*TextInputElement)
+
+const (
+	// InputSubtypeEmail email keyboard
+	InputSubtypeEmail TextInputSubtype = "email"
+	// InputSubtypeNumber numeric keyboard
+	InputSubtypeNumber TextInputSubtype = "number"
+	// InputSubtypeTel Phone keyboard
+	InputSubtypeTel TextInputSubtype = "tel"
+	// InputSubtypeURL Phone keyboard
+	InputSubtypeURL TextInputSubtype = "url"
+)
+
+// TextInputElement subtype of DialogInput
+//	https://api.slack.com/dialogs#option_element_attributes#text_element_attributes
+type TextInputElement struct {
+	DialogInput
+	MaxLength int              `json:"max_length,omitempty"`
+	MinLength int              `json:"min_length,omitempty"`
+	Hint      string           `json:"hint,omitempty"`
+	Subtype   TextInputSubtype `json:"subtype"`
+	Value     string           `json:"value"`
+}
+
+// NewTextInput constructor for a `text` input
+func NewTextInput(name, label, text string, options ...TextInputOption) *TextInputElement {
+	t := &TextInputElement{
+		DialogInput: DialogInput{
+			Type:  InputTypeText,
+			Name:  name,
+			Label: label,
+		},
+		Value: text,
+	}
+
+	for _, opt := range options {
+		opt(t)
+	}
+
+	return t
+}
+
+// NewTextAreaInput constructor for a `textarea` input
+func NewTextAreaInput(name, label, text string) *TextInputElement {
+	return &TextInputElement{
+		DialogInput: DialogInput{
+			Type:  InputTypeTextArea,
+			Name:  name,
+			Label: label,
+		},
+		Value: text,
+	}
+}

backend/vendor/github.com/slack-go/slack/dnd.go

@@ -0,0 +1,151 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+type SnoozeDebug struct {
+	SnoozeEndDate string `json:"snooze_end_date"`
+}
+
+type SnoozeInfo struct {
+	SnoozeEnabled   bool        `json:"snooze_enabled,omitempty"`
+	SnoozeEndTime   int         `json:"snooze_endtime,omitempty"`
+	SnoozeRemaining int         `json:"snooze_remaining,omitempty"`
+	SnoozeDebug     SnoozeDebug `json:"snooze_debug,omitempty"`
+}
+
+type DNDStatus struct {
+	Enabled            bool `json:"dnd_enabled"`
+	NextStartTimestamp int  `json:"next_dnd_start_ts"`
+	NextEndTimestamp   int  `json:"next_dnd_end_ts"`
+	SnoozeInfo
+}
+
+type dndResponseFull struct {
+	DNDStatus
+	SlackResponse
+}
+
+type dndTeamInfoResponse struct {
+	Users map[string]DNDStatus `json:"users"`
+	SlackResponse
+}
+
+func (api *Client) dndRequest(ctx context.Context, path string, values url.Values) (*dndResponseFull, error) {
+	response := &dndResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// EndDND ends the user's scheduled Do Not Disturb session
+func (api *Client) EndDND() error {
+	return api.EndDNDContext(context.Background())
+}
+
+// EndDNDContext ends the user's scheduled Do Not Disturb session with a custom context
+func (api *Client) EndDNDContext(ctx context.Context) error {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	response := &SlackResponse{}
+
+	if err := api.postMethod(ctx, "dnd.endDnd", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// EndSnooze ends the current user's snooze mode
+func (api *Client) EndSnooze() (*DNDStatus, error) {
+	return api.EndSnoozeContext(context.Background())
+}
+
+// EndSnoozeContext ends the current user's snooze mode with a custom context
+func (api *Client) EndSnoozeContext(ctx context.Context) (*DNDStatus, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	response, err := api.dndRequest(ctx, "dnd.endSnooze", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.DNDStatus, nil
+}
+
+// GetDNDInfo provides information about a user's current Do Not Disturb settings.
+func (api *Client) GetDNDInfo(user *string) (*DNDStatus, error) {
+	return api.GetDNDInfoContext(context.Background(), user)
+}
+
+// GetDNDInfoContext provides information about a user's current Do Not Disturb settings with a custom context.
+func (api *Client) GetDNDInfoContext(ctx context.Context, user *string) (*DNDStatus, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if user != nil {
+		values.Set("user", *user)
+	}
+
+	response, err := api.dndRequest(ctx, "dnd.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.DNDStatus, nil
+}
+
+// GetDNDTeamInfo provides information about a user's current Do Not Disturb settings.
+func (api *Client) GetDNDTeamInfo(users []string) (map[string]DNDStatus, error) {
+	return api.GetDNDTeamInfoContext(context.Background(), users)
+}
+
+// GetDNDTeamInfoContext provides information about a user's current Do Not Disturb settings with a custom context.
+func (api *Client) GetDNDTeamInfoContext(ctx context.Context, users []string) (map[string]DNDStatus, error) {
+	values := url.Values{
+		"token": {api.token},
+		"users": {strings.Join(users, ",")},
+	}
+	response := &dndTeamInfoResponse{}
+
+	if err := api.postMethod(ctx, "dnd.teamInfo", values, response); err != nil {
+		return nil, err
+	}
+
+	if response.Err() != nil {
+		return nil, response.Err()
+	}
+
+	return response.Users, nil
+}
+
+// SetSnooze adjusts the snooze duration for a user's Do Not Disturb
+// settings. If a snooze session is not already active for the user, invoking
+// this method will begin one for the specified duration.
+func (api *Client) SetSnooze(minutes int) (*DNDStatus, error) {
+	return api.SetSnoozeContext(context.Background(), minutes)
+}
+
+// SetSnoozeContext adjusts the snooze duration for a user's Do Not Disturb settings with a custom context.
+// For more information see the SetSnooze docs
+func (api *Client) SetSnoozeContext(ctx context.Context, minutes int) (*DNDStatus, error) {
+	values := url.Values{
+		"token":       {api.token},
+		"num_minutes": {strconv.Itoa(minutes)},
+	}
+
+	response, err := api.dndRequest(ctx, "dnd.setSnooze", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.DNDStatus, nil
+}

backend/vendor/github.com/slack-go/slack/emoji.go

@@ -0,0 +1,35 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+type emojiResponseFull struct {
+	Emoji map[string]string `json:"emoji"`
+	SlackResponse
+}
+
+// GetEmoji retrieves all the emojis
+func (api *Client) GetEmoji() (map[string]string, error) {
+	return api.GetEmojiContext(context.Background())
+}
+
+// GetEmojiContext retrieves all the emojis with a custom context
+func (api *Client) GetEmojiContext(ctx context.Context) (map[string]string, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	response := &emojiResponseFull{}
+
+	err := api.postMethod(ctx, "emoji.list", values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	if response.Err() != nil {
+		return nil, response.Err()
+	}
+
+	return response.Emoji, nil
+}

backend/vendor/github.com/slack-go/slack/errors.go

@@ -0,0 +1,21 @@
+package slack
+
+import "github.com/slack-go/slack/internal/errorsx"
+
+// Errors returned by various methods.
+const (
+	ErrAlreadyDisconnected  = errorsx.String("Invalid call to Disconnect - Slack API is already disconnected")
+	ErrRTMDisconnected      = errorsx.String("disconnect received while trying to connect")
+	ErrRTMGoodbye           = errorsx.String("goodbye detected")
+	ErrRTMDeadman           = errorsx.String("deadman switch triggered")
+	ErrParametersMissing    = errorsx.String("received empty parameters")
+	ErrBlockIDNotUnique     = errorsx.String("Block ID needs to be unique")
+	ErrInvalidConfiguration = errorsx.String("invalid configuration")
+	ErrMissingHeaders       = errorsx.String("missing headers")
+	ErrExpiredTimestamp     = errorsx.String("timestamp is too old")
+)
+
+// internal errors
+const (
+	errPaginationComplete = errorsx.String("pagination complete")
+)

backend/vendor/github.com/slack-go/slack/files.go

@@ -0,0 +1,410 @@
+package slack
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+const (
+	// Add here the defaults in the siten
+	DEFAULT_FILES_USER        = ""
+	DEFAULT_FILES_CHANNEL     = ""
+	DEFAULT_FILES_TS_FROM     = 0
+	DEFAULT_FILES_TS_TO       = -1
+	DEFAULT_FILES_TYPES       = "all"
+	DEFAULT_FILES_COUNT       = 100
+	DEFAULT_FILES_PAGE        = 1
+	DEFAULT_FILES_SHOW_HIDDEN = false
+)
+
+// File contains all the information for a file
+type File struct {
+	ID        string   `json:"id"`
+	Created   JSONTime `json:"created"`
+	Timestamp JSONTime `json:"timestamp"`
+
+	Name              string `json:"name"`
+	Title             string `json:"title"`
+	Mimetype          string `json:"mimetype"`
+	ImageExifRotation int    `json:"image_exif_rotation"`
+	Filetype          string `json:"filetype"`
+	PrettyType        string `json:"pretty_type"`
+	User              string `json:"user"`
+
+	Mode         string `json:"mode"`
+	Editable     bool   `json:"editable"`
+	IsExternal   bool   `json:"is_external"`
+	ExternalType string `json:"external_type"`
+
+	Size int `json:"size"`
+
+	URL                string `json:"url"`          // Deprecated - never set
+	URLDownload        string `json:"url_download"` // Deprecated - never set
+	URLPrivate         string `json:"url_private"`
+	URLPrivateDownload string `json:"url_private_download"`
+
+	OriginalH   int    `json:"original_h"`
+	OriginalW   int    `json:"original_w"`
+	Thumb64     string `json:"thumb_64"`
+	Thumb80     string `json:"thumb_80"`
+	Thumb160    string `json:"thumb_160"`
+	Thumb360    string `json:"thumb_360"`
+	Thumb360Gif string `json:"thumb_360_gif"`
+	Thumb360W   int    `json:"thumb_360_w"`
+	Thumb360H   int    `json:"thumb_360_h"`
+	Thumb480    string `json:"thumb_480"`
+	Thumb480W   int    `json:"thumb_480_w"`
+	Thumb480H   int    `json:"thumb_480_h"`
+	Thumb720    string `json:"thumb_720"`
+	Thumb720W   int    `json:"thumb_720_w"`
+	Thumb720H   int    `json:"thumb_720_h"`
+	Thumb960    string `json:"thumb_960"`
+	Thumb960W   int    `json:"thumb_960_w"`
+	Thumb960H   int    `json:"thumb_960_h"`
+	Thumb1024   string `json:"thumb_1024"`
+	Thumb1024W  int    `json:"thumb_1024_w"`
+	Thumb1024H  int    `json:"thumb_1024_h"`
+
+	Permalink       string `json:"permalink"`
+	PermalinkPublic string `json:"permalink_public"`
+
+	EditLink         string `json:"edit_link"`
+	Preview          string `json:"preview"`
+	PreviewHighlight string `json:"preview_highlight"`
+	Lines            int    `json:"lines"`
+	LinesMore        int    `json:"lines_more"`
+
+	IsPublic        bool     `json:"is_public"`
+	PublicURLShared bool     `json:"public_url_shared"`
+	Channels        []string `json:"channels"`
+	Groups          []string `json:"groups"`
+	IMs             []string `json:"ims"`
+	InitialComment  Comment  `json:"initial_comment"`
+	CommentsCount   int      `json:"comments_count"`
+	NumStars        int      `json:"num_stars"`
+	IsStarred       bool     `json:"is_starred"`
+	Shares          Share    `json:"shares"`
+}
+
+type Share struct {
+	Public  map[string][]ShareFileInfo `json:"public"`
+	Private map[string][]ShareFileInfo `json:"private"`
+}
+
+type ShareFileInfo struct {
+	ReplyUsers      []string `json:"reply_users"`
+	ReplyUsersCount int      `json:"reply_users_count"`
+	ReplyCount      int      `json:"reply_count"`
+	Ts              string   `json:"ts"`
+	ThreadTs        string   `json:"thread_ts"`
+	LatestReply     string   `json:"latest_reply"`
+	ChannelName     string   `json:"channel_name"`
+	TeamID          string   `json:"team_id"`
+}
+
+// FileUploadParameters contains all the parameters necessary (including the optional ones) for an UploadFile() request.
+//
+// There are three ways to upload a file. You can either set Content if file is small, set Reader if file is large,
+// or provide a local file path in File to upload it from your filesystem.
+//
+// Note that when using the Reader option, you *must* specify the Filename, otherwise the Slack API isn't happy.
+type FileUploadParameters struct {
+	File            string
+	Content         string
+	Reader          io.Reader
+	Filetype        string
+	Filename        string
+	Title           string
+	InitialComment  string
+	Channels        []string
+	ThreadTimestamp string
+}
+
+// GetFilesParameters contains all the parameters necessary (including the optional ones) for a GetFiles() request
+type GetFilesParameters struct {
+	User          string
+	Channel       string
+	TimestampFrom JSONTime
+	TimestampTo   JSONTime
+	Types         string
+	Count         int
+	Page          int
+	ShowHidden    bool
+}
+
+// ListFilesParameters contains all the parameters necessary (including the optional ones) for a ListFiles() request
+type ListFilesParameters struct {
+	Limit   int
+	User    string
+	Channel string
+	Types   string
+	Cursor  string
+}
+
+type fileResponseFull struct {
+	File     `json:"file"`
+	Paging   `json:"paging"`
+	Comments []Comment        `json:"comments"`
+	Files    []File           `json:"files"`
+	Metadata ResponseMetadata `json:"response_metadata"`
+
+	SlackResponse
+}
+
+// NewGetFilesParameters provides an instance of GetFilesParameters with all the sane default values set
+func NewGetFilesParameters() GetFilesParameters {
+	return GetFilesParameters{
+		User:          DEFAULT_FILES_USER,
+		Channel:       DEFAULT_FILES_CHANNEL,
+		TimestampFrom: DEFAULT_FILES_TS_FROM,
+		TimestampTo:   DEFAULT_FILES_TS_TO,
+		Types:         DEFAULT_FILES_TYPES,
+		Count:         DEFAULT_FILES_COUNT,
+		Page:          DEFAULT_FILES_PAGE,
+		ShowHidden:    DEFAULT_FILES_SHOW_HIDDEN,
+	}
+}
+
+func (api *Client) fileRequest(ctx context.Context, path string, values url.Values) (*fileResponseFull, error) {
+	response := &fileResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// GetFileInfo retrieves a file and related comments
+func (api *Client) GetFileInfo(fileID string, count, page int) (*File, []Comment, *Paging, error) {
+	return api.GetFileInfoContext(context.Background(), fileID, count, page)
+}
+
+// GetFileInfoContext retrieves a file and related comments with a custom context
+func (api *Client) GetFileInfoContext(ctx context.Context, fileID string, count, page int) (*File, []Comment, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+		"count": {strconv.Itoa(count)},
+		"page":  {strconv.Itoa(page)},
+	}
+
+	response, err := api.fileRequest(ctx, "files.info", values)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return &response.File, response.Comments, &response.Paging, nil
+}
+
+// GetFile retreives a given file from its private download URL
+func (api *Client) GetFile(downloadURL string, writer io.Writer) error {
+	return downloadFile(api.httpclient, api.token, downloadURL, writer, api)
+}
+
+// GetFiles retrieves all files according to the parameters given
+func (api *Client) GetFiles(params GetFilesParameters) ([]File, *Paging, error) {
+	return api.GetFilesContext(context.Background(), params)
+}
+
+// ListFiles retrieves all files according to the parameters given. Uses cursor based pagination.
+func (api *Client) ListFiles(params ListFilesParameters) ([]File, *ListFilesParameters, error) {
+	return api.ListFilesContext(context.Background(), params)
+}
+
+// ListFilesContext retrieves all files according to the parameters given with a custom context. Uses cursor based pagination.
+func (api *Client) ListFilesContext(ctx context.Context, params ListFilesParameters) ([]File, *ListFilesParameters, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	if params.User != DEFAULT_FILES_USER {
+		values.Add("user", params.User)
+	}
+	if params.Channel != DEFAULT_FILES_CHANNEL {
+		values.Add("channel", params.Channel)
+	}
+	if params.Limit != DEFAULT_FILES_COUNT {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+
+	response, err := api.fileRequest(ctx, "files.list", values)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	params.Cursor = response.Metadata.Cursor
+
+	return response.Files, &params, nil
+}
+
+// GetFilesContext retrieves all files according to the parameters given with a custom context
+func (api *Client) GetFilesContext(ctx context.Context, params GetFilesParameters) ([]File, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.User != DEFAULT_FILES_USER {
+		values.Add("user", params.User)
+	}
+	if params.Channel != DEFAULT_FILES_CHANNEL {
+		values.Add("channel", params.Channel)
+	}
+	if params.TimestampFrom != DEFAULT_FILES_TS_FROM {
+		values.Add("ts_from", strconv.FormatInt(int64(params.TimestampFrom), 10))
+	}
+	if params.TimestampTo != DEFAULT_FILES_TS_TO {
+		values.Add("ts_to", strconv.FormatInt(int64(params.TimestampTo), 10))
+	}
+	if params.Types != DEFAULT_FILES_TYPES {
+		values.Add("types", params.Types)
+	}
+	if params.Count != DEFAULT_FILES_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_FILES_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+	if params.ShowHidden != DEFAULT_FILES_SHOW_HIDDEN {
+		values.Add("show_files_hidden_by_limit", strconv.FormatBool(params.ShowHidden))
+	}
+
+	response, err := api.fileRequest(ctx, "files.list", values)
+	if err != nil {
+		return nil, nil, err
+	}
+	return response.Files, &response.Paging, nil
+}
+
+// UploadFile uploads a file
+func (api *Client) UploadFile(params FileUploadParameters) (file *File, err error) {
+	return api.UploadFileContext(context.Background(), params)
+}
+
+// UploadFileContext uploads a file and setting a custom context
+func (api *Client) UploadFileContext(ctx context.Context, params FileUploadParameters) (file *File, err error) {
+	// Test if user token is valid. This helps because client.Do doesn't like this for some reason. XXX: More
+	// investigation needed, but for now this will do.
+	_, err = api.AuthTest()
+	if err != nil {
+		return nil, err
+	}
+	response := &fileResponseFull{}
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.Filetype != "" {
+		values.Add("filetype", params.Filetype)
+	}
+	if params.Filename != "" {
+		values.Add("filename", params.Filename)
+	}
+	if params.Title != "" {
+		values.Add("title", params.Title)
+	}
+	if params.InitialComment != "" {
+		values.Add("initial_comment", params.InitialComment)
+	}
+	if params.ThreadTimestamp != "" {
+		values.Add("thread_ts", params.ThreadTimestamp)
+	}
+	if len(params.Channels) != 0 {
+		values.Add("channels", strings.Join(params.Channels, ","))
+	}
+	if params.Content != "" {
+		values.Add("content", params.Content)
+		err = api.postMethod(ctx, "files.upload", values, response)
+	} else if params.File != "" {
+		err = postLocalWithMultipartResponse(ctx, api.httpclient, api.endpoint+"files.upload", params.File, "file", values, response, api)
+	} else if params.Reader != nil {
+		if params.Filename == "" {
+			return nil, fmt.Errorf("files.upload: FileUploadParameters.Filename is mandatory when using FileUploadParameters.Reader")
+		}
+		err = postWithMultipartResponse(ctx, api.httpclient, api.endpoint+"files.upload", params.Filename, "file", values, params.Reader, response, api)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	return &response.File, response.Err()
+}
+
+// DeleteFileComment deletes a file's comment
+func (api *Client) DeleteFileComment(commentID, fileID string) error {
+	return api.DeleteFileCommentContext(context.Background(), fileID, commentID)
+}
+
+// DeleteFileCommentContext deletes a file's comment with a custom context
+func (api *Client) DeleteFileCommentContext(ctx context.Context, fileID, commentID string) (err error) {
+	if fileID == "" || commentID == "" {
+		return ErrParametersMissing
+	}
+
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+		"id":    {commentID},
+	}
+	_, err = api.fileRequest(ctx, "files.comments.delete", values)
+	return err
+}
+
+// DeleteFile deletes a file
+func (api *Client) DeleteFile(fileID string) error {
+	return api.DeleteFileContext(context.Background(), fileID)
+}
+
+// DeleteFileContext deletes a file with a custom context
+func (api *Client) DeleteFileContext(ctx context.Context, fileID string) (err error) {
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+	}
+
+	_, err = api.fileRequest(ctx, "files.delete", values)
+	return err
+}
+
+// RevokeFilePublicURL disables public/external sharing for a file
+func (api *Client) RevokeFilePublicURL(fileID string) (*File, error) {
+	return api.RevokeFilePublicURLContext(context.Background(), fileID)
+}
+
+// RevokeFilePublicURLContext disables public/external sharing for a file with a custom context
+func (api *Client) RevokeFilePublicURLContext(ctx context.Context, fileID string) (*File, error) {
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+	}
+
+	response, err := api.fileRequest(ctx, "files.revokePublicURL", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.File, nil
+}
+
+// ShareFilePublicURL enabled public/external sharing for a file
+func (api *Client) ShareFilePublicURL(fileID string) (*File, []Comment, *Paging, error) {
+	return api.ShareFilePublicURLContext(context.Background(), fileID)
+}
+
+// ShareFilePublicURLContext enabled public/external sharing for a file with a custom context
+func (api *Client) ShareFilePublicURLContext(ctx context.Context, fileID string) (*File, []Comment, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+	}
+
+	response, err := api.fileRequest(ctx, "files.sharedPublicURL", values)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return &response.File, response.Comments, &response.Paging, nil
+}

backend/vendor/github.com/slack-go/slack/go.mod

@@ -0,0 +1,12 @@
+module github.com/slack-go/slack
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-test/deep v1.0.4
+	github.com/gorilla/websocket v1.4.2
+	github.com/pkg/errors v0.8.0
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.2.2
+)
+
+go 1.13

backend/vendor/github.com/slack-go/slack/go.sum

@@ -0,0 +1,12 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-test/deep v1.0.4 h1:u2CU3YKy9I2pmu9pX0eq50wCgjfGIt539SqR7FbHiho=
+github.com/go-test/deep v1.0.4/go.mod h1:wGDj63lr65AM2AQyKZd/NYHGb0R+1RLqB8NKt3aSFNA=
+github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
+github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
+github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=

backend/vendor/github.com/slack-go/slack/groups.go

@@ -0,0 +1,574 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+// Group contains all the information for a group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+type Group struct {
+	GroupConversation
+	IsGroup bool `json:"is_group"`
+}
+
+type groupResponseFull struct {
+	Group          Group   `json:"group"`
+	Groups         []Group `json:"groups"`
+	Purpose        string  `json:"purpose"`
+	Topic          string  `json:"topic"`
+	NotInGroup     bool    `json:"not_in_group"`
+	NoOp           bool    `json:"no_op"`
+	AlreadyClosed  bool    `json:"already_closed"`
+	AlreadyOpen    bool    `json:"already_open"`
+	AlreadyInGroup bool    `json:"already_in_group"`
+	Channel        Channel `json:"channel"`
+	History
+	SlackResponse
+}
+
+func (api *Client) groupRequest(ctx context.Context, path string, values url.Values) (*groupResponseFull, error) {
+	response := &groupResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// ArchiveGroup archives a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) ArchiveGroup(group string) error {
+	return api.ArchiveGroupContext(context.Background(), group)
+}
+
+// ArchiveGroupContext archives a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) ArchiveGroupContext(ctx context.Context, group string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	_, err := api.groupRequest(ctx, "groups.archive", values)
+	return err
+}
+
+// UnarchiveGroup unarchives a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) UnarchiveGroup(group string) error {
+	return api.UnarchiveGroupContext(context.Background(), group)
+}
+
+// UnarchiveGroupContext unarchives a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) UnarchiveGroupContext(ctx context.Context, group string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	_, err := api.groupRequest(ctx, "groups.unarchive", values)
+	return err
+}
+
+// CreateGroup creates a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) CreateGroup(group string) (*Group, error) {
+	return api.CreateGroupContext(context.Background(), group)
+}
+
+// CreateGroupContext creates a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) CreateGroupContext(ctx context.Context, group string) (*Group, error) {
+	values := url.Values{
+		"token": {api.token},
+		"name":  {group},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.create", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Group, nil
+}
+
+// CreateChildGroup creates a new private group archiving the old one
+// This method takes an existing private group and performs the following steps:
+//   1. Renames the existing group (from "example" to "example-archived").
+//   2. Archives the existing group.
+//   3. Creates a new group with the name of the existing group.
+//   4. Adds all members of the existing group to the new group.
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) CreateChildGroup(group string) (*Group, error) {
+	return api.CreateChildGroupContext(context.Background(), group)
+}
+
+// CreateChildGroupContext creates a new private group archiving the old one with a custom context
+// For more information see CreateChildGroup
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) CreateChildGroupContext(ctx context.Context, group string) (*Group, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.createChild", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Group, nil
+}
+
+// GetGroupHistory fetches all the history for a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetGroupHistory(group string, params HistoryParameters) (*History, error) {
+	return api.GetGroupHistoryContext(context.Background(), group, params)
+}
+
+// GetGroupHistoryContext fetches all the history for a private group with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetGroupHistoryContext(ctx context.Context, group string, params HistoryParameters) (*History, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+	if params.Latest != DEFAULT_HISTORY_LATEST {
+		values.Add("latest", params.Latest)
+	}
+	if params.Oldest != DEFAULT_HISTORY_OLDEST {
+		values.Add("oldest", params.Oldest)
+	}
+	if params.Count != DEFAULT_HISTORY_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Inclusive != DEFAULT_HISTORY_INCLUSIVE {
+		if params.Inclusive {
+			values.Add("inclusive", "1")
+		} else {
+			values.Add("inclusive", "0")
+		}
+	}
+	if params.Unreads != DEFAULT_HISTORY_UNREADS {
+		if params.Unreads {
+			values.Add("unreads", "1")
+		} else {
+			values.Add("unreads", "0")
+		}
+	}
+
+	response, err := api.groupRequest(ctx, "groups.history", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.History, nil
+}
+
+// InviteUserToGroup invites a specific user to a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) InviteUserToGroup(group, user string) (*Group, bool, error) {
+	return api.InviteUserToGroupContext(context.Background(), group, user)
+}
+
+// InviteUserToGroupContext invites a specific user to a private group with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) InviteUserToGroupContext(ctx context.Context, group, user string) (*Group, bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"user":    {user},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.invite", values)
+	if err != nil {
+		return nil, false, err
+	}
+	return &response.Group, response.AlreadyInGroup, nil
+}
+
+// LeaveGroup makes authenticated user leave the group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) LeaveGroup(group string) error {
+	return api.LeaveGroupContext(context.Background(), group)
+}
+
+// LeaveGroupContext makes authenticated user leave the group with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) LeaveGroupContext(ctx context.Context, group string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	_, err = api.groupRequest(ctx, "groups.leave", values)
+	return err
+}
+
+// KickUserFromGroup kicks a user from a group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) KickUserFromGroup(group, user string) error {
+	return api.KickUserFromGroupContext(context.Background(), group, user)
+}
+
+// KickUserFromGroupContext kicks a user from a group with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) KickUserFromGroupContext(ctx context.Context, group, user string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"user":    {user},
+	}
+
+	_, err = api.groupRequest(ctx, "groups.kick", values)
+	return err
+}
+
+// GetGroups retrieves all groups
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetGroups(excludeArchived bool) ([]Group, error) {
+	return api.GetGroupsContext(context.Background(), excludeArchived)
+}
+
+// GetGroupsContext retrieves all groups with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetGroupsContext(ctx context.Context, excludeArchived bool) ([]Group, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if excludeArchived {
+		values.Add("exclude_archived", "1")
+	}
+
+	response, err := api.groupRequest(ctx, "groups.list", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.Groups, nil
+}
+
+// GetGroupInfo retrieves the given group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetGroupInfo(group string) (*Group, error) {
+	return api.GetGroupInfoContext(context.Background(), group)
+}
+
+// GetGroupInfoContext retrieves the given group with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetGroupInfoContext(ctx context.Context, group string) (*Group, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"channel":        {group},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Group, nil
+}
+
+// SetGroupReadMark sets the read mark on a private group
+// Clients should try to avoid making this call too often. When needing to mark a read position, a client should set a
+// timer before making the call. In this way, any further updates needed during the timeout will not generate extra
+// calls (just one per channel). This is useful for when reading scroll-back history, or following a busy live
+// channel. A timeout of 5 seconds is a good starting point. Be sure to flush these calls on shutdown/logout.
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetGroupReadMark(group, ts string) error {
+	return api.SetGroupReadMarkContext(context.Background(), group, ts)
+}
+
+// SetGroupReadMarkContext sets the read mark on a private group with a custom context
+// For more details see SetGroupReadMark
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetGroupReadMarkContext(ctx context.Context, group, ts string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"ts":      {ts},
+	}
+
+	_, err = api.groupRequest(ctx, "groups.mark", values)
+	return err
+}
+
+// OpenGroup opens a private group
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) OpenGroup(group string) (bool, bool, error) {
+	return api.OpenGroupContext(context.Background(), group)
+}
+
+// OpenGroupContext opens a private group with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) OpenGroupContext(ctx context.Context, group string) (bool, bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.open", values)
+	if err != nil {
+		return false, false, err
+	}
+	return response.NoOp, response.AlreadyOpen, nil
+}
+
+// RenameGroup renames a group
+// XXX: They return a channel, not a group. What is this crap? :(
+// Inconsistent api it seems.
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) RenameGroup(group, name string) (*Channel, error) {
+	return api.RenameGroupContext(context.Background(), group, name)
+}
+
+// RenameGroupContext renames a group with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) RenameGroupContext(ctx context.Context, group, name string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"name":    {name},
+	}
+
+	// XXX: the created entry in this call returns a string instead of a number
+	// so I may have to do some workaround to solve it.
+	response, err := api.groupRequest(ctx, "groups.rename", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// SetGroupPurpose sets the group purpose
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetGroupPurpose(group, purpose string) (string, error) {
+	return api.SetGroupPurposeContext(context.Background(), group, purpose)
+}
+
+// SetGroupPurposeContext sets the group purpose with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetGroupPurposeContext(ctx context.Context, group, purpose string) (string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"purpose": {purpose},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.setPurpose", values)
+	if err != nil {
+		return "", err
+	}
+	return response.Purpose, nil
+}
+
+// SetGroupTopic sets the group topic
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetGroupTopic(group, topic string) (string, error) {
+	return api.SetGroupTopicContext(context.Background(), group, topic)
+}
+
+// SetGroupTopicContext sets the group topic with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) SetGroupTopicContext(ctx context.Context, group, topic string) (string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"topic":   {topic},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.setTopic", values)
+	if err != nil {
+		return "", err
+	}
+	return response.Topic, nil
+}
+
+// GetGroupReplies gets an entire thread (a message plus all the messages in reply to it).
+// see https://api.slack.com/methods/groups.replies
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetGroupReplies(channelID, thread_ts string) ([]Message, error) {
+	return api.GetGroupRepliesContext(context.Background(), channelID, thread_ts)
+}
+
+// GetGroupRepliesContext gets an entire thread (a message plus all the messages in reply to it) with a custom context
+// see https://api.slack.com/methods/groups.replies
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetGroupRepliesContext(ctx context.Context, channelID, thread_ts string) ([]Message, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"channel":   {channelID},
+		"thread_ts": {thread_ts},
+	}
+	response, err := api.groupRequest(ctx, "groups.replies", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.History.Messages, nil
+}

backend/vendor/github.com/slack-go/slack/history.go

@@ -0,0 +1,37 @@
+package slack
+
+const (
+	DEFAULT_HISTORY_LATEST    = ""
+	DEFAULT_HISTORY_OLDEST    = "0"
+	DEFAULT_HISTORY_COUNT     = 100
+	DEFAULT_HISTORY_INCLUSIVE = false
+	DEFAULT_HISTORY_UNREADS   = false
+)
+
+// HistoryParameters contains all the necessary information to help in the retrieval of history for Channels/Groups/DMs
+type HistoryParameters struct {
+	Latest    string
+	Oldest    string
+	Count     int
+	Inclusive bool
+	Unreads   bool
+}
+
+// History contains message history information needed to navigate a Channel / Group / DM history
+type History struct {
+	Latest   string    `json:"latest"`
+	Messages []Message `json:"messages"`
+	HasMore  bool      `json:"has_more"`
+	Unread   int       `json:"unread_count_display"`
+}
+
+// NewHistoryParameters provides an instance of HistoryParameters with all the sane default values set
+func NewHistoryParameters() HistoryParameters {
+	return HistoryParameters{
+		Latest:    DEFAULT_HISTORY_LATEST,
+		Oldest:    DEFAULT_HISTORY_OLDEST,
+		Count:     DEFAULT_HISTORY_COUNT,
+		Inclusive: DEFAULT_HISTORY_INCLUSIVE,
+		Unreads:   DEFAULT_HISTORY_UNREADS,
+	}
+}

backend/vendor/github.com/slack-go/slack/im.go

@@ -0,0 +1,220 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+type imChannel struct {
+	ID string `json:"id"`
+}
+
+type imResponseFull struct {
+	NoOp          bool      `json:"no_op"`
+	AlreadyClosed bool      `json:"already_closed"`
+	AlreadyOpen   bool      `json:"already_open"`
+	Channel       imChannel `json:"channel"`
+	IMs           []IM      `json:"ims"`
+	History
+	SlackResponse
+}
+
+// IM contains information related to the Direct Message channel
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+type IM struct {
+	Conversation
+	IsUserDeleted bool `json:"is_user_deleted"`
+}
+
+func (api *Client) imRequest(ctx context.Context, path string, values url.Values) (*imResponseFull, error) {
+	response := &imResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// CloseIMChannel closes the direct message channel
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) CloseIMChannel(channel string) (bool, bool, error) {
+	return api.CloseIMChannelContext(context.Background(), channel)
+}
+
+// CloseIMChannelContext closes the direct message channel with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) CloseIMChannelContext(ctx context.Context, channel string) (bool, bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channel},
+	}
+
+	response, err := api.imRequest(ctx, "im.close", values)
+	if err != nil {
+		return false, false, err
+	}
+	return response.NoOp, response.AlreadyClosed, nil
+}
+
+// OpenIMChannel opens a direct message channel to the user provided as argument
+// Returns some status and the channel ID
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) OpenIMChannel(user string) (bool, bool, string, error) {
+	return api.OpenIMChannelContext(context.Background(), user)
+}
+
+// OpenIMChannelContext opens a direct message channel to the user provided as argument with a custom context
+// Returns some status and the channel ID
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) OpenIMChannelContext(ctx context.Context, user string) (bool, bool, string, error) {
+	values := url.Values{
+		"token": {api.token},
+		"user":  {user},
+	}
+
+	response, err := api.imRequest(ctx, "im.open", values)
+	if err != nil {
+		return false, false, "", err
+	}
+	return response.NoOp, response.AlreadyOpen, response.Channel.ID, nil
+}
+
+// MarkIMChannel sets the read mark of a direct message channel to a specific point
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) MarkIMChannel(channel, ts string) (err error) {
+	return api.MarkIMChannelContext(context.Background(), channel, ts)
+}
+
+// MarkIMChannelContext sets the read mark of a direct message channel to a specific point with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) MarkIMChannelContext(ctx context.Context, channel, ts string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channel},
+		"ts":      {ts},
+	}
+
+	_, err := api.imRequest(ctx, "im.mark", values)
+	return err
+}
+
+// GetIMHistory retrieves the direct message channel history
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetIMHistory(channel string, params HistoryParameters) (*History, error) {
+	return api.GetIMHistoryContext(context.Background(), channel, params)
+}
+
+// GetIMHistoryContext retrieves the direct message channel history with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetIMHistoryContext(ctx context.Context, channel string, params HistoryParameters) (*History, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channel},
+	}
+	if params.Latest != DEFAULT_HISTORY_LATEST {
+		values.Add("latest", params.Latest)
+	}
+	if params.Oldest != DEFAULT_HISTORY_OLDEST {
+		values.Add("oldest", params.Oldest)
+	}
+	if params.Count != DEFAULT_HISTORY_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Inclusive != DEFAULT_HISTORY_INCLUSIVE {
+		if params.Inclusive {
+			values.Add("inclusive", "1")
+		} else {
+			values.Add("inclusive", "0")
+		}
+	}
+	if params.Unreads != DEFAULT_HISTORY_UNREADS {
+		if params.Unreads {
+			values.Add("unreads", "1")
+		} else {
+			values.Add("unreads", "0")
+		}
+	}
+
+	response, err := api.imRequest(ctx, "im.history", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.History, nil
+}
+
+// GetIMChannels returns the list of direct message channels
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetIMChannels() ([]IM, error) {
+	return api.GetIMChannelsContext(context.Background())
+}
+
+// GetIMChannelsContext returns the list of direct message channels with a custom context
+//
+// Deprecated: channels.*, groups.* im.* and mpim.* methods will be deprecated in the next version.
+// In Slack, these API are no longer available for  newly Apps created after June 10th, 2020.
+// Also, existing applications will not be able to use these APIs after February 24th, 2021.
+//
+// See also: https://api.slack.com/changelog/2020-01-deprecating-antecedents-to-the-conversations-api
+func (api *Client) GetIMChannelsContext(ctx context.Context) ([]IM, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	response, err := api.imRequest(ctx, "im.list", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.IMs, nil
+}

backend/vendor/github.com/slack-go/slack/info.go

@@ -0,0 +1,468 @@
+package slack
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type UserPrefsCarrier struct {
+	SlackResponse
+	UserPrefs *UserPrefs `json:"prefs"`
+}
+
+// UserPrefs carries a bunch of user settings including some unknown types
+type UserPrefs struct {
+	UserColors       string `json:"user_colors,omitempty"`
+	ColorNamesInList bool   `json:"color_names_in_list,omitempty"`
+	// Keyboard UnknownType `json:"keyboard"`
+	EmailAlerts                         string `json:"email_alerts,omitempty"`
+	EmailAlertsSleepUntil               int    `json:"email_alerts_sleep_until,omitempty"`
+	EmailTips                           bool   `json:"email_tips,omitempty"`
+	EmailWeekly                         bool   `json:"email_weekly,omitempty"`
+	EmailOffers                         bool   `json:"email_offers,omitempty"`
+	EmailResearch                       bool   `json:"email_research,omitempty"`
+	EmailDeveloper                      bool   `json:"email_developer,omitempty"`
+	WelcomeMessageHidden                bool   `json:"welcome_message_hidden,omitempty"`
+	SearchSort                          string `json:"search_sort,omitempty"`
+	SearchFileSort                      string `json:"search_file_sort,omitempty"`
+	SearchChannelSort                   string `json:"search_channel_sort,omitempty"`
+	SearchPeopleSort                    string `json:"search_people_sort,omitempty"`
+	ExpandInlineImages                  bool   `json:"expand_inline_images,omitempty"`
+	ExpandInternalInlineImages          bool   `json:"expand_internal_inline_images,omitempty"`
+	ExpandSnippets                      bool   `json:"expand_snippets,omitempty"`
+	PostsFormattingGuide                bool   `json:"posts_formatting_guide,omitempty"`
+	SeenWelcome2                        bool   `json:"seen_welcome_2,omitempty"`
+	SeenSSBPrompt                       bool   `json:"seen_ssb_prompt,omitempty"`
+	SpacesNewXpBannerDismissed          bool   `json:"spaces_new_xp_banner_dismissed,omitempty"`
+	SearchOnlyMyChannels                bool   `json:"search_only_my_channels,omitempty"`
+	SearchOnlyCurrentTeam               bool   `json:"search_only_current_team,omitempty"`
+	SearchHideMyChannels                bool   `json:"search_hide_my_channels,omitempty"`
+	SearchOnlyShowOnline                bool   `json:"search_only_show_online,omitempty"`
+	SearchHideDeactivatedUsers          bool   `json:"search_hide_deactivated_users,omitempty"`
+	EmojiMode                           string `json:"emoji_mode,omitempty"`
+	EmojiUse                            string `json:"emoji_use,omitempty"`
+	HasInvited                          bool   `json:"has_invited,omitempty"`
+	HasUploaded                         bool   `json:"has_uploaded,omitempty"`
+	HasCreatedChannel                   bool   `json:"has_created_channel,omitempty"`
+	HasSearched                         bool   `json:"has_searched,omitempty"`
+	SearchExcludeChannels               string `json:"search_exclude_channels,omitempty"`
+	MessagesTheme                       string `json:"messages_theme,omitempty"`
+	WebappSpellcheck                    bool   `json:"webapp_spellcheck,omitempty"`
+	NoJoinedOverlays                    bool   `json:"no_joined_overlays,omitempty"`
+	NoCreatedOverlays                   bool   `json:"no_created_overlays,omitempty"`
+	DropboxEnabled                      bool   `json:"dropbox_enabled,omitempty"`
+	SeenDomainInviteReminder            bool   `json:"seen_domain_invite_reminder,omitempty"`
+	SeenMemberInviteReminder            bool   `json:"seen_member_invite_reminder,omitempty"`
+	MuteSounds                          bool   `json:"mute_sounds,omitempty"`
+	ArrowHistory                        bool   `json:"arrow_history,omitempty"`
+	TabUIReturnSelects                  bool   `json:"tab_ui_return_selects,omitempty"`
+	ObeyInlineImgLimit                  bool   `json:"obey_inline_img_limit,omitempty"`
+	RequireAt                           bool   `json:"require_at,omitempty"`
+	SsbSpaceWindow                      string `json:"ssb_space_window,omitempty"`
+	MacSsbBounce                        string `json:"mac_ssb_bounce,omitempty"`
+	MacSsbBullet                        bool   `json:"mac_ssb_bullet,omitempty"`
+	ExpandNonMediaAttachments           bool   `json:"expand_non_media_attachments,omitempty"`
+	ShowTyping                          bool   `json:"show_typing,omitempty"`
+	PagekeysHandled                     bool   `json:"pagekeys_handled,omitempty"`
+	LastSnippetType                     string `json:"last_snippet_type,omitempty"`
+	DisplayRealNamesOverride            int    `json:"display_real_names_override,omitempty"`
+	DisplayDisplayNames                 bool   `json:"display_display_names,omitempty"`
+	Time24                              bool   `json:"time24,omitempty"`
+	EnterIsSpecialInTbt                 bool   `json:"enter_is_special_in_tbt,omitempty"`
+	MsgInputSendBtn                     bool   `json:"msg_input_send_btn,omitempty"`
+	MsgInputSendBtnAutoSet              bool   `json:"msg_input_send_btn_auto_set,omitempty"`
+	MsgInputStickyComposer              bool   `json:"msg_input_sticky_composer,omitempty"`
+	GraphicEmoticons                    bool   `json:"graphic_emoticons,omitempty"`
+	ConvertEmoticons                    bool   `json:"convert_emoticons,omitempty"`
+	SsEmojis                            bool   `json:"ss_emojis,omitempty"`
+	SeenOnboardingStart                 bool   `json:"seen_onboarding_start,omitempty"`
+	OnboardingCancelled                 bool   `json:"onboarding_cancelled,omitempty"`
+	SeenOnboardingSlackbotConversation  bool   `json:"seen_onboarding_slackbot_conversation,omitempty"`
+	SeenOnboardingChannels              bool   `json:"seen_onboarding_channels,omitempty"`
+	SeenOnboardingDirectMessages        bool   `json:"seen_onboarding_direct_messages,omitempty"`
+	SeenOnboardingInvites               bool   `json:"seen_onboarding_invites,omitempty"`
+	SeenOnboardingSearch                bool   `json:"seen_onboarding_search,omitempty"`
+	SeenOnboardingRecentMentions        bool   `json:"seen_onboarding_recent_mentions,omitempty"`
+	SeenOnboardingStarredItems          bool   `json:"seen_onboarding_starred_items,omitempty"`
+	SeenOnboardingPrivateGroups         bool   `json:"seen_onboarding_private_groups,omitempty"`
+	SeenOnboardingBanner                bool   `json:"seen_onboarding_banner,omitempty"`
+	OnboardingSlackbotConversationStep  int    `json:"onboarding_slackbot_conversation_step,omitempty"`
+	SetTzAutomatically                  bool   `json:"set_tz_automatically,omitempty"`
+	SuppressLinkWarning                 bool   `json:"suppress_link_warning,omitempty"`
+	DndEnabled                          bool   `json:"dnd_enabled,omitempty"`
+	DndStartHour                        string `json:"dnd_start_hour,omitempty"`
+	DndEndHour                          string `json:"dnd_end_hour,omitempty"`
+	DndBeforeMonday                     string `json:"dnd_before_monday,omitempty"`
+	DndAfterMonday                      string `json:"dnd_after_monday,omitempty"`
+	DndEnabledMonday                    string `json:"dnd_enabled_monday,omitempty"`
+	DndBeforeTuesday                    string `json:"dnd_before_tuesday,omitempty"`
+	DndAfterTuesday                     string `json:"dnd_after_tuesday,omitempty"`
+	DndEnabledTuesday                   string `json:"dnd_enabled_tuesday,omitempty"`
+	DndBeforeWednesday                  string `json:"dnd_before_wednesday,omitempty"`
+	DndAfterWednesday                   string `json:"dnd_after_wednesday,omitempty"`
+	DndEnabledWednesday                 string `json:"dnd_enabled_wednesday,omitempty"`
+	DndBeforeThursday                   string `json:"dnd_before_thursday,omitempty"`
+	DndAfterThursday                    string `json:"dnd_after_thursday,omitempty"`
+	DndEnabledThursday                  string `json:"dnd_enabled_thursday,omitempty"`
+	DndBeforeFriday                     string `json:"dnd_before_friday,omitempty"`
+	DndAfterFriday                      string `json:"dnd_after_friday,omitempty"`
+	DndEnabledFriday                    string `json:"dnd_enabled_friday,omitempty"`
+	DndBeforeSaturday                   string `json:"dnd_before_saturday,omitempty"`
+	DndAfterSaturday                    string `json:"dnd_after_saturday,omitempty"`
+	DndEnabledSaturday                  string `json:"dnd_enabled_saturday,omitempty"`
+	DndBeforeSunday                     string `json:"dnd_before_sunday,omitempty"`
+	DndAfterSunday                      string `json:"dnd_after_sunday,omitempty"`
+	DndEnabledSunday                    string `json:"dnd_enabled_sunday,omitempty"`
+	DndDays                             string `json:"dnd_days,omitempty"`
+	DndCustomNewBadgeSeen               bool   `json:"dnd_custom_new_badge_seen,omitempty"`
+	DndNotificationScheduleNewBadgeSeen bool   `json:"dnd_notification_schedule_new_badge_seen,omitempty"`
+	// UnreadCollapsedChannels      unknownType                  `json:"unread_collapsed_channels,omitempty"`
+	SidebarBehavior          string `json:"sidebar_behavior,omitempty"`
+	ChannelSort              string `json:"channel_sort,omitempty"`
+	SeparatePrivateChannels  bool   `json:"separate_private_channels,omitempty"`
+	SeparateSharedChannels   bool   `json:"separate_shared_channels,omitempty"`
+	SidebarTheme             string `json:"sidebar_theme,omitempty"`
+	SidebarThemeCustomValues string `json:"sidebar_theme_custom_values,omitempty"`
+	NoInvitesWidgetInSidebar bool   `json:"no_invites_widget_in_sidebar,omitempty"`
+	NoOmniboxInChannels      bool   `json:"no_omnibox_in_channels,omitempty"`
+
+	KKeyOmniboxAutoHideCount       int    `json:"k_key_omnibox_auto_hide_count,omitempty"`
+	ShowSidebarQuickswitcherButton bool   `json:"show_sidebar_quickswitcher_button,omitempty"`
+	EntOrgWideChannelsSidebar      bool   `json:"ent_org_wide_channels_sidebar,omitempty"`
+	MarkMsgsReadImmediately        bool   `json:"mark_msgs_read_immediately,omitempty"`
+	StartScrollAtOldest            bool   `json:"start_scroll_at_oldest,omitempty"`
+	SnippetEditorWrapLongLines     bool   `json:"snippet_editor_wrap_long_lines,omitempty"`
+	LsDisabled                     bool   `json:"ls_disabled,omitempty"`
+	FKeySearch                     bool   `json:"f_key_search,omitempty"`
+	KKeyOmnibox                    bool   `json:"k_key_omnibox,omitempty"`
+	PromptedForEmailDisabling      bool   `json:"prompted_for_email_disabling,omitempty"`
+	NoMacelectronBanner            bool   `json:"no_macelectron_banner,omitempty"`
+	NoMacssb1Banner                bool   `json:"no_macssb1_banner,omitempty"`
+	NoMacssb2Banner                bool   `json:"no_macssb2_banner,omitempty"`
+	NoWinssb1Banner                bool   `json:"no_winssb1_banner,omitempty"`
+	HideUserGroupInfoPane          bool   `json:"hide_user_group_info_pane,omitempty"`
+	MentionsExcludeAtUserGroups    bool   `json:"mentions_exclude_at_user_groups,omitempty"`
+	MentionsExcludeReactions       bool   `json:"mentions_exclude_reactions,omitempty"`
+	PrivacyPolicySeen              bool   `json:"privacy_policy_seen,omitempty"`
+	EnterpriseMigrationSeen        bool   `json:"enterprise_migration_seen,omitempty"`
+	LastTosAcknowledged            string `json:"last_tos_acknowledged,omitempty"`
+	SearchExcludeBots              bool   `json:"search_exclude_bots,omitempty"`
+	LoadLato2                      bool   `json:"load_lato_2,omitempty"`
+	FullerTimestamps               bool   `json:"fuller_timestamps,omitempty"`
+	LastSeenAtChannelWarning       int    `json:"last_seen_at_channel_warning,omitempty"`
+	EmojiAutocompleteBig           bool   `json:"emoji_autocomplete_big,omitempty"`
+	TwoFactorAuthEnabled           bool   `json:"two_factor_auth_enabled,omitempty"`
+	// TwoFactorType                         unknownType    `json:"two_factor_type,omitempty"`
+	// TwoFactorBackupType                   unknownType    `json:"two_factor_backup_type,omitempty"`
+	HideHexSwatch          bool   `json:"hide_hex_swatch,omitempty"`
+	ShowJumperScores       bool   `json:"show_jumper_scores,omitempty"`
+	EnterpriseMdmCustomMsg string `json:"enterprise_mdm_custom_msg,omitempty"`
+	// EnterpriseExcludedAppTeams                 unknownType    `json:"enterprise_excluded_app_teams,omitempty"`
+	ClientLogsPri             string `json:"client_logs_pri,omitempty"`
+	FlannelServerPool         string `json:"flannel_server_pool,omitempty"`
+	MentionsExcludeAtChannels bool   `json:"mentions_exclude_at_channels,omitempty"`
+	ConfirmClearAllUnreads    bool   `json:"confirm_clear_all_unreads,omitempty"`
+	ConfirmUserMarkedAway     bool   `json:"confirm_user_marked_away,omitempty"`
+	BoxEnabled                bool   `json:"box_enabled,omitempty"`
+	SeenSingleEmojiMsg        bool   `json:"seen_single_emoji_msg,omitempty"`
+	ConfirmShCallStart        bool   `json:"confirm_sh_call_start,omitempty"`
+	PreferredSkinTone         string `json:"preferred_skin_tone,omitempty"`
+	ShowAllSkinTones          bool   `json:"show_all_skin_tones,omitempty"`
+	WhatsNewRead              int    `json:"whats_new_read,omitempty"`
+	// FrecencyJumper                           unknownType      `json:"frecency_jumper,omitempty"`
+	FrecencyEntJumper                       string `json:"frecency_ent_jumper,omitempty"`
+	FrecencyEntJumperBackup                 string `json:"frecency_ent_jumper_backup,omitempty"`
+	Jumbomoji                               bool   `json:"jumbomoji,omitempty"`
+	NewxpSeenLastMessage                    int    `json:"newxp_seen_last_message,omitempty"`
+	ShowMemoryInstrument                    bool   `json:"show_memory_instrument,omitempty"`
+	EnableUnreadView                        bool   `json:"enable_unread_view,omitempty"`
+	SeenUnreadViewCoachmark                 bool   `json:"seen_unread_view_coachmark,omitempty"`
+	EnableReactEmojiPicker                  bool   `json:"enable_react_emoji_picker,omitempty"`
+	SeenCustomStatusBadge                   bool   `json:"seen_custom_status_badge,omitempty"`
+	SeenCustomStatusCallout                 bool   `json:"seen_custom_status_callout,omitempty"`
+	SeenCustomStatusExpirationBadge         bool   `json:"seen_custom_status_expiration_badge,omitempty"`
+	UsedCustomStatusKbShortcut              bool   `json:"used_custom_status_kb_shortcut,omitempty"`
+	SeenGuestAdminSlackbotAnnouncement      bool   `json:"seen_guest_admin_slackbot_announcement,omitempty"`
+	SeenThreadsNotificationBanner           bool   `json:"seen_threads_notification_banner,omitempty"`
+	SeenNameTaggingCoachmark                bool   `json:"seen_name_tagging_coachmark,omitempty"`
+	AllUnreadsSortOrder                     string `json:"all_unreads_sort_order,omitempty"`
+	Locale                                  string `json:"locale,omitempty"`
+	SeenIntlChannelNamesCoachmark           bool   `json:"seen_intl_channel_names_coachmark,omitempty"`
+	SeenP2LocaleChangeMessage               int    `json:"seen_p2_locale_change_message,omitempty"`
+	SeenLocaleChangeMessage                 int    `json:"seen_locale_change_message,omitempty"`
+	SeenJapaneseLocaleChangeMessage         bool   `json:"seen_japanese_locale_change_message,omitempty"`
+	SeenSharedChannelsCoachmark             bool   `json:"seen_shared_channels_coachmark,omitempty"`
+	SeenSharedChannelsOptInChangeMessage    bool   `json:"seen_shared_channels_opt_in_change_message,omitempty"`
+	HasRecentlySharedaChannel               bool   `json:"has_recently_shared_a_channel,omitempty"`
+	SeenChannelBrowserAdminCoachmark        bool   `json:"seen_channel_browser_admin_coachmark,omitempty"`
+	SeenAdministrationMenu                  bool   `json:"seen_administration_menu,omitempty"`
+	SeenDraftsSectionCoachmark              bool   `json:"seen_drafts_section_coachmark,omitempty"`
+	SeenEmojiUpdateOverlayCoachmark         bool   `json:"seen_emoji_update_overlay_coachmark,omitempty"`
+	SeenSonicDeluxeToast                    int    `json:"seen_sonic_deluxe_toast,omitempty"`
+	SeenWysiwygDeluxeToast                  bool   `json:"seen_wysiwyg_deluxe_toast,omitempty"`
+	SeenMarkdownPasteToast                  int    `json:"seen_markdown_paste_toast,omitempty"`
+	SeenMarkdownPasteShortcut               int    `json:"seen_markdown_paste_shortcut,omitempty"`
+	SeenIaEducation                         bool   `json:"seen_ia_education,omitempty"`
+	PlainTextMode                           bool   `json:"plain_text_mode,omitempty"`
+	ShowSharedChannelsEducationBanner       bool   `json:"show_shared_channels_education_banner,omitempty"`
+	AllowCallsToSetCurrentStatus            bool   `json:"allow_calls_to_set_current_status,omitempty"`
+	InInteractiveMasMigrationFlow           bool   `json:"in_interactive_mas_migration_flow,omitempty"`
+	SunsetInteractiveMessageViews           int    `json:"sunset_interactive_message_views,omitempty"`
+	ShdepPromoCodeSubmitted                 bool   `json:"shdep_promo_code_submitted,omitempty"`
+	SeenShdepSlackbotMessage                bool   `json:"seen_shdep_slackbot_message,omitempty"`
+	SeenCallsInteractiveCoachmark           bool   `json:"seen_calls_interactive_coachmark,omitempty"`
+	AllowCmdTabIss                          bool   `json:"allow_cmd_tab_iss,omitempty"`
+	SeenWorkflowBuilderDeluxeToast          bool   `json:"seen_workflow_builder_deluxe_toast,omitempty"`
+	WorkflowBuilderIntroModalClickedThrough bool   `json:"workflow_builder_intro_modal_clicked_through,omitempty"`
+	// WorkflowBuilderCoachmarks                    unknownType  `json:"workflow_builder_coachmarks,omitempty"`
+	SeenGdriveCoachmark                            bool   `json:"seen_gdrive_coachmark,omitempty"`
+	OverloadedMessageEnabled                       bool   `json:"overloaded_message_enabled,omitempty"`
+	SeenHighlightsCoachmark                        bool   `json:"seen_highlights_coachmark,omitempty"`
+	SeenHighlightsArrowsCoachmark                  bool   `json:"seen_highlights_arrows_coachmark,omitempty"`
+	SeenHighlightsWarmWelcome                      bool   `json:"seen_highlights_warm_welcome,omitempty"`
+	SeenNewSearchUi                                bool   `json:"seen_new_search_ui,omitempty"`
+	SeenChannelSearch                              bool   `json:"seen_channel_search,omitempty"`
+	SeenPeopleSearch                               bool   `json:"seen_people_search,omitempty"`
+	SeenPeopleSearchCount                          int    `json:"seen_people_search_count,omitempty"`
+	DismissedScrollSearchTooltipCount              int    `json:"dismissed_scroll_search_tooltip_count,omitempty"`
+	LastDismissedScrollSearchTooltipTimestamp      int    `json:"last_dismissed_scroll_search_tooltip_timestamp,omitempty"`
+	HasUsedQuickswitcherShortcut                   bool   `json:"has_used_quickswitcher_shortcut,omitempty"`
+	SeenQuickswitcherShortcutTipCount              int    `json:"seen_quickswitcher_shortcut_tip_count,omitempty"`
+	BrowsersDismissedChannelsLowResultsEducation   bool   `json:"browsers_dismissed_channels_low_results_education,omitempty"`
+	BrowsersSeenInitialChannelsEducation           bool   `json:"browsers_seen_initial_channels_education,omitempty"`
+	BrowsersDismissedPeopleLowResultsEducation     bool   `json:"browsers_dismissed_people_low_results_education,omitempty"`
+	BrowsersSeenInitialPeopleEducation             bool   `json:"browsers_seen_initial_people_education,omitempty"`
+	BrowsersDismissedUserGroupsLowResultsEducation bool   `json:"browsers_dismissed_user_groups_low_results_education,omitempty"`
+	BrowsersSeenInitialUserGroupsEducation         bool   `json:"browsers_seen_initial_user_groups_education,omitempty"`
+	BrowsersDismissedFilesLowResultsEducation      bool   `json:"browsers_dismissed_files_low_results_education,omitempty"`
+	BrowsersSeenInitialFilesEducation              bool   `json:"browsers_seen_initial_files_education,omitempty"`
+	A11yAnimations                                 bool   `json:"a11y_animations,omitempty"`
+	SeenKeyboardShortcutsCoachmark                 bool   `json:"seen_keyboard_shortcuts_coachmark,omitempty"`
+	NeedsInitialPasswordSet                        bool   `json:"needs_initial_password_set,omitempty"`
+	LessonsEnabled                                 bool   `json:"lessons_enabled,omitempty"`
+	TractorEnabled                                 bool   `json:"tractor_enabled,omitempty"`
+	TractorExperimentGroup                         string `json:"tractor_experiment_group,omitempty"`
+	OpenedSlackbotDm                               bool   `json:"opened_slackbot_dm,omitempty"`
+	NewxpSuggestedChannels                         string `json:"newxp_suggested_channels,omitempty"`
+	OnboardingComplete                             bool   `json:"onboarding_complete,omitempty"`
+	WelcomePlaceState                              string `json:"welcome_place_state,omitempty"`
+	// OnboardingRoleApps  unknownType `json:"onboarding_role_apps,omitempty"`
+	HasReceivedThreadedMessage        bool   `json:"has_received_threaded_message,omitempty"`
+	SendYourFirstMessageBannerEnabled bool   `json:"send_your_first_message_banner_enabled,omitempty"`
+	WhocanseethisDmMpdmBadge          bool   `json:"whocanseethis_dm_mpdm_badge,omitempty"`
+	HighlightWords                    string `json:"highlight_words,omitempty"`
+	ThreadsEverything                 bool   `json:"threads_everything,omitempty"`
+	NoTextInNotifications             bool   `json:"no_text_in_notifications,omitempty"`
+	PushShowPreview                   bool   `json:"push_show_preview,omitempty"`
+	GrowlsEnabled                     bool   `json:"growls_enabled,omitempty"`
+	AllChannelsLoud                   bool   `json:"all_channels_loud,omitempty"`
+	PushDmAlert                       bool   `json:"push_dm_alert,omitempty"`
+	PushMentionAlert                  bool   `json:"push_mention_alert,omitempty"`
+	PushEverything                    bool   `json:"push_everything,omitempty"`
+	PushIdleWait                      int    `json:"push_idle_wait,omitempty"`
+	PushSound                         string `json:"push_sound,omitempty"`
+	NewMsgSnd                         string `json:"new_msg_snd,omitempty"`
+	PushLoudChannels                  string `json:"push_loud_channels,omitempty"`
+	PushMentionChannels               string `json:"push_mention_channels,omitempty"`
+	PushLoudChannelsSet               string `json:"push_loud_channels_set,omitempty"`
+	LoudChannels                      string `json:"loud_channels,omitempty"`
+	NeverChannels                     string `json:"never_channels,omitempty"`
+	LoudChannelsSet                   string `json:"loud_channels_set,omitempty"`
+	AtChannelSuppressedChannels       string `json:"at_channel_suppressed_channels,omitempty"`
+	PushAtChannelSuppressedChannels   string `json:"push_at_channel_suppressed_channels,omitempty"`
+	MutedChannels                     string `json:"muted_channels,omitempty"`
+	// AllNotificationsPrefs                  unknownType `json:"all_notifications_prefs,omitempty"`
+	GrowthMsgLimitApproachingCtaCount     int `json:"growth_msg_limit_approaching_cta_count,omitempty"`
+	GrowthMsgLimitApproachingCtaTs        int `json:"growth_msg_limit_approaching_cta_ts,omitempty"`
+	GrowthMsgLimitReachedCtaCount         int `json:"growth_msg_limit_reached_cta_count,omitempty"`
+	GrowthMsgLimitReachedCtaLastTs        int `json:"growth_msg_limit_reached_cta_last_ts,omitempty"`
+	GrowthMsgLimitLongReachedCtaCount     int `json:"growth_msg_limit_long_reached_cta_count,omitempty"`
+	GrowthMsgLimitLongReachedCtaLastTs    int `json:"growth_msg_limit_long_reached_cta_last_ts,omitempty"`
+	GrowthMsgLimitSixtyDayBannerCtaCount  int `json:"growth_msg_limit_sixty_day_banner_cta_count,omitempty"`
+	GrowthMsgLimitSixtyDayBannerCtaLastTs int `json:"growth_msg_limit_sixty_day_banner_cta_last_ts,omitempty"`
+	// GrowthAllBannersPrefs unknownType `json:"growth_all_banners_prefs,omitempty"`
+	AnalyticsUpsellCoachmarkSeen bool `json:"analytics_upsell_coachmark_seen,omitempty"`
+	SeenAppSpaceCoachmark        bool `json:"seen_app_space_coachmark,omitempty"`
+	SeenAppSpaceTutorial         bool `json:"seen_app_space_tutorial,omitempty"`
+	DismissedAppLauncherWelcome  bool `json:"dismissed_app_launcher_welcome,omitempty"`
+	DismissedAppLauncherLimit    bool `json:"dismissed_app_launcher_limit,omitempty"`
+	Purchaser                    bool `json:"purchaser,omitempty"`
+	ShowEntOnboarding            bool `json:"show_ent_onboarding,omitempty"`
+	FoldersEnabled               bool `json:"folders_enabled,omitempty"`
+	// FolderData unknownType `json:"folder_data,omitempty"`
+	SeenCorporateExportAlert               bool   `json:"seen_corporate_export_alert,omitempty"`
+	ShowAutocompleteHelp                   int    `json:"show_autocomplete_help,omitempty"`
+	DeprecationToastLastSeen               int    `json:"deprecation_toast_last_seen,omitempty"`
+	DeprecationModalLastSeen               int    `json:"deprecation_modal_last_seen,omitempty"`
+	Iap1Lab                                int    `json:"iap1_lab,omitempty"`
+	IaTopNavTheme                          string `json:"ia_top_nav_theme,omitempty"`
+	IaPlatformActionsLab                   int    `json:"ia_platform_actions_lab,omitempty"`
+	ActivityView                           string `json:"activity_view,omitempty"`
+	FailoverProxyCheckCompleted            int    `json:"failover_proxy_check_completed,omitempty"`
+	EdgeUploadProxyCheckCompleted          int    `json:"edge_upload_proxy_check_completed,omitempty"`
+	AppSubdomainCheckCompleted             int    `json:"app_subdomain_check_completed,omitempty"`
+	AddAppsPromptDismissed                 bool   `json:"add_apps_prompt_dismissed,omitempty"`
+	AddChannelPromptDismissed              bool   `json:"add_channel_prompt_dismissed,omitempty"`
+	ChannelSidebarHideInvite               bool   `json:"channel_sidebar_hide_invite,omitempty"`
+	InProdSurveysEnabled                   bool   `json:"in_prod_surveys_enabled,omitempty"`
+	DismissedInstalledAppDmSuggestions     string `json:"dismissed_installed_app_dm_suggestions,omitempty"`
+	SeenContextualMessageShortcutsModal    bool   `json:"seen_contextual_message_shortcuts_modal,omitempty"`
+	SeenMessageNavigationEducationalToast  bool   `json:"seen_message_navigation_educational_toast,omitempty"`
+	ContextualMessageShortcutsModalWasSeen bool   `json:"contextual_message_shortcuts_modal_was_seen,omitempty"`
+	MessageNavigationToastWasSeen          bool   `json:"message_navigation_toast_was_seen,omitempty"`
+	UpToBrowseKbShortcut                   bool   `json:"up_to_browse_kb_shortcut,omitempty"`
+	ChannelSections                        string `json:"channel_sections,omitempty"`
+	TZ                                     string `json:"tz,omitempty"`
+}
+
+func (api *Client) GetUserPrefs() (*UserPrefsCarrier, error) {
+	values := url.Values{"token": {api.token}}
+	response := UserPrefsCarrier{}
+
+	err := api.getMethod(context.Background(), "users.prefs.get", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response, response.Err()
+}
+
+func (api *Client) MuteChat(channelID string) (*UserPrefsCarrier, error) {
+	prefs, err := api.GetUserPrefs()
+	if err != nil {
+		return nil, err
+	}
+	chnls := strings.Split(prefs.UserPrefs.MutedChannels, ",")
+	for _, chn := range chnls {
+		if chn == channelID {
+			return nil, nil // noop
+		}
+	}
+	newChnls := prefs.UserPrefs.MutedChannels + "," + channelID
+	values := url.Values{"token": {api.token}, "muted_channels": {newChnls}, "reason": {"update-muted-channels"}}
+	response := UserPrefsCarrier{}
+
+	err = api.postMethod(context.Background(), "users.prefs.set", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response, response.Err()
+}
+
+func (api *Client) UnMuteChat(channelID string) (*UserPrefsCarrier, error) {
+	prefs, err := api.GetUserPrefs()
+	if err != nil {
+		return nil, err
+	}
+	chnls := strings.Split(prefs.UserPrefs.MutedChannels, ",")
+	newChnls := make([]string, len(chnls)-1)
+	for i, chn := range chnls {
+		if chn == channelID {
+			return nil, nil // noop
+		}
+		newChnls[i] = chn
+	}
+	values := url.Values{"token": {api.token}, "muted_channels": {strings.Join(newChnls, ",")}, "reason": {"update-muted-channels"}}
+	response := UserPrefsCarrier{}
+
+	err = api.postMethod(context.Background(), "users.prefs.set", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response, response.Err()
+}
+
+// UserDetails contains user details coming in the initial response from StartRTM
+type UserDetails struct {
+	ID             string    `json:"id"`
+	Name           string    `json:"name"`
+	Created        JSONTime  `json:"created"`
+	ManualPresence string    `json:"manual_presence"`
+	Prefs          UserPrefs `json:"prefs"`
+}
+
+// JSONTime exists so that we can have a String method converting the date
+type JSONTime int64
+
+// String converts the unix timestamp into a string
+func (t JSONTime) String() string {
+	tm := t.Time()
+	return fmt.Sprintf("\"%s\"", tm.Format("Mon Jan _2"))
+}
+
+// Time returns a `time.Time` representation of this value.
+func (t JSONTime) Time() time.Time {
+	return time.Unix(int64(t), 0)
+}
+
+// UnmarshalJSON will unmarshal both string and int JSON values
+func (t *JSONTime) UnmarshalJSON(buf []byte) error {
+	s := bytes.Trim(buf, `"`)
+
+	v, err := strconv.Atoi(string(s))
+	if err != nil {
+		return err
+	}
+
+	*t = JSONTime(int64(v))
+	return nil
+}
+
+// Team contains details about a team
+type Team struct {
+	ID     string `json:"id"`
+	Name   string `json:"name"`
+	Domain string `json:"domain"`
+}
+
+// Icons XXX: needs further investigation
+type Icons struct {
+	Image36 string `json:"image_36,omitempty"`
+	Image48 string `json:"image_48,omitempty"`
+	Image72 string `json:"image_72,omitempty"`
+}
+
+// Info contains various details about the authenticated user and team.
+// It is returned by StartRTM or included in the "ConnectedEvent" RTM event.
+type Info struct {
+	URL  string       `json:"url,omitempty"`
+	User *UserDetails `json:"self,omitempty"`
+	Team *Team        `json:"team,omitempty"`
+}
+
+type infoResponseFull struct {
+	Info
+	SlackResponse
+}
+
+// GetBotByID is deprecated and returns nil
+func (info Info) GetBotByID(botID string) *Bot {
+	return nil
+}
+
+// GetUserByID is deprecated and returns nil
+func (info Info) GetUserByID(userID string) *User {
+	return nil
+}
+
+// GetChannelByID is deprecated and returns nil
+func (info Info) GetChannelByID(channelID string) *Channel {
+	return nil
+}
+
+// GetGroupByID is deprecated and returns nil
+func (info Info) GetGroupByID(groupID string) *Group {
+	return nil
+}
+
+// GetIMByID is deprecated and returns nil
+func (info Info) GetIMByID(imID string) *IM {
+	return nil
+}

backend/vendor/github.com/slack-go/slack/interactions.go

@@ -0,0 +1,221 @@
+package slack
+
+import (
+	"bytes"
+	"encoding/json"
+)
+
+// InteractionType type of interactions
+type InteractionType string
+
+// ActionType type represents the type of action (attachment, block, etc.)
+type actionType string
+
+// action is an interface that should be implemented by all callback action types
+type action interface {
+	actionType() actionType
+}
+
+// Types of interactions that can be received.
+const (
+	InteractionTypeDialogCancellation = InteractionType("dialog_cancellation")
+	InteractionTypeDialogSubmission   = InteractionType("dialog_submission")
+	InteractionTypeDialogSuggestion   = InteractionType("dialog_suggestion")
+	InteractionTypeInteractionMessage = InteractionType("interactive_message")
+	InteractionTypeMessageAction      = InteractionType("message_action")
+	InteractionTypeBlockActions       = InteractionType("block_actions")
+	InteractionTypeBlockSuggestion    = InteractionType("block_suggestion")
+	InteractionTypeViewSubmission     = InteractionType("view_submission")
+	InteractionTypeViewClosed         = InteractionType("view_closed")
+	InteractionTypeShortcut           = InteractionType("shortcut")
+)
+
+// InteractionCallback is sent from slack when a user interactions with a button or dialog.
+type InteractionCallback struct {
+	Type            InteractionType `json:"type"`
+	Token           string          `json:"token"`
+	CallbackID      string          `json:"callback_id"`
+	ResponseURL     string          `json:"response_url"`
+	TriggerID       string          `json:"trigger_id"`
+	ActionTs        string          `json:"action_ts"`
+	Team            Team            `json:"team"`
+	Channel         Channel         `json:"channel"`
+	User            User            `json:"user"`
+	OriginalMessage Message         `json:"original_message"`
+	Message         Message         `json:"message"`
+	Name            string          `json:"name"`
+	Value           string          `json:"value"`
+	MessageTs       string          `json:"message_ts"`
+	AttachmentID    string          `json:"attachment_id"`
+	ActionCallback  ActionCallbacks `json:"actions"`
+	View            View            `json:"view"`
+	ActionID        string          `json:"action_id"`
+	APIAppID        string          `json:"api_app_id"`
+	BlockID         string          `json:"block_id"`
+	Container       Container       `json:"container"`
+	DialogSubmissionCallback
+	ViewSubmissionCallback
+	ViewClosedCallback
+
+	// FIXME(kanata2): just workaround for backward-compatibility.
+	// See also https://github.com/slack-go/slack/issues/816
+	RawState json.RawMessage `json:"state,omitempty"`
+
+	// BlockActionState stands for the `state` field in block_actions type.
+	// NOTE: InteractionCallback.State has a role for the state of dialog_submission type,
+	// so we cannot use this field for backward-compatibility for now.
+	BlockActionState *BlockActionStates `json:"-"`
+}
+
+type BlockActionStates struct {
+	Values map[string]map[string]BlockAction `json:"values"`
+}
+
+func (ic *InteractionCallback) MarshalJSON() ([]byte, error) {
+	type alias InteractionCallback
+	tmp := alias(*ic)
+	if tmp.Type == InteractionTypeBlockActions {
+		if tmp.BlockActionState == nil {
+			tmp.RawState = []byte(`{}`)
+		} else {
+			state, err := json.Marshal(tmp.BlockActionState.Values)
+			if err != nil {
+				return nil, err
+			}
+			tmp.RawState = []byte(`{"values":` + string(state) + `}`)
+		}
+	} else if ic.Type == InteractionTypeDialogSubmission {
+		tmp.RawState = []byte(tmp.State)
+	}
+	// Use pointer for go1.7
+	return json.Marshal(&tmp)
+}
+
+func (ic *InteractionCallback) UnmarshalJSON(b []byte) error {
+	type alias InteractionCallback
+	tmp := struct {
+		Type InteractionType `json:"type"`
+		*alias
+	}{
+		alias: (*alias)(ic),
+	}
+	if err := json.Unmarshal(b, &tmp); err != nil {
+		return err
+	}
+	*ic = InteractionCallback(*tmp.alias)
+	ic.Type = tmp.Type
+	if ic.Type == InteractionTypeBlockActions {
+		if len(ic.RawState) > 0 {
+			err := json.Unmarshal(ic.RawState, &ic.BlockActionState)
+			if err != nil {
+				return err
+			}
+		}
+	} else if ic.Type == InteractionTypeDialogSubmission {
+		ic.State = string(ic.RawState)
+	}
+	return nil
+}
+
+type Container struct {
+	Type         string      `json:"type"`
+	ViewID       string      `json:"view_id"`
+	MessageTs    string      `json:"message_ts"`
+	AttachmentID json.Number `json:"attachment_id"`
+	ChannelID    string      `json:"channel_id"`
+	IsEphemeral  bool        `json:"is_ephemeral"`
+	IsAppUnfurl  bool        `json:"is_app_unfurl"`
+}
+
+// ActionCallback is a convenience struct defined to allow dynamic unmarshalling of
+// the "actions" value in Slack's JSON response, which varies depending on block type
+type ActionCallbacks struct {
+	AttachmentActions []*AttachmentAction
+	BlockActions      []*BlockAction
+}
+
+// MarshalJSON implements the Marshaller interface in order to combine both
+// action callback types back into a single array, like how the api responds.
+// This makes Marshaling and Unmarshaling an InteractionCallback symmetrical
+func (a ActionCallbacks) MarshalJSON() ([]byte, error) {
+	count := 0
+	length := len(a.AttachmentActions) + len(a.BlockActions)
+	buffer := bytes.NewBufferString("[")
+
+	f := func(obj interface{}) error {
+		js, err := json.Marshal(obj)
+		if err != nil {
+			return err
+		}
+		_, err = buffer.Write(js)
+		if err != nil {
+			return err
+		}
+
+		count++
+		if count < length {
+			_, err = buffer.WriteString(",")
+			return err
+		}
+		return nil
+	}
+
+	for _, act := range a.AttachmentActions {
+		err := f(act)
+		if err != nil {
+			return nil, err
+		}
+	}
+	for _, blk := range a.BlockActions {
+		err := f(blk)
+		if err != nil {
+			return nil, err
+		}
+	}
+	buffer.WriteString("]")
+	return buffer.Bytes(), nil
+}
+
+// UnmarshalJSON implements the Marshaller interface in order to delegate
+// marshalling and allow for proper type assertion when decoding the response
+func (a *ActionCallbacks) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	for _, r := range raw {
+		var obj map[string]interface{}
+		err := json.Unmarshal(r, &obj)
+		if err != nil {
+			return err
+		}
+
+		if _, ok := obj["block_id"].(string); ok {
+			action, err := unmarshalAction(r, &BlockAction{})
+			if err != nil {
+				return err
+			}
+
+			a.BlockActions = append(a.BlockActions, action.(*BlockAction))
+			continue
+		}
+
+		action, err := unmarshalAction(r, &AttachmentAction{})
+		if err != nil {
+			return err
+		}
+		a.AttachmentActions = append(a.AttachmentActions, action.(*AttachmentAction))
+	}
+
+	return nil
+}
+
+func unmarshalAction(r json.RawMessage, callbackAction action) (action, error) {
+	err := json.Unmarshal(r, callbackAction)
+	if err != nil {
+		return nil, err
+	}
+	return callbackAction, nil
+}

backend/vendor/github.com/slack-go/slack/internal/backoff/backoff.go

@@ -0,0 +1,62 @@
+package backoff
+
+import (
+	"math/rand"
+	"time"
+)
+
+// This one was ripped from https://github.com/jpillora/backoff/blob/master/backoff.go
+
+// Backoff is a time.Duration counter. It starts at Min.  After every
+// call to Duration() it is multiplied by Factor.  It is capped at
+// Max. It returns to Min on every call to Reset().  Used in
+// conjunction with the time package.
+type Backoff struct {
+	attempts int
+	// Initial value to scale out
+	Initial time.Duration
+	// Jitter value randomizes an additional delay between 0 and Jitter
+	Jitter time.Duration
+	// Max maximum values of the backoff
+	Max time.Duration
+}
+
+// Returns the current value of the counter and then multiplies it
+// Factor
+func (b *Backoff) Duration() (dur time.Duration) {
+	// Zero-values are nonsensical, so we use
+	// them to apply defaults
+	if b.Max == 0 {
+		b.Max = 10 * time.Second
+	}
+
+	if b.Initial == 0 {
+		b.Initial = 100 * time.Millisecond
+	}
+
+	// calculate this duration
+	if dur = time.Duration(1 << uint(b.attempts)); dur > 0 {
+		dur = dur * b.Initial
+	} else {
+		dur = b.Max
+	}
+
+	if b.Jitter > 0 {
+		dur = dur + time.Duration(rand.Intn(int(b.Jitter)))
+	}
+
+	// bump attempts count
+	b.attempts++
+
+	return dur
+}
+
+//Resets the current value of the counter back to Min
+func (b *Backoff) Reset() {
+	b.attempts = 0
+}
+
+// Attempts returns the number of attempts that we had done so far
+func (b *Backoff) Attempts() int {
+	return b.attempts
+}

backend/vendor/github.com/slack-go/slack/internal/errorsx/errorsx.go

@@ -0,0 +1,17 @@
+package errorsx
+
+// String representing an error, useful for declaring string constants as errors.
+type String string
+
+func (t String) Error() string {
+	return string(t)
+}
+
+// Is reports whether String matches with the target error
+func (t String) Is(target error) bool {
+	if target == nil {
+		return false
+	}
+
+	return t.Error() == target.Error()
+}

backend/vendor/github.com/slack-go/slack/internal/misc/misc.go

@@ -0,0 +1,28 @@
+package misc
+
+import (
+	"fmt"
+	"net/http"
+)
+
+// StatusCodeError represents an http response error.
+// type httpStatusCode interface { HTTPStatusCode() int } to handle it.
+type StatusCodeError struct {
+	Code   int
+	Status string
+}
+
+func (t StatusCodeError) Error() string {
+	return fmt.Sprintf("slack server error: %s", t.Status)
+}
+
+func (t StatusCodeError) HTTPStatusCode() int {
+	return t.Code
+}
+
+func (t StatusCodeError) Retryable() bool {
+	if t.Code >= 500 || t.Code == http.StatusTooManyRequests {
+		return true
+	}
+	return false
+}

backend/vendor/github.com/slack-go/slack/internal/timex/timex.go

@@ -0,0 +1,18 @@
+package timex
+
+import "time"
+
+// Max returns the maximum duration
+func Max(values ...time.Duration) time.Duration {
+	var (
+		max time.Duration
+	)
+
+	for _, v := range values {
+		if v > max {
+			max = v
+		}
+	}
+
+	return max
+}

backend/vendor/github.com/slack-go/slack/item.go

@@ -0,0 +1,75 @@
+package slack
+
+const (
+	TYPE_MESSAGE      = "message"
+	TYPE_FILE         = "file"
+	TYPE_FILE_COMMENT = "file_comment"
+	TYPE_CHANNEL      = "channel"
+	TYPE_IM           = "im"
+	TYPE_GROUP        = "group"
+)
+
+// Item is any type of slack message - message, file, or file comment.
+type Item struct {
+	Type      string   `json:"type"`
+	Channel   string   `json:"channel,omitempty"`
+	Message   *Message `json:"message,omitempty"`
+	File      *File    `json:"file,omitempty"`
+	Comment   *Comment `json:"comment,omitempty"`
+	Timestamp string   `json:"ts,omitempty"`
+}
+
+// NewMessageItem turns a message on a channel into a typed message struct.
+func NewMessageItem(ch string, m *Message) Item {
+	return Item{Type: TYPE_MESSAGE, Channel: ch, Message: m}
+}
+
+// NewFileItem turns a file into a typed file struct.
+func NewFileItem(f *File) Item {
+	return Item{Type: TYPE_FILE, File: f}
+}
+
+// NewFileCommentItem turns a file and comment into a typed file_comment struct.
+func NewFileCommentItem(f *File, c *Comment) Item {
+	return Item{Type: TYPE_FILE_COMMENT, File: f, Comment: c}
+}
+
+// NewChannelItem turns a channel id into a typed channel struct.
+func NewChannelItem(ch string) Item {
+	return Item{Type: TYPE_CHANNEL, Channel: ch}
+}
+
+// NewIMItem turns a channel id into a typed im struct.
+func NewIMItem(ch string) Item {
+	return Item{Type: TYPE_IM, Channel: ch}
+}
+
+// NewGroupItem turns a channel id into a typed group struct.
+func NewGroupItem(ch string) Item {
+	return Item{Type: TYPE_GROUP, Channel: ch}
+}
+
+// ItemRef is a reference to a message of any type. One of FileID,
+// CommentId, or the combination of ChannelId and Timestamp must be
+// specified.
+type ItemRef struct {
+	Channel   string `json:"channel"`
+	Timestamp string `json:"timestamp"`
+	File      string `json:"file"`
+	Comment   string `json:"file_comment"`
+}
+
+// NewRefToMessage initializes a reference to to a message.
+func NewRefToMessage(channel, timestamp string) ItemRef {
+	return ItemRef{Channel: channel, Timestamp: timestamp}
+}
+
+// NewRefToFile initializes a reference to a file.
+func NewRefToFile(file string) ItemRef {
+	return ItemRef{File: file}
+}
+
+// NewRefToComment initializes a reference to a file comment.
+func NewRefToComment(comment string) ItemRef {
+	return ItemRef{Comment: comment}
+}

backend/vendor/github.com/slack-go/slack/logger.go

@@ -0,0 +1,60 @@
+package slack
+
+import (
+	"fmt"
+)
+
+// logger is a logger interface compatible with both stdlib and some
+// 3rd party loggers.
+type logger interface {
+	Output(int, string) error
+}
+
+// ilogger represents the internal logging api we use.
+type ilogger interface {
+	logger
+	Print(...interface{})
+	Printf(string, ...interface{})
+	Println(...interface{})
+}
+
+type Debug interface {
+	Debug() bool
+
+	// Debugf print a formatted debug line.
+	Debugf(format string, v ...interface{})
+	// Debugln print a debug line.
+	Debugln(v ...interface{})
+}
+
+// internalLog implements the additional methods used by our internal logging.
+type internalLog struct {
+	logger
+}
+
+// Println replicates the behaviour of the standard logger.
+func (t internalLog) Println(v ...interface{}) {
+	t.Output(2, fmt.Sprintln(v...))
+}
+
+// Printf replicates the behaviour of the standard logger.
+func (t internalLog) Printf(format string, v ...interface{}) {
+	t.Output(2, fmt.Sprintf(format, v...))
+}
+
+// Print replicates the behaviour of the standard logger.
+func (t internalLog) Print(v ...interface{}) {
+	t.Output(2, fmt.Sprint(v...))
+}
+
+type discard struct{}
+
+func (t discard) Debug() bool {
+	return false
+}
+
+// Debugf print a formatted debug line.
+func (t discard) Debugf(format string, v ...interface{}) {}
+
+// Debugln print a debug line.
+func (t discard) Debugln(v ...interface{}) {}

backend/vendor/github.com/slack-go/slack/messageID.go

@@ -0,0 +1,30 @@
+package slack
+
+import "sync"
+
+// IDGenerator provides an interface for generating integer ID values.
+type IDGenerator interface {
+	Next() int
+}
+
+// NewSafeID returns a new instance of an IDGenerator which is safe for
+// concurrent use by multiple goroutines.
+func NewSafeID(startID int) IDGenerator {
+	return &safeID{
+		nextID: startID,
+		mutex:  &sync.Mutex{},
+	}
+}
+
+type safeID struct {
+	nextID int
+	mutex  *sync.Mutex
+}
+
+func (s *safeID) Next() int {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	id := s.nextID
+	s.nextID++
+	return id
+}

backend/vendor/github.com/slack-go/slack/messages.go

@@ -0,0 +1,220 @@
+package slack
+
+// OutgoingMessage is used for the realtime API, and seems incomplete.
+type OutgoingMessage struct {
+	ID int `json:"id"`
+	// channel ID
+	Channel         string   `json:"channel,omitempty"`
+	Text            string   `json:"text,omitempty"`
+	Type            string   `json:"type,omitempty"`
+	ThreadTimestamp string   `json:"thread_ts,omitempty"`
+	ThreadBroadcast bool     `json:"reply_broadcast,omitempty"`
+	IDs             []string `json:"ids,omitempty"`
+}
+
+// Message is an auxiliary type to allow us to have a message containing sub messages
+type Message struct {
+	Msg
+	SubMessage      *Msg `json:"message,omitempty"`
+	PreviousMessage *Msg `json:"previous_message,omitempty"`
+}
+
+// Msg contains information about a slack message
+type Msg struct {
+	// Basic Message
+	ClientMsgID     string       `json:"client_msg_id,omitempty"`
+	Type            string       `json:"type,omitempty"`
+	Channel         string       `json:"channel,omitempty"`
+	User            string       `json:"user,omitempty"`
+	Text            string       `json:"text,omitempty"`
+	Timestamp       string       `json:"ts,omitempty"`
+	ThreadTimestamp string       `json:"thread_ts,omitempty"`
+	IsStarred       bool         `json:"is_starred,omitempty"`
+	PinnedTo        []string     `json:"pinned_to,omitempty"`
+	Attachments     []Attachment `json:"attachments,omitempty"`
+	Edited          *Edited      `json:"edited,omitempty"`
+	LastRead        string       `json:"last_read,omitempty"`
+	Subscribed      bool         `json:"subscribed,omitempty"`
+	UnreadCount     int          `json:"unread_count,omitempty"`
+
+	// Message Subtypes
+	SubType string `json:"subtype,omitempty"`
+
+	// Hidden Subtypes
+	Hidden           bool   `json:"hidden,omitempty"`     // message_changed, message_deleted, unpinned_item
+	DeletedTimestamp string `json:"deleted_ts,omitempty"` // message_deleted
+	EventTimestamp   string `json:"event_ts,omitempty"`
+
+	// bot_message (https://api.slack.com/events/message/bot_message)
+	BotID      string      `json:"bot_id,omitempty"`
+	Username   string      `json:"username,omitempty"`
+	Icons      *Icon       `json:"icons,omitempty"`
+	BotProfile *BotProfile `json:"bot_profile,omitempty"`
+
+	// channel_join, group_join
+	Inviter string `json:"inviter,omitempty"`
+
+	// channel_topic, group_topic
+	Topic string `json:"topic,omitempty"`
+
+	// channel_purpose, group_purpose
+	Purpose string `json:"purpose,omitempty"`
+
+	// channel_name, group_name
+	Name    string `json:"name,omitempty"`
+	OldName string `json:"old_name,omitempty"`
+
+	// channel_archive, group_archive
+	Members []string `json:"members,omitempty"`
+
+	// channels.replies, groups.replies, im.replies, mpim.replies
+	ReplyCount   int     `json:"reply_count,omitempty"`
+	Replies      []Reply `json:"replies,omitempty"`
+	ParentUserId string  `json:"parent_user_id,omitempty"`
+
+	// file_share, file_comment, file_mention
+	Files []File `json:"files,omitempty"`
+
+	// file_share
+	Upload bool `json:"upload,omitempty"`
+
+	// file_comment
+	Comment *Comment `json:"comment,omitempty"`
+
+	// pinned_item
+	ItemType string `json:"item_type,omitempty"`
+
+	// https://api.slack.com/rtm
+	ReplyTo int    `json:"reply_to,omitempty"`
+	Team    string `json:"team,omitempty"`
+
+	// reactions
+	Reactions []ItemReaction `json:"reactions,omitempty"`
+
+	// slash commands and interactive messages
+	ResponseType    string `json:"response_type,omitempty"`
+	ReplaceOriginal bool   `json:"replace_original"`
+	DeleteOriginal  bool   `json:"delete_original"`
+
+	// Block type Message
+	Blocks Blocks `json:"blocks,omitempty"`
+}
+
+const (
+	// ResponseTypeInChannel in channel response for slash commands.
+	ResponseTypeInChannel = "in_channel"
+	// ResponseTypeEphemeral ephemeral response for slash commands.
+	ResponseTypeEphemeral = "ephemeral"
+)
+
+// ScheduledMessage contains information about a slack scheduled message
+type ScheduledMessage struct {
+	ID          string `json:"id"`
+	Channel     string `json:"channel_id"`
+	PostAt      int    `json:"post_at"`
+	DateCreated int    `json:"date_created"`
+	Text        string `json:"text"`
+}
+
+// Icon is used for bot messages
+type Icon struct {
+	IconURL   string `json:"icon_url,omitempty"`
+	IconEmoji string `json:"icon_emoji,omitempty"`
+}
+
+// BotProfile contains information about a bot
+type BotProfile struct {
+	AppID   string `json:"app_id,omitempty"`
+	Deleted bool   `json:"deleted,omitempty"`
+	Icons   *Icons `json:"icons,omitempty"`
+	ID      string `json:"id,omitempty"`
+	Name    string `json:"name,omitempty"`
+	TeamID  string `json:"team_id,omitempty"`
+	Updated int64  `json:"updated,omitempty"`
+}
+
+// Edited indicates that a message has been edited.
+type Edited struct {
+	User      string `json:"user,omitempty"`
+	Timestamp string `json:"ts,omitempty"`
+}
+
+// Reply contains information about a reply for a thread
+type Reply struct {
+	User      string `json:"user,omitempty"`
+	Timestamp string `json:"ts,omitempty"`
+}
+
+// Event contains the event type
+type Event struct {
+	Type string `json:"type,omitempty"`
+}
+
+// Ping contains information about a Ping Event
+type Ping struct {
+	ID        int    `json:"id"`
+	Type      string `json:"type"`
+	Timestamp int64  `json:"timestamp"`
+}
+
+// Pong contains information about a Pong Event
+type Pong struct {
+	Type      string `json:"type"`
+	ReplyTo   int    `json:"reply_to"`
+	Timestamp int64  `json:"timestamp"`
+}
+
+// NewOutgoingMessage prepares an OutgoingMessage that the user can
+// use to send a message. Use this function to properly set the
+// messageID.
+func (rtm *RTM) NewOutgoingMessage(text string, channelID string, options ...RTMsgOption) *OutgoingMessage {
+	id := rtm.idGen.Next()
+	msg := OutgoingMessage{
+		ID:      id,
+		Type:    "message",
+		Channel: channelID,
+		Text:    text,
+	}
+	for _, option := range options {
+		option(&msg)
+	}
+	return &msg
+}
+
+// NewSubscribeUserPresence prepares an OutgoingMessage that the user can
+// use to subscribe presence events for the specified users.
+func (rtm *RTM) NewSubscribeUserPresence(ids []string) *OutgoingMessage {
+	return &OutgoingMessage{
+		Type: "presence_sub",
+		IDs:  ids,
+	}
+}
+
+// NewTypingMessage prepares an OutgoingMessage that the user can
+// use to send as a typing indicator. Use this function to properly set the
+// messageID.
+func (rtm *RTM) NewTypingMessage(channelID string) *OutgoingMessage {
+	id := rtm.idGen.Next()
+	return &OutgoingMessage{
+		ID:      id,
+		Type:    "typing",
+		Channel: channelID,
+	}
+}
+
+// RTMsgOption allows configuration of various options available for sending an RTM message
+type RTMsgOption func(*OutgoingMessage)
+
+// RTMsgOptionTS sets thead timestamp of an outgoing message in order to respond to a thread
+func RTMsgOptionTS(threadTimestamp string) RTMsgOption {
+	return func(msg *OutgoingMessage) {
+		msg.ThreadTimestamp = threadTimestamp
+	}
+}
+
+// RTMsgOptionBroadcast sets broadcast reply to channel to "true"
+func RTMsgOptionBroadcast() RTMsgOption {
+	return func(msg *OutgoingMessage) {
+		msg.ThreadBroadcast = true
+	}
+}

backend/vendor/github.com/slack-go/slack/misc.go

@@ -0,0 +1,341 @@
+package slack
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"mime"
+	"mime/multipart"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/slack-go/slack/internal/misc"
+)
+
+// SlackResponse handles parsing out errors from the web api.
+type SlackResponse struct {
+	Ok               bool             `json:"ok"`
+	Error            string           `json:"error"`
+	ResponseMetadata ResponseMetadata `json:"response_metadata"`
+}
+
+func (t SlackResponse) Err() error {
+	if t.Ok {
+		return nil
+	}
+
+	// handle pure text based responses like chat.post
+	// which while they have a slack response in their data structure
+	// it doesn't actually get set during parsing.
+	if strings.TrimSpace(t.Error) == "" {
+		return nil
+	}
+
+	return errors.New(t.Error)
+}
+
+// RateLimitedError represents the rate limit respond from slack
+type RateLimitedError struct {
+	RetryAfter time.Duration
+}
+
+func (e *RateLimitedError) Error() string {
+	return fmt.Sprintf("slack rate limit exceeded, retry after %s", e.RetryAfter)
+}
+
+func (e *RateLimitedError) Retryable() bool {
+	return true
+}
+
+func fileUploadReq(ctx context.Context, path string, values url.Values, r io.Reader) (*http.Request, error) {
+	req, err := http.NewRequest("POST", path, r)
+	if err != nil {
+		return nil, err
+	}
+
+	req = req.WithContext(ctx)
+	req.URL.RawQuery = (values).Encode()
+	return req, nil
+}
+
+func downloadFile(client httpClient, token string, downloadURL string, writer io.Writer, d Debug) error {
+	if downloadURL == "" {
+		return fmt.Errorf("received empty download URL")
+	}
+
+	req, err := http.NewRequest("GET", downloadURL, &bytes.Buffer{})
+	if err != nil {
+		return err
+	}
+
+	var bearer = "Bearer " + token
+	req.Header.Add("Authorization", bearer)
+	req.WithContext(context.Background())
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+
+	defer resp.Body.Close()
+
+	err = checkStatusCode(resp, d)
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(writer, resp.Body)
+
+	return err
+}
+
+func formReq(endpoint string, values url.Values) (req *http.Request, err error) {
+	if req, err = http.NewRequest("POST", endpoint, strings.NewReader(values.Encode())); err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	return req, nil
+}
+
+func jsonReq(endpoint string, body interface{}) (req *http.Request, err error) {
+	buffer := bytes.NewBuffer([]byte{})
+	if err = json.NewEncoder(buffer).Encode(body); err != nil {
+		return nil, err
+	}
+
+	if req, err = http.NewRequest("POST", endpoint, buffer); err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("Content-Type", "application/json; charset=utf-8")
+	return req, nil
+}
+
+func parseResponseBody(body io.ReadCloser, intf interface{}, d Debug) error {
+	response, err := ioutil.ReadAll(body)
+	if err != nil {
+		return err
+	}
+
+	if d.Debug() {
+		d.Debugln("parseResponseBody", string(response))
+	}
+
+	return json.Unmarshal(response, intf)
+}
+
+func postLocalWithMultipartResponse(ctx context.Context, client httpClient, method, fpath, fieldname string, values url.Values, intf interface{}, d Debug) error {
+	fullpath, err := filepath.Abs(fpath)
+	if err != nil {
+		return err
+	}
+	file, err := os.Open(fullpath)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	return postWithMultipartResponse(ctx, client, method, filepath.Base(fpath), fieldname, values, file, intf, d)
+}
+
+func postWithMultipartResponse(ctx context.Context, client httpClient, path, name, fieldname string, values url.Values, r io.Reader, intf interface{}, d Debug) error {
+	pipeReader, pipeWriter := io.Pipe()
+	wr := multipart.NewWriter(pipeWriter)
+	errc := make(chan error)
+	go func() {
+		defer pipeWriter.Close()
+		ioWriter, err := wr.CreateFormFile(fieldname, name)
+		if err != nil {
+			errc <- err
+			return
+		}
+		_, err = io.Copy(ioWriter, r)
+		if err != nil {
+			errc <- err
+			return
+		}
+		if err = wr.Close(); err != nil {
+			errc <- err
+			return
+		}
+	}()
+	req, err := fileUploadReq(ctx, path, values, pipeReader)
+	if err != nil {
+		return err
+	}
+	req.Header.Add("Content-Type", wr.FormDataContentType())
+	req = req.WithContext(ctx)
+	resp, err := client.Do(req)
+
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	err = checkStatusCode(resp, d)
+	if err != nil {
+		return err
+	}
+
+	select {
+	case err = <-errc:
+		return err
+	default:
+		return newJSONParser(intf)(resp)
+	}
+}
+
+func doPost(ctx context.Context, client httpClient, req *http.Request, parser responseParser, d Debug) error {
+	req = req.WithContext(ctx)
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	err = checkStatusCode(resp, d)
+	if err != nil {
+		return err
+	}
+
+	return parser(resp)
+}
+
+// post JSON.
+func postJSON(ctx context.Context, client httpClient, endpoint, token string, json []byte, intf interface{}, d Debug) error {
+	reqBody := bytes.NewBuffer(json)
+	req, err := http.NewRequest("POST", endpoint, reqBody)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
+
+	return doPost(ctx, client, req, newJSONParser(intf), d)
+}
+
+// post a url encoded form.
+func postForm(ctx context.Context, client httpClient, endpoint string, values url.Values, intf interface{}, d Debug) error {
+	reqBody := strings.NewReader(values.Encode())
+	req, err := http.NewRequest("POST", endpoint, reqBody)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	return doPost(ctx, client, req, newJSONParser(intf), d)
+}
+
+func getResource(ctx context.Context, client httpClient, endpoint string, values url.Values, intf interface{}, d Debug) error {
+	req, err := http.NewRequest("GET", endpoint, nil)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.URL.RawQuery = values.Encode()
+
+	return doPost(ctx, client, req, newJSONParser(intf), d)
+}
+
+func parseAdminResponse(ctx context.Context, client httpClient, method string, teamName string, values url.Values, intf interface{}, d Debug) error {
+	endpoint := fmt.Sprintf(WEBAPIURLFormat, teamName, method, time.Now().Unix())
+	return postForm(ctx, client, endpoint, values, intf, d)
+}
+
+func logResponse(resp *http.Response, d Debug) error {
+	if d.Debug() {
+		text, err := httputil.DumpResponse(resp, true)
+		if err != nil {
+			return err
+		}
+		d.Debugln(string(text))
+	}
+
+	return nil
+}
+
+func okJSONHandler(rw http.ResponseWriter, r *http.Request) {
+	rw.Header().Set("Content-Type", "application/json")
+	response, _ := json.Marshal(SlackResponse{
+		Ok: true,
+	})
+	rw.Write(response)
+}
+
+// timerReset safely reset a timer, see time.Timer.Reset for details.
+func timerReset(t *time.Timer, d time.Duration) {
+	if !t.Stop() {
+		<-t.C
+	}
+	t.Reset(d)
+}
+
+func checkStatusCode(resp *http.Response, d Debug) error {
+	if resp.StatusCode == http.StatusTooManyRequests {
+		retry, err := strconv.ParseInt(resp.Header.Get("Retry-After"), 10, 64)
+		if err != nil {
+			return err
+		}
+		return &RateLimitedError{time.Duration(retry) * time.Second}
+	}
+
+	// Slack seems to send an HTML body along with 5xx error codes. Don't parse it.
+	if resp.StatusCode != http.StatusOK {
+		logResponse(resp, d)
+		return misc.StatusCodeError{Code: resp.StatusCode, Status: resp.Status}
+	}
+
+	return nil
+}
+
+type responseParser func(*http.Response) error
+
+func newJSONParser(dst interface{}) responseParser {
+	return func(resp *http.Response) error {
+		return json.NewDecoder(resp.Body).Decode(dst)
+	}
+}
+
+func newTextParser(dst interface{}) responseParser {
+	return func(resp *http.Response) error {
+		b, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			return err
+		}
+
+		if !bytes.Equal(b, []byte("ok")) {
+			return errors.New(string(b))
+		}
+
+		return nil
+	}
+}
+
+func newContentTypeParser(dst interface{}) responseParser {
+	return func(req *http.Response) (err error) {
+		var (
+			ctype string
+		)
+
+		if ctype, _, err = mime.ParseMediaType(req.Header.Get("Content-Type")); err != nil {
+			return err
+		}
+
+		switch ctype {
+		case "application/json":
+			return newJSONParser(dst)(req)
+		default:
+			return newTextParser(dst)(req)
+		}
+	}
+}

backend/vendor/github.com/slack-go/slack/oauth.go

@@ -0,0 +1,134 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+// OAuthResponseIncomingWebhook ...
+type OAuthResponseIncomingWebhook struct {
+	URL              string `json:"url"`
+	Channel          string `json:"channel"`
+	ChannelID        string `json:"channel_id,omitempty"`
+	ConfigurationURL string `json:"configuration_url"`
+}
+
+// OAuthResponseBot ...
+type OAuthResponseBot struct {
+	BotUserID      string `json:"bot_user_id"`
+	BotAccessToken string `json:"bot_access_token"`
+}
+
+// OAuthResponse ...
+type OAuthResponse struct {
+	AccessToken     string                       `json:"access_token"`
+	Scope           string                       `json:"scope"`
+	TeamName        string                       `json:"team_name"`
+	TeamID          string                       `json:"team_id"`
+	IncomingWebhook OAuthResponseIncomingWebhook `json:"incoming_webhook"`
+	Bot             OAuthResponseBot             `json:"bot"`
+	UserID          string                       `json:"user_id,omitempty"`
+	SlackResponse
+}
+
+// OAuthV2Response ...
+type OAuthV2Response struct {
+	AccessToken     string                       `json:"access_token"`
+	TokenType       string                       `json:"token_type"`
+	Scope           string                       `json:"scope"`
+	BotUserID       string                       `json:"bot_user_id"`
+	AppID           string                       `json:"app_id"`
+	Team            OAuthV2ResponseTeam          `json:"team"`
+	IncomingWebhook OAuthResponseIncomingWebhook `json:"incoming_webhook"`
+	Enterprise      OAuthV2ResponseEnterprise    `json:"enterprise"`
+	AuthedUser      OAuthV2ResponseAuthedUser    `json:"authed_user"`
+	SlackResponse
+}
+
+// OAuthV2ResponseTeam ...
+type OAuthV2ResponseTeam struct {
+	ID   string `json:"id"`
+	Name string `json:"name"`
+}
+
+// OAuthV2ResponseEnterprise ...
+type OAuthV2ResponseEnterprise struct {
+	ID   string `json:"id"`
+	Name string `json:"name"`
+}
+
+// OAuthV2ResponseAuthedUser ...
+type OAuthV2ResponseAuthedUser struct {
+	ID          string `json:"id"`
+	Scope       string `json:"scope"`
+	AccessToken string `json:"access_token"`
+	TokenType   string `json:"token_type"`
+}
+
+// GetOAuthToken retrieves an AccessToken
+func GetOAuthToken(client httpClient, clientID, clientSecret, code, redirectURI string) (accessToken string, scope string, err error) {
+	return GetOAuthTokenContext(context.Background(), client, clientID, clientSecret, code, redirectURI)
+}
+
+// GetOAuthTokenContext retrieves an AccessToken with a custom context
+func GetOAuthTokenContext(ctx context.Context, client httpClient, clientID, clientSecret, code, redirectURI string) (accessToken string, scope string, err error) {
+	response, err := GetOAuthResponseContext(ctx, client, clientID, clientSecret, code, redirectURI)
+	if err != nil {
+		return "", "", err
+	}
+	return response.AccessToken, response.Scope, nil
+}
+
+// GetBotOAuthToken retrieves top-level and bot AccessToken - https://api.slack.com/legacy/oauth#bot_user_access_tokens
+func GetBotOAuthToken(client httpClient, clientID, clientSecret, code, redirectURI string) (accessToken string, scope string, bot OAuthResponseBot, err error) {
+	return GetBotOAuthTokenContext(context.Background(), client, clientID, clientSecret, code, redirectURI)
+}
+
+// GetBotOAuthTokenContext retrieves top-level and bot AccessToken with a custom context
+func GetBotOAuthTokenContext(ctx context.Context, client httpClient, clientID, clientSecret, code, redirectURI string) (accessToken string, scope string, bot OAuthResponseBot, err error) {
+	response, err := GetOAuthResponseContext(ctx, client, clientID, clientSecret, code, redirectURI)
+	if err != nil {
+		return "", "", OAuthResponseBot{}, err
+	}
+	return response.AccessToken, response.Scope, response.Bot, nil
+}
+
+// GetOAuthResponse retrieves OAuth response
+func GetOAuthResponse(client httpClient, clientID, clientSecret, code, redirectURI string) (resp *OAuthResponse, err error) {
+	return GetOAuthResponseContext(context.Background(), client, clientID, clientSecret, code, redirectURI)
+}
+
+// GetOAuthResponseContext retrieves OAuth response with custom context
+func GetOAuthResponseContext(ctx context.Context, client httpClient, clientID, clientSecret, code, redirectURI string) (resp *OAuthResponse, err error) {
+	values := url.Values{
+		"client_id":     {clientID},
+		"client_secret": {clientSecret},
+		"code":          {code},
+		"redirect_uri":  {redirectURI},
+	}
+	response := &OAuthResponse{}
+	if err = postForm(ctx, client, APIURL+"oauth.access", values, response, discard{}); err != nil {
+		return nil, err
+	}
+	return response, response.Err()
+}
+
+// GetOAuthV2Response gets a V2 OAuth access token response - https://api.slack.com/methods/oauth.v2.access
+func GetOAuthV2Response(client httpClient, clientID, clientSecret, code, redirectURI string) (resp *OAuthV2Response, err error) {
+	return GetOAuthV2ResponseContext(context.Background(), client, clientID, clientSecret, code, redirectURI)
+}
+
+// GetOAuthV2ResponseContext with a context, gets a V2 OAuth access token response
+func GetOAuthV2ResponseContext(ctx context.Context, client httpClient, clientID, clientSecret, code, redirectURI string) (resp *OAuthV2Response, err error) {
+	values := url.Values{
+		"client_id":     {clientID},
+		"client_secret": {clientSecret},
+		"code":          {code},
+		"redirect_uri":  {redirectURI},
+	}
+	response := &OAuthV2Response{}
+	if err = postForm(ctx, client, APIURL+"oauth.v2.access", values, response, discard{}); err != nil {
+		return nil, err
+	}
+	return response, response.Err()
+}

backend/vendor/github.com/slack-go/slack/pagination.go

@@ -0,0 +1,20 @@
+package slack
+
+// Paging contains paging information
+type Paging struct {
+	Count int `json:"count"`
+	Total int `json:"total"`
+	Page  int `json:"page"`
+	Pages int `json:"pages"`
+}
+
+// Pagination contains pagination information
+// This is different from Paging in that it contains additional details
+type Pagination struct {
+	TotalCount int `json:"total_count"`
+	Page       int `json:"page"`
+	PerPage    int `json:"per_page"`
+	PageCount  int `json:"page_count"`
+	First      int `json:"first"`
+	Last       int `json:"last"`
+}

backend/vendor/github.com/slack-go/slack/pins.go

@@ -0,0 +1,94 @@
+package slack
+
+import (
+	"context"
+	"errors"
+	"net/url"
+)
+
+type listPinsResponseFull struct {
+	Items  []Item
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+// AddPin pins an item in a channel
+func (api *Client) AddPin(channel string, item ItemRef) error {
+	return api.AddPinContext(context.Background(), channel, item)
+}
+
+// AddPinContext pins an item in a channel with a custom context
+func (api *Client) AddPinContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "pins.add", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// RemovePin un-pins an item from a channel
+func (api *Client) RemovePin(channel string, item ItemRef) error {
+	return api.RemovePinContext(context.Background(), channel, item)
+}
+
+// RemovePinContext un-pins an item from a channel with a custom context
+func (api *Client) RemovePinContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "pins.remove", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// ListPins returns information about the items a user reacted to.
+func (api *Client) ListPins(channel string) ([]Item, *Paging, error) {
+	return api.ListPinsContext(context.Background(), channel)
+}
+
+// ListPinsContext returns information about the items a user reacted to with a custom context.
+func (api *Client) ListPinsContext(ctx context.Context, channel string) ([]Item, *Paging, error) {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+
+	response := &listPinsResponseFull{}
+	err := api.postMethod(ctx, "pins.list", values, response)
+	if err != nil {
+		return nil, nil, err
+	}
+	if !response.Ok {
+		return nil, nil, errors.New(response.Error)
+	}
+	return response.Items, &response.Paging, nil
+}

backend/vendor/github.com/slack-go/slack/reactions.go

@@ -0,0 +1,270 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+// ItemReaction is the reactions that have happened on an item.
+type ItemReaction struct {
+	Name  string   `json:"name"`
+	Count int      `json:"count"`
+	Users []string `json:"users"`
+}
+
+// ReactedItem is an item that was reacted to, and the details of the
+// reactions.
+type ReactedItem struct {
+	Item
+	Reactions []ItemReaction
+}
+
+// GetReactionsParameters is the inputs to get reactions to an item.
+type GetReactionsParameters struct {
+	Full bool
+}
+
+// NewGetReactionsParameters initializes the inputs to get reactions to an item.
+func NewGetReactionsParameters() GetReactionsParameters {
+	return GetReactionsParameters{
+		Full: false,
+	}
+}
+
+type getReactionsResponseFull struct {
+	Type string
+	M    struct {
+		Reactions []ItemReaction
+	} `json:"message"`
+	F struct {
+		Reactions []ItemReaction
+	} `json:"file"`
+	FC struct {
+		Reactions []ItemReaction
+	} `json:"comment"`
+	SlackResponse
+}
+
+func (res getReactionsResponseFull) extractReactions() []ItemReaction {
+	switch res.Type {
+	case "message":
+		return res.M.Reactions
+	case "file":
+		return res.F.Reactions
+	case "file_comment":
+		return res.FC.Reactions
+	}
+	return []ItemReaction{}
+}
+
+const (
+	DEFAULT_REACTIONS_USER  = ""
+	DEFAULT_REACTIONS_COUNT = 100
+	DEFAULT_REACTIONS_PAGE  = 1
+	DEFAULT_REACTIONS_FULL  = false
+)
+
+// ListReactionsParameters is the inputs to find all reactions by a user.
+type ListReactionsParameters struct {
+	User  string
+	Count int
+	Page  int
+	Full  bool
+}
+
+// NewListReactionsParameters initializes the inputs to find all reactions
+// performed by a user.
+func NewListReactionsParameters() ListReactionsParameters {
+	return ListReactionsParameters{
+		User:  DEFAULT_REACTIONS_USER,
+		Count: DEFAULT_REACTIONS_COUNT,
+		Page:  DEFAULT_REACTIONS_PAGE,
+		Full:  DEFAULT_REACTIONS_FULL,
+	}
+}
+
+type listReactionsResponseFull struct {
+	Items []struct {
+		Type    string
+		Channel string
+		M       struct {
+			*Message
+		} `json:"message"`
+		F struct {
+			*File
+			Reactions []ItemReaction
+		} `json:"file"`
+		FC struct {
+			*Comment
+			Reactions []ItemReaction
+		} `json:"comment"`
+	}
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+func (res listReactionsResponseFull) extractReactedItems() []ReactedItem {
+	items := make([]ReactedItem, len(res.Items))
+	for i, input := range res.Items {
+		item := ReactedItem{}
+		item.Type = input.Type
+		switch input.Type {
+		case "message":
+			item.Channel = input.Channel
+			item.Message = input.M.Message
+			item.Reactions = input.M.Reactions
+		case "file":
+			item.File = input.F.File
+			item.Reactions = input.F.Reactions
+		case "file_comment":
+			item.File = input.F.File
+			item.Comment = input.FC.Comment
+			item.Reactions = input.FC.Reactions
+		}
+		items[i] = item
+	}
+	return items
+}
+
+// AddReaction adds a reaction emoji to a message, file or file comment.
+func (api *Client) AddReaction(name string, item ItemRef) error {
+	return api.AddReactionContext(context.Background(), name, item)
+}
+
+// AddReactionContext adds a reaction emoji to a message, file or file comment with a custom context.
+func (api *Client) AddReactionContext(ctx context.Context, name string, item ItemRef) error {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if name != "" {
+		values.Set("name", name)
+	}
+	if item.Channel != "" {
+		values.Set("channel", item.Channel)
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "reactions.add", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// RemoveReaction removes a reaction emoji from a message, file or file comment.
+func (api *Client) RemoveReaction(name string, item ItemRef) error {
+	return api.RemoveReactionContext(context.Background(), name, item)
+}
+
+// RemoveReactionContext removes a reaction emoji from a message, file or file comment with a custom context.
+func (api *Client) RemoveReactionContext(ctx context.Context, name string, item ItemRef) error {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if name != "" {
+		values.Set("name", name)
+	}
+	if item.Channel != "" {
+		values.Set("channel", item.Channel)
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "reactions.remove", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// GetReactions returns details about the reactions on an item.
+func (api *Client) GetReactions(item ItemRef, params GetReactionsParameters) ([]ItemReaction, error) {
+	return api.GetReactionsContext(context.Background(), item, params)
+}
+
+// GetReactionsContext returns details about the reactions on an item with a custom context
+func (api *Client) GetReactionsContext(ctx context.Context, item ItemRef, params GetReactionsParameters) ([]ItemReaction, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if item.Channel != "" {
+		values.Set("channel", item.Channel)
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+	if params.Full != DEFAULT_REACTIONS_FULL {
+		values.Set("full", strconv.FormatBool(params.Full))
+	}
+
+	response := &getReactionsResponseFull{}
+	if err := api.postMethod(ctx, "reactions.get", values, response); err != nil {
+		return nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, err
+	}
+
+	return response.extractReactions(), nil
+}
+
+// ListReactions returns information about the items a user reacted to.
+func (api *Client) ListReactions(params ListReactionsParameters) ([]ReactedItem, *Paging, error) {
+	return api.ListReactionsContext(context.Background(), params)
+}
+
+// ListReactionsContext returns information about the items a user reacted to with a custom context.
+func (api *Client) ListReactionsContext(ctx context.Context, params ListReactionsParameters) ([]ReactedItem, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.User != DEFAULT_REACTIONS_USER {
+		values.Add("user", params.User)
+	}
+	if params.Count != DEFAULT_REACTIONS_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_REACTIONS_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+	if params.Full != DEFAULT_REACTIONS_FULL {
+		values.Add("full", strconv.FormatBool(params.Full))
+	}
+
+	response := &listReactionsResponseFull{}
+	err := api.postMethod(ctx, "reactions.list", values, response)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, nil, err
+	}
+
+	return response.extractReactedItems(), &response.Paging, nil
+}

backend/vendor/github.com/slack-go/slack/reminders.go

@@ -0,0 +1,104 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+type Reminder struct {
+	ID         string `json:"id"`
+	Creator    string `json:"creator"`
+	User       string `json:"user"`
+	Text       string `json:"text"`
+	Recurring  bool   `json:"recurring"`
+	Time       int    `json:"time"`
+	CompleteTS int    `json:"complete_ts"`
+}
+
+type reminderResp struct {
+	SlackResponse
+	Reminder Reminder `json:"reminder"`
+}
+
+type remindersResp struct {
+	SlackResponse
+	Reminders []*Reminder `json:"reminders"`
+}
+
+func (api *Client) doReminder(ctx context.Context, path string, values url.Values) (*Reminder, error) {
+	response := &reminderResp{}
+	if err := api.postMethod(ctx, path, values, response); err != nil {
+		return nil, err
+	}
+	return &response.Reminder, response.Err()
+}
+
+func (api *Client) doReminders(ctx context.Context, path string, values url.Values) ([]*Reminder, error) {
+	response := &remindersResp{}
+	if err := api.postMethod(ctx, path, values, response); err != nil {
+		return nil, err
+	}
+
+	// create an array of pointers to reminders
+	var reminders = make([]*Reminder, 0, len(response.Reminders))
+	for _, reminder := range response.Reminders {
+		reminders = append(reminders, reminder)
+	}
+
+	return reminders, response.Err()
+}
+
+// ListReminders lists all the reminders created by or for the authenticated user
+//
+// See https://api.slack.com/methods/reminders.list
+func (api *Client) ListReminders() ([]*Reminder, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	return api.doReminders(context.Background(), "reminders.list", values)
+}
+
+// AddChannelReminder adds a reminder for a channel.
+//
+// See https://api.slack.com/methods/reminders.add (NOTE: the ability to set
+// reminders on a channel is currently undocumented but has been tested to
+// work)
+func (api *Client) AddChannelReminder(channelID, text, time string) (*Reminder, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"text":    {text},
+		"time":    {time},
+		"channel": {channelID},
+	}
+	return api.doReminder(context.Background(), "reminders.add", values)
+}
+
+// AddUserReminder adds a reminder for a user.
+//
+// See https://api.slack.com/methods/reminders.add (NOTE: the ability to set
+// reminders on a channel is currently undocumented but has been tested to
+// work)
+func (api *Client) AddUserReminder(userID, text, time string) (*Reminder, error) {
+	values := url.Values{
+		"token": {api.token},
+		"text":  {text},
+		"time":  {time},
+		"user":  {userID},
+	}
+	return api.doReminder(context.Background(), "reminders.add", values)
+}
+
+// DeleteReminder deletes an existing reminder.
+//
+// See https://api.slack.com/methods/reminders.delete
+func (api *Client) DeleteReminder(id string) error {
+	values := url.Values{
+		"token":    {api.token},
+		"reminder": {id},
+	}
+	response := &SlackResponse{}
+	if err := api.postMethod(context.Background(), "reminders.delete", values, response); err != nil {
+		return err
+	}
+	return response.Err()
+}

backend/vendor/github.com/slack-go/slack/rtm.go

@@ -0,0 +1,131 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"sync"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	websocketDefaultTimeout = 10 * time.Second
+	defaultPingInterval     = 30 * time.Second
+)
+
+const (
+	rtmEventTypeAck                 = ""
+	rtmEventTypeHello               = "hello"
+	rtmEventTypeGoodbye             = "goodbye"
+	rtmEventTypePong                = "pong"
+	rtmEventTypeDesktopNotification = "desktop_notification"
+)
+
+// StartRTM calls the "rtm.start" endpoint and returns the provided URL and the full Info block.
+//
+// To have a fully managed Websocket connection, use `NewRTM`, and call `ManageConnection()` on it.
+func (api *Client) StartRTM() (info *Info, websocketURL string, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), websocketDefaultTimeout)
+	defer cancel()
+
+	return api.StartRTMContext(ctx)
+}
+
+// StartRTMContext calls the "rtm.start" endpoint and returns the provided URL and the full Info block with a custom context.
+//
+// To have a fully managed Websocket connection, use `NewRTM`, and call `ManageConnection()` on it.
+func (api *Client) StartRTMContext(ctx context.Context) (info *Info, websocketURL string, err error) {
+	response := &infoResponseFull{}
+	err = api.postMethod(ctx, "rtm.start", url.Values{"token": {api.token}}, response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	api.Debugln("Using URL:", response.Info.URL)
+	return &response.Info, response.Info.URL, response.Err()
+}
+
+// ConnectRTM calls the "rtm.connect" endpoint and returns the provided URL and the compact Info block.
+//
+// To have a fully managed Websocket connection, use `NewRTM`, and call `ManageConnection()` on it.
+func (api *Client) ConnectRTM() (info *Info, websocketURL string, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), websocketDefaultTimeout)
+	defer cancel()
+
+	return api.ConnectRTMContext(ctx)
+}
+
+// ConnectRTMContext calls the "rtm.connect" endpoint and returns the
+// provided URL and the compact Info block with a custom context.
+//
+// To have a fully managed Websocket connection, use `NewRTM`, and call `ManageConnection()` on it.
+func (api *Client) ConnectRTMContext(ctx context.Context) (info *Info, websocketURL string, err error) {
+	response := &infoResponseFull{}
+	err = api.postMethod(ctx, "rtm.connect", url.Values{"token": {api.token}}, response)
+	if err != nil {
+		api.Debugf("Failed to connect to RTM: %s", err)
+		return nil, "", err
+	}
+
+	api.Debugln("Using URL:", response.Info.URL)
+	return &response.Info, response.Info.URL, response.Err()
+}
+
+// RTMOption options for the managed RTM.
+type RTMOption func(*RTM)
+
+// RTMOptionUseStart as of 11th July 2017 you should prefer setting this to false, see:
+// https://api.slack.com/changelog/2017-04-start-using-rtm-connect-and-stop-using-rtm-start
+func RTMOptionUseStart(b bool) RTMOption {
+	return func(rtm *RTM) {
+		rtm.useRTMStart = b
+	}
+}
+
+// RTMOptionDialer takes a gorilla websocket Dialer and uses it as the
+// Dialer when opening the websocket for the RTM connection.
+func RTMOptionDialer(d *websocket.Dialer) RTMOption {
+	return func(rtm *RTM) {
+		rtm.dialer = d
+	}
+}
+
+// RTMOptionPingInterval determines how often to deliver a ping message to slack.
+func RTMOptionPingInterval(d time.Duration) RTMOption {
+	return func(rtm *RTM) {
+		rtm.pingInterval = d
+		rtm.resetDeadman()
+	}
+}
+
+// RTMOptionConnParams installs parameters to embed into the connection URL.
+func RTMOptionConnParams(connParams url.Values) RTMOption {
+	return func(rtm *RTM) {
+		rtm.connParams = connParams
+	}
+}
+
+// NewRTM returns a RTM, which provides a fully managed connection to
+// Slack's websocket-based Real-Time Messaging protocol.
+func (api *Client) NewRTM(options ...RTMOption) *RTM {
+	result := &RTM{
+		Client:           *api,
+		IncomingEvents:   make(chan RTMEvent, 50),
+		outgoingMessages: make(chan OutgoingMessage, 20),
+		pingInterval:     defaultPingInterval,
+		pingDeadman:      time.NewTimer(deadmanDuration(defaultPingInterval)),
+		killChannel:      make(chan bool),
+		disconnected:     make(chan struct{}),
+		disconnectedm:    &sync.Once{},
+		forcePing:        make(chan bool),
+		idGen:            NewSafeID(1),
+		mu:               &sync.Mutex{},
+	}
+
+	for _, opt := range options {
+		opt(result)
+	}
+
+	return result
+}

backend/vendor/github.com/slack-go/slack/search.go

@@ -0,0 +1,156 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+const (
+	DEFAULT_SEARCH_SORT      = "score"
+	DEFAULT_SEARCH_SORT_DIR  = "desc"
+	DEFAULT_SEARCH_HIGHLIGHT = false
+	DEFAULT_SEARCH_COUNT     = 20
+	DEFAULT_SEARCH_PAGE      = 1
+)
+
+type SearchParameters struct {
+	Sort          string
+	SortDirection string
+	Highlight     bool
+	Count         int
+	Page          int
+}
+
+type CtxChannel struct {
+	ID                 string `json:"id"`
+	Name               string `json:"name"`
+	IsExtShared        bool   `json:"is_ext_shared"`
+	IsMPIM             bool   `json:"is_mpim"`
+	ISOrgShared        bool   `json:"is_org_shared"`
+	IsPendingExtShared bool   `json:"is_pending_ext_shared"`
+	IsPrivate          bool   `json:"is_private"`
+	IsShared           bool   `json:"is_shared"`
+}
+
+type CtxMessage struct {
+	User      string `json:"user"`
+	Username  string `json:"username"`
+	Text      string `json:"text"`
+	Timestamp string `json:"ts"`
+	Type      string `json:"type"`
+}
+
+type SearchMessage struct {
+	Type        string       `json:"type"`
+	Channel     CtxChannel   `json:"channel"`
+	User        string       `json:"user"`
+	Username    string       `json:"username"`
+	Timestamp   string       `json:"ts"`
+	Blocks      Blocks       `json:"blocks,omitempty"`
+	Text        string       `json:"text"`
+	Permalink   string       `json:"permalink"`
+	Attachments []Attachment `json:"attachments"`
+	Previous    CtxMessage   `json:"previous"`
+	Previous2   CtxMessage   `json:"previous_2"`
+	Next        CtxMessage   `json:"next"`
+	Next2       CtxMessage   `json:"next_2"`
+}
+
+type SearchMessages struct {
+	Matches    []SearchMessage `json:"matches"`
+	Paging     `json:"paging"`
+	Pagination `json:"pagination"`
+	Total      int `json:"total"`
+}
+
+type SearchFiles struct {
+	Matches    []File `json:"matches"`
+	Paging     `json:"paging"`
+	Pagination `json:"pagination"`
+	Total      int `json:"total"`
+}
+
+type searchResponseFull struct {
+	Query          string `json:"query"`
+	SearchMessages `json:"messages"`
+	SearchFiles    `json:"files"`
+	SlackResponse
+}
+
+func NewSearchParameters() SearchParameters {
+	return SearchParameters{
+		Sort:          DEFAULT_SEARCH_SORT,
+		SortDirection: DEFAULT_SEARCH_SORT_DIR,
+		Highlight:     DEFAULT_SEARCH_HIGHLIGHT,
+		Count:         DEFAULT_SEARCH_COUNT,
+		Page:          DEFAULT_SEARCH_PAGE,
+	}
+}
+
+func (api *Client) _search(ctx context.Context, path, query string, params SearchParameters, files, messages bool) (response *searchResponseFull, error error) {
+	values := url.Values{
+		"token": {api.token},
+		"query": {query},
+	}
+	if params.Sort != DEFAULT_SEARCH_SORT {
+		values.Add("sort", params.Sort)
+	}
+	if params.SortDirection != DEFAULT_SEARCH_SORT_DIR {
+		values.Add("sort_dir", params.SortDirection)
+	}
+	if params.Highlight != DEFAULT_SEARCH_HIGHLIGHT {
+		values.Add("highlight", strconv.Itoa(1))
+	}
+	if params.Count != DEFAULT_SEARCH_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_SEARCH_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+
+	response = &searchResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+
+}
+
+func (api *Client) Search(query string, params SearchParameters) (*SearchMessages, *SearchFiles, error) {
+	return api.SearchContext(context.Background(), query, params)
+}
+
+func (api *Client) SearchContext(ctx context.Context, query string, params SearchParameters) (*SearchMessages, *SearchFiles, error) {
+	response, err := api._search(ctx, "search.all", query, params, true, true)
+	if err != nil {
+		return nil, nil, err
+	}
+	return &response.SearchMessages, &response.SearchFiles, nil
+}
+
+func (api *Client) SearchFiles(query string, params SearchParameters) (*SearchFiles, error) {
+	return api.SearchFilesContext(context.Background(), query, params)
+}
+
+func (api *Client) SearchFilesContext(ctx context.Context, query string, params SearchParameters) (*SearchFiles, error) {
+	response, err := api._search(ctx, "search.files", query, params, true, false)
+	if err != nil {
+		return nil, err
+	}
+	return &response.SearchFiles, nil
+}
+
+func (api *Client) SearchMessages(query string, params SearchParameters) (*SearchMessages, error) {
+	return api.SearchMessagesContext(context.Background(), query, params)
+}
+
+func (api *Client) SearchMessagesContext(ctx context.Context, query string, params SearchParameters) (*SearchMessages, error) {
+	response, err := api._search(ctx, "search.messages", query, params, false, true)
+	if err != nil {
+		return nil, err
+	}
+	return &response.SearchMessages, nil
+}

backend/vendor/github.com/slack-go/slack/security.go

@@ -0,0 +1,108 @@
+package slack
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"hash"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Signature headers
+const (
+	hSignature = "X-Slack-Signature"
+	hTimestamp = "X-Slack-Request-Timestamp"
+)
+
+// SecretsVerifier contains the information needed to verify that the request comes from Slack
+type SecretsVerifier struct {
+	d         Debug
+	signature []byte
+	hmac      hash.Hash
+}
+
+func unsafeSignatureVerifier(header http.Header, secret string) (_ SecretsVerifier, err error) {
+	var (
+		bsignature []byte
+	)
+
+	signature := header.Get(hSignature)
+	stimestamp := header.Get(hTimestamp)
+
+	if signature == "" || stimestamp == "" {
+		return SecretsVerifier{}, ErrMissingHeaders
+	}
+
+	if bsignature, err = hex.DecodeString(strings.TrimPrefix(signature, "v0=")); err != nil {
+		return SecretsVerifier{}, err
+	}
+
+	hash := hmac.New(sha256.New, []byte(secret))
+	if _, err = hash.Write([]byte(fmt.Sprintf("v0:%s:", stimestamp))); err != nil {
+		return SecretsVerifier{}, err
+	}
+
+	return SecretsVerifier{
+		signature: bsignature,
+		hmac:      hash,
+	}, nil
+}
+
+// NewSecretsVerifier returns a SecretsVerifier object in exchange for an http.Header object and signing secret
+func NewSecretsVerifier(header http.Header, secret string) (sv SecretsVerifier, err error) {
+	var (
+		timestamp int64
+	)
+
+	stimestamp := header.Get(hTimestamp)
+
+	if sv, err = unsafeSignatureVerifier(header, secret); err != nil {
+		return SecretsVerifier{}, err
+	}
+
+	if timestamp, err = strconv.ParseInt(stimestamp, 10, 64); err != nil {
+		return SecretsVerifier{}, err
+	}
+
+	diff := absDuration(time.Since(time.Unix(timestamp, 0)))
+	if diff > 5*time.Minute {
+		return SecretsVerifier{}, ErrExpiredTimestamp
+	}
+
+	return sv, err
+}
+
+func (v *SecretsVerifier) WithDebug(d Debug) *SecretsVerifier {
+	v.d = d
+	return v
+}
+
+func (v *SecretsVerifier) Write(body []byte) (n int, err error) {
+	return v.hmac.Write(body)
+}
+
+// Ensure compares the signature sent from Slack with the actual computed hash to judge validity
+func (v SecretsVerifier) Ensure() error {
+	computed := v.hmac.Sum(nil)
+	// use hmac.Equal prevent leaking timing information.
+	if hmac.Equal(computed, v.signature) {
+		return nil
+	}
+	if v.d != nil && v.d.Debug() {
+		v.d.Debugln(fmt.Sprintf("Expected signing signature: %s, but computed: %s", hex.EncodeToString(v.signature), hex.EncodeToString(computed)))
+	}
+	return fmt.Errorf("Computed unexpected signature of: %s", hex.EncodeToString(computed))
+}
+
+func abs64(n int64) int64 {
+	y := n >> 63
+	return (n ^ y) - y
+}
+
+func absDuration(n time.Duration) time.Duration {
+	return time.Duration(abs64(int64(n)))
+}

backend/vendor/github.com/slack-go/slack/slack.go

@@ -0,0 +1,162 @@
+package slack
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+)
+
+const (
+	// APIURL of the slack api.
+	APIURL = "https://slack.com/api/"
+	// WEBAPIURLFormat ...
+	WEBAPIURLFormat = "https://%s.slack.com/api/users.admin.%s?t=%d"
+)
+
+// httpClient defines the minimal interface needed for an http.Client to be implemented.
+type httpClient interface {
+	Do(*http.Request) (*http.Response, error)
+}
+
+// ResponseMetadata holds pagination metadata
+type ResponseMetadata struct {
+	Cursor   string   `json:"next_cursor"`
+	Messages []string `json:"messages"`
+	Warnings []string `json:"warnings"`
+}
+
+func (t *ResponseMetadata) initialize() *ResponseMetadata {
+	if t != nil {
+		return t
+	}
+
+	return &ResponseMetadata{}
+}
+
+// AuthTestResponse ...
+type AuthTestResponse struct {
+	URL    string `json:"url"`
+	Team   string `json:"team"`
+	User   string `json:"user"`
+	TeamID string `json:"team_id"`
+	UserID string `json:"user_id"`
+	// EnterpriseID is only returned when an enterprise id present
+	EnterpriseID string `json:"enterprise_id,omitempty"`
+	BotID        string `json:"bot_id"`
+}
+
+type authTestResponseFull struct {
+	SlackResponse
+	AuthTestResponse
+}
+
+// Client for the slack api.
+type ParamOption func(*url.Values)
+
+type Client struct {
+	token         string
+	appLevelToken string
+	endpoint      string
+	debug         bool
+	log           ilogger
+	httpclient    httpClient
+}
+
+// Option defines an option for a Client
+type Option func(*Client)
+
+// OptionHTTPClient - provide a custom http client to the slack client.
+func OptionHTTPClient(client httpClient) func(*Client) {
+	return func(c *Client) {
+		c.httpclient = client
+	}
+}
+
+// OptionDebug enable debugging for the client
+func OptionDebug(b bool) func(*Client) {
+	return func(c *Client) {
+		c.debug = b
+	}
+}
+
+// OptionLog set logging for client.
+func OptionLog(l logger) func(*Client) {
+	return func(c *Client) {
+		c.log = internalLog{logger: l}
+	}
+}
+
+// OptionAPIURL set the url for the client. only useful for testing.
+func OptionAPIURL(u string) func(*Client) {
+	return func(c *Client) { c.endpoint = u }
+}
+
+// OptionAppLevelToken sets an app-level token for the client.
+func OptionAppLevelToken(token string) func(*Client) {
+	return func(c *Client) { c.appLevelToken = token }
+}
+
+// New builds a slack client from the provided token and options.
+func New(token string, options ...Option) *Client {
+	s := &Client{
+		token:      token,
+		endpoint:   APIURL,
+		httpclient: &http.Client{},
+		log:        log.New(os.Stderr, "slack-go/slack", log.LstdFlags|log.Lshortfile),
+	}
+
+	for _, opt := range options {
+		opt(s)
+	}
+
+	return s
+}
+
+// AuthTest tests if the user is able to do authenticated requests or not
+func (api *Client) AuthTest() (response *AuthTestResponse, error error) {
+	return api.AuthTestContext(context.Background())
+}
+
+// AuthTestContext tests if the user is able to do authenticated requests or not with a custom context
+func (api *Client) AuthTestContext(ctx context.Context) (response *AuthTestResponse, err error) {
+	api.Debugf("Challenging auth...")
+	responseFull := &authTestResponseFull{}
+	err = api.postMethod(ctx, "auth.test", url.Values{"token": {api.token}}, responseFull)
+	if err != nil {
+		return nil, err
+	}
+
+	return &responseFull.AuthTestResponse, responseFull.Err()
+}
+
+// Debugf print a formatted debug line.
+func (api *Client) Debugf(format string, v ...interface{}) {
+	if api.debug {
+		api.log.Output(2, fmt.Sprintf(format, v...))
+	}
+}
+
+// Debugln print a debug line.
+func (api *Client) Debugln(v ...interface{}) {
+	if api.debug {
+		api.log.Output(2, fmt.Sprintln(v...))
+	}
+}
+
+// Debug returns if debug is enabled.
+func (api *Client) Debug() bool {
+	return api.debug
+}
+
+// post to a slack web method.
+func (api *Client) postMethod(ctx context.Context, path string, values url.Values, intf interface{}) error {
+	return postForm(ctx, api.httpclient, api.endpoint+path, values, intf, api)
+}
+
+// get a slack web method.
+func (api *Client) getMethod(ctx context.Context, path string, values url.Values, intf interface{}) error {
+	return getResource(ctx, api.httpclient, api.endpoint+path, values, intf, api)
+}

backend/vendor/github.com/slack-go/slack/slackutilsx/slackutilsx.go

@@ -0,0 +1,62 @@
+// Package slackutilsx is a utility package that doesn't promise API stability.
+// its for experimental functionality and utilities.
+package slackutilsx
+
+import (
+	"strings"
+	"unicode/utf8"
+)
+
+// ChannelType the type of channel based on the channelID
+type ChannelType int
+
+func (t ChannelType) String() string {
+	switch t {
+	case CTypeDM:
+		return "Direct"
+	case CTypeGroup:
+		return "Group"
+	case CTypeChannel:
+		return "Channel"
+	default:
+		return "Unknown"
+	}
+}
+
+const (
+	// CTypeUnknown represents channels we cannot properly detect.
+	CTypeUnknown ChannelType = iota
+	// CTypeDM is a private channel between two slack users.
+	CTypeDM
+	// CTypeGroup is a group channel.
+	CTypeGroup
+	// CTypeChannel is a public channel.
+	CTypeChannel
+)
+
+// DetectChannelType converts a channelID to a ChannelType.
+// channelID must not be empty. However, if it is empty, the channel type will default to Unknown.
+func DetectChannelType(channelID string) ChannelType {
+	// intentionally ignore the error and just default to CTypeUnknown
+	switch r, _ := utf8.DecodeRuneInString(channelID); r {
+	case 'C':
+		return CTypeChannel
+	case 'G':
+		return CTypeGroup
+	case 'D':
+		return CTypeDM
+	default:
+		return CTypeUnknown
+	}
+}
+
+// EscapeMessage text
+func EscapeMessage(message string) string {
+	replacer := strings.NewReplacer("&", "&amp;", "<", "&lt;", ">", "&gt;")
+	return replacer.Replace(message)
+}
+
+// Retryable errors return true.
+type Retryable interface {
+	Retryable() bool
+}

backend/vendor/github.com/slack-go/slack/slash.go

@@ -0,0 +1,55 @@
+package slack
+
+import (
+	"net/http"
+)
+
+// SlashCommand contains information about a request of the slash command
+type SlashCommand struct {
+	Token          string `json:"token"`
+	TeamID         string `json:"team_id"`
+	TeamDomain     string `json:"team_domain"`
+	EnterpriseID   string `json:"enterprise_id,omitempty"`
+	EnterpriseName string `json:"enterprise_name,omitempty"`
+	ChannelID      string `json:"channel_id"`
+	ChannelName    string `json:"channel_name"`
+	UserID         string `json:"user_id"`
+	UserName       string `json:"user_name"`
+	Command        string `json:"command"`
+	Text           string `json:"text"`
+	ResponseURL    string `json:"response_url"`
+	TriggerID      string `json:"trigger_id"`
+	APIAppID       string `json:"api_app_id"`
+}
+
+// SlashCommandParse will parse the request of the slash command
+func SlashCommandParse(r *http.Request) (s SlashCommand, err error) {
+	if err = r.ParseForm(); err != nil {
+		return s, err
+	}
+	s.Token = r.PostForm.Get("token")
+	s.TeamID = r.PostForm.Get("team_id")
+	s.TeamDomain = r.PostForm.Get("team_domain")
+	s.EnterpriseID = r.PostForm.Get("enterprise_id")
+	s.EnterpriseName = r.PostForm.Get("enterprise_name")
+	s.ChannelID = r.PostForm.Get("channel_id")
+	s.ChannelName = r.PostForm.Get("channel_name")
+	s.UserID = r.PostForm.Get("user_id")
+	s.UserName = r.PostForm.Get("user_name")
+	s.Command = r.PostForm.Get("command")
+	s.Text = r.PostForm.Get("text")
+	s.ResponseURL = r.PostForm.Get("response_url")
+	s.TriggerID = r.PostForm.Get("trigger_id")
+	s.APIAppID = r.PostForm.Get("api_app_id")
+	return s, nil
+}
+
+// ValidateToken validates verificationTokens
+func (s SlashCommand) ValidateToken(verificationTokens ...string) bool {
+	for _, token := range verificationTokens {
+		if s.Token == token {
+			return true
+		}
+	}
+	return false
+}

backend/vendor/github.com/slack-go/slack/socket_mode.go

@@ -0,0 +1,34 @@
+package slack
+
+import (
+	"context"
+)
+
+// SocketModeConnection contains various details about the SocketMode connection.
+// It is returned by an "apps.connections.open" API call.
+type SocketModeConnection struct {
+	URL  string                 `json:"url,omitempty"`
+	Data map[string]interface{} `json:"-"`
+}
+
+type openResponseFull struct {
+	SlackResponse
+	SocketModeConnection
+}
+
+// StartSocketModeContext calls the "apps.connections.open" endpoint and returns the provided URL and the full Info block with a custom context.
+//
+// To have a fully managed Socket Mode connection, use `socketmode.New()`, and call `Run()` on it.
+func (api *Client) StartSocketModeContext(ctx context.Context) (info *SocketModeConnection, websocketURL string, err error) {
+	response := &openResponseFull{}
+	err = postJSON(ctx, api.httpclient, api.endpoint+"apps.connections.open", api.appLevelToken, nil, response, api)
+	if err != nil {
+		return nil, "", err
+	}
+
+	if response.Err() == nil {
+		api.Debugln("Using URL:", response.SocketModeConnection.URL)
+	}
+
+	return &response.SocketModeConnection, response.SocketModeConnection.URL, response.Err()
+}

backend/vendor/github.com/slack-go/slack/stars.go

@@ -0,0 +1,263 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+const (
+	DEFAULT_STARS_USER  = ""
+	DEFAULT_STARS_COUNT = 100
+	DEFAULT_STARS_PAGE  = 1
+)
+
+type StarsParameters struct {
+	User  string
+	Count int
+	Page  int
+}
+
+type StarredItem Item
+
+type listResponseFull struct {
+	Items  []Item `json:"items"`
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+// NewStarsParameters initialises StarsParameters with default values
+func NewStarsParameters() StarsParameters {
+	return StarsParameters{
+		User:  DEFAULT_STARS_USER,
+		Count: DEFAULT_STARS_COUNT,
+		Page:  DEFAULT_STARS_PAGE,
+	}
+}
+
+// AddStar stars an item in a channel
+func (api *Client) AddStar(channel string, item ItemRef) error {
+	return api.AddStarContext(context.Background(), channel, item)
+}
+
+// AddStarContext stars an item in a channel with a custom context
+func (api *Client) AddStarContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "stars.add", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// RemoveStar removes a starred item from a channel
+func (api *Client) RemoveStar(channel string, item ItemRef) error {
+	return api.RemoveStarContext(context.Background(), channel, item)
+}
+
+// RemoveStarContext removes a starred item from a channel with a custom context
+func (api *Client) RemoveStarContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "stars.remove", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// ListStars returns information about the stars a user added
+func (api *Client) ListStars(params StarsParameters) ([]Item, *Paging, error) {
+	return api.ListStarsContext(context.Background(), params)
+}
+
+// ListStarsContext returns information about the stars a user added with a custom context
+func (api *Client) ListStarsContext(ctx context.Context, params StarsParameters) ([]Item, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.User != DEFAULT_STARS_USER {
+		values.Add("user", params.User)
+	}
+	if params.Count != DEFAULT_STARS_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_STARS_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+
+	response := &listResponseFull{}
+	err := api.postMethod(ctx, "stars.list", values, response)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, nil, err
+	}
+
+	return response.Items, &response.Paging, nil
+}
+
+// GetStarred returns a list of StarredItem items.
+//
+// The user then has to iterate over them and figure out what they should
+// be looking at according to what is in the Type.
+//    for _, item := range items {
+//        switch c.Type {
+//        case "file_comment":
+//            log.Println(c.Comment)
+//        case "file":
+//             ...
+//
+//    }
+// This function still exists to maintain backwards compatibility.
+// I exposed it as returning []StarredItem, so it shall stay as StarredItem
+func (api *Client) GetStarred(params StarsParameters) ([]StarredItem, *Paging, error) {
+	return api.GetStarredContext(context.Background(), params)
+}
+
+// GetStarredContext returns a list of StarredItem items with a custom context
+//
+// For more details see GetStarred
+func (api *Client) GetStarredContext(ctx context.Context, params StarsParameters) ([]StarredItem, *Paging, error) {
+	items, paging, err := api.ListStarsContext(ctx, params)
+	if err != nil {
+		return nil, nil, err
+	}
+	starredItems := make([]StarredItem, len(items))
+	for i, item := range items {
+		starredItems[i] = StarredItem(item)
+	}
+	return starredItems, paging, nil
+}
+
+type listResponsePaginated struct {
+	Items []Item `json:"items"`
+	SlackResponse
+	Metadata ResponseMetadata `json:"response_metadata"`
+}
+
+// StarredItemPagination allows for paginating over the starred items
+type StarredItemPagination struct {
+	Items        []Item
+	limit        int
+	previousResp *ResponseMetadata
+	c            *Client
+}
+
+// ListStarsOption options for the GetUsers method call.
+type ListStarsOption func(*StarredItemPagination)
+
+// ListAllStars returns the complete list of starred items
+func (api *Client) ListAllStars() ([]Item, error) {
+	return api.ListAllStarsContext(context.Background())
+}
+
+// ListAllStarsContext returns the list of users (with their detailed information) with a custom context
+func (api *Client) ListAllStarsContext(ctx context.Context) (results []Item, err error) {
+	p := api.ListStarsPaginated()
+	for err == nil {
+		p, err = p.next(ctx)
+		if err == nil {
+			results = append(results, p.Items...)
+		} else if rateLimitedError, ok := err.(*RateLimitedError); ok {
+			select {
+			case <-ctx.Done():
+				err = ctx.Err()
+			case <-time.After(rateLimitedError.RetryAfter):
+				err = nil
+			}
+		}
+	}
+
+	return results, p.failure(err)
+}
+
+// ListStarsPaginated fetches users in a paginated fashion, see ListStarsPaginationContext for usage.
+func (api *Client) ListStarsPaginated(options ...ListStarsOption) StarredItemPagination {
+	return newStarPagination(api, options...)
+}
+
+func newStarPagination(c *Client, options ...ListStarsOption) (sip StarredItemPagination) {
+	sip = StarredItemPagination{
+		c:     c,
+		limit: 200, // per slack api documentation.
+	}
+
+	for _, opt := range options {
+		opt(&sip)
+	}
+
+	return sip
+}
+
+// done checks if the pagination has completed
+func (StarredItemPagination) done(err error) bool {
+	return err == errPaginationComplete
+}
+
+// done checks if pagination failed.
+func (t StarredItemPagination) failure(err error) error {
+	if t.done(err) {
+		return nil
+	}
+
+	return err
+}
+
+// next gets the next list of starred items based on the cursor value
+func (t StarredItemPagination) next(ctx context.Context) (_ StarredItemPagination, err error) {
+	var (
+		resp *listResponsePaginated
+	)
+
+	if t.c == nil || (t.previousResp != nil && t.previousResp.Cursor == "") {
+		return t, errPaginationComplete
+	}
+
+	t.previousResp = t.previousResp.initialize()
+
+	values := url.Values{
+		"limit":  {strconv.Itoa(t.limit)},
+		"token":  {t.c.token},
+		"cursor": {t.previousResp.Cursor},
+	}
+
+	if err = t.c.postMethod(ctx, "stars.list", values, &resp); err != nil {
+		return t, err
+	}
+
+	t.previousResp = &resp.Metadata
+	t.Items = resp.Items
+
+	return t, nil
+}

backend/vendor/github.com/slack-go/slack/team.go

@@ -0,0 +1,167 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+const (
+	DEFAULT_LOGINS_COUNT = 100
+	DEFAULT_LOGINS_PAGE  = 1
+)
+
+type TeamResponse struct {
+	Team TeamInfo `json:"team"`
+	SlackResponse
+}
+
+type TeamInfo struct {
+	ID          string                 `json:"id"`
+	Name        string                 `json:"name"`
+	Domain      string                 `json:"domain"`
+	EmailDomain string                 `json:"email_domain"`
+	Icon        map[string]interface{} `json:"icon"`
+}
+
+type LoginResponse struct {
+	Logins []Login `json:"logins"`
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+type Login struct {
+	UserID    string `json:"user_id"`
+	Username  string `json:"username"`
+	DateFirst int    `json:"date_first"`
+	DateLast  int    `json:"date_last"`
+	Count     int    `json:"count"`
+	IP        string `json:"ip"`
+	UserAgent string `json:"user_agent"`
+	ISP       string `json:"isp"`
+	Country   string `json:"country"`
+	Region    string `json:"region"`
+}
+
+type BillableInfoResponse struct {
+	BillableInfo map[string]BillingActive `json:"billable_info"`
+	SlackResponse
+}
+
+type BillingActive struct {
+	BillingActive bool `json:"billing_active"`
+}
+
+// AccessLogParameters contains all the parameters necessary (including the optional ones) for a GetAccessLogs() request
+type AccessLogParameters struct {
+	Count int
+	Page  int
+}
+
+// NewAccessLogParameters provides an instance of AccessLogParameters with all the sane default values set
+func NewAccessLogParameters() AccessLogParameters {
+	return AccessLogParameters{
+		Count: DEFAULT_LOGINS_COUNT,
+		Page:  DEFAULT_LOGINS_PAGE,
+	}
+}
+
+func (api *Client) teamRequest(ctx context.Context, path string, values url.Values) (*TeamResponse, error) {
+	response := &TeamResponse{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+func (api *Client) billableInfoRequest(ctx context.Context, path string, values url.Values) (map[string]BillingActive, error) {
+	response := &BillableInfoResponse{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.BillableInfo, response.Err()
+}
+
+func (api *Client) accessLogsRequest(ctx context.Context, path string, values url.Values) (*LoginResponse, error) {
+	response := &LoginResponse{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+	return response, response.Err()
+}
+
+// GetTeamInfo gets the Team Information of the user
+func (api *Client) GetTeamInfo() (*TeamInfo, error) {
+	return api.GetTeamInfoContext(context.Background())
+}
+
+// GetTeamInfoContext gets the Team Information of the user with a custom context
+func (api *Client) GetTeamInfoContext(ctx context.Context) (*TeamInfo, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	response, err := api.teamRequest(ctx, "team.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Team, nil
+}
+
+// GetAccessLogs retrieves a page of logins according to the parameters given
+func (api *Client) GetAccessLogs(params AccessLogParameters) ([]Login, *Paging, error) {
+	return api.GetAccessLogsContext(context.Background(), params)
+}
+
+// GetAccessLogsContext retrieves a page of logins according to the parameters given with a custom context
+func (api *Client) GetAccessLogsContext(ctx context.Context, params AccessLogParameters) ([]Login, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.Count != DEFAULT_LOGINS_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_LOGINS_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+
+	response, err := api.accessLogsRequest(ctx, "team.accessLogs", values)
+	if err != nil {
+		return nil, nil, err
+	}
+	return response.Logins, &response.Paging, nil
+}
+
+// GetBillableInfo ...
+func (api *Client) GetBillableInfo(user string) (map[string]BillingActive, error) {
+	return api.GetBillableInfoContext(context.Background(), user)
+}
+
+// GetBillableInfoContext ...
+func (api *Client) GetBillableInfoContext(ctx context.Context, user string) (map[string]BillingActive, error) {
+	values := url.Values{
+		"token": {api.token},
+		"user":  {user},
+	}
+
+	return api.billableInfoRequest(ctx, "team.billableInfo", values)
+}
+
+// GetBillableInfoForTeam returns the billing_active status of all users on the team.
+func (api *Client) GetBillableInfoForTeam() (map[string]BillingActive, error) {
+	return api.GetBillableInfoForTeamContext(context.Background())
+}
+
+// GetBillableInfoForTeamContext returns the billing_active status of all users on the team with a custom context
+func (api *Client) GetBillableInfoForTeamContext(ctx context.Context) (map[string]BillingActive, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	return api.billableInfoRequest(ctx, "team.billableInfo", values)
+}

backend/vendor/github.com/slack-go/slack/usergroups.go

@@ -0,0 +1,258 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strings"
+)
+
+// UserGroup contains all the information of a user group
+type UserGroup struct {
+	ID          string         `json:"id"`
+	TeamID      string         `json:"team_id"`
+	IsUserGroup bool           `json:"is_usergroup"`
+	Name        string         `json:"name"`
+	Description string         `json:"description"`
+	Handle      string         `json:"handle"`
+	IsExternal  bool           `json:"is_external"`
+	DateCreate  JSONTime       `json:"date_create"`
+	DateUpdate  JSONTime       `json:"date_update"`
+	DateDelete  JSONTime       `json:"date_delete"`
+	AutoType    string         `json:"auto_type"`
+	CreatedBy   string         `json:"created_by"`
+	UpdatedBy   string         `json:"updated_by"`
+	DeletedBy   string         `json:"deleted_by"`
+	Prefs       UserGroupPrefs `json:"prefs"`
+	UserCount   int            `json:"user_count"`
+	Users       []string       `json:"users"`
+}
+
+// UserGroupPrefs contains default channels and groups (private channels)
+type UserGroupPrefs struct {
+	Channels []string `json:"channels"`
+	Groups   []string `json:"groups"`
+}
+
+type userGroupResponseFull struct {
+	UserGroups []UserGroup `json:"usergroups"`
+	UserGroup  UserGroup   `json:"usergroup"`
+	Users      []string    `json:"users"`
+	SlackResponse
+}
+
+func (api *Client) userGroupRequest(ctx context.Context, path string, values url.Values) (*userGroupResponseFull, error) {
+	response := &userGroupResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// CreateUserGroup creates a new user group
+func (api *Client) CreateUserGroup(userGroup UserGroup) (UserGroup, error) {
+	return api.CreateUserGroupContext(context.Background(), userGroup)
+}
+
+// CreateUserGroupContext creates a new user group with a custom context
+func (api *Client) CreateUserGroupContext(ctx context.Context, userGroup UserGroup) (UserGroup, error) {
+	values := url.Values{
+		"token": {api.token},
+		"name":  {userGroup.Name},
+	}
+
+	if userGroup.Handle != "" {
+		values["handle"] = []string{userGroup.Handle}
+	}
+
+	if userGroup.Description != "" {
+		values["description"] = []string{userGroup.Description}
+	}
+
+	if len(userGroup.Prefs.Channels) > 0 {
+		values["channels"] = []string{strings.Join(userGroup.Prefs.Channels, ",")}
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.create", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
+
+// DisableUserGroup disables an existing user group
+func (api *Client) DisableUserGroup(userGroup string) (UserGroup, error) {
+	return api.DisableUserGroupContext(context.Background(), userGroup)
+}
+
+// DisableUserGroupContext disables an existing user group with a custom context
+func (api *Client) DisableUserGroupContext(ctx context.Context, userGroup string) (UserGroup, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup},
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.disable", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
+
+// EnableUserGroup enables an existing user group
+func (api *Client) EnableUserGroup(userGroup string) (UserGroup, error) {
+	return api.EnableUserGroupContext(context.Background(), userGroup)
+}
+
+// EnableUserGroupContext enables an existing user group with a custom context
+func (api *Client) EnableUserGroupContext(ctx context.Context, userGroup string) (UserGroup, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup},
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.enable", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
+
+// GetUserGroupsOption options for the GetUserGroups method call.
+type GetUserGroupsOption func(*GetUserGroupsParams)
+
+// GetUserGroupsOptionIncludeCount include the number of users in each User Group (default: false)
+func GetUserGroupsOptionIncludeCount(b bool) GetUserGroupsOption {
+	return func(params *GetUserGroupsParams) {
+		params.IncludeCount = b
+	}
+}
+
+// GetUserGroupsOptionIncludeDisabled include disabled User Groups (default: false)
+func GetUserGroupsOptionIncludeDisabled(b bool) GetUserGroupsOption {
+	return func(params *GetUserGroupsParams) {
+		params.IncludeDisabled = b
+	}
+}
+
+// GetUserGroupsOptionIncludeUsers include the list of users for each User Group (default: false)
+func GetUserGroupsOptionIncludeUsers(b bool) GetUserGroupsOption {
+	return func(params *GetUserGroupsParams) {
+		params.IncludeUsers = b
+	}
+}
+
+// GetUserGroupsParams contains arguments for GetUserGroups method call
+type GetUserGroupsParams struct {
+	IncludeCount    bool
+	IncludeDisabled bool
+	IncludeUsers    bool
+}
+
+// GetUserGroups returns a list of user groups for the team
+func (api *Client) GetUserGroups(options ...GetUserGroupsOption) ([]UserGroup, error) {
+	return api.GetUserGroupsContext(context.Background(), options...)
+}
+
+// GetUserGroupsContext returns a list of user groups for the team with a custom context
+func (api *Client) GetUserGroupsContext(ctx context.Context, options ...GetUserGroupsOption) ([]UserGroup, error) {
+	params := GetUserGroupsParams{}
+
+	for _, opt := range options {
+		opt(&params)
+	}
+
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.IncludeCount {
+		values.Add("include_count", "true")
+	}
+	if params.IncludeDisabled {
+		values.Add("include_disabled", "true")
+	}
+	if params.IncludeUsers {
+		values.Add("include_users", "true")
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.list", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.UserGroups, nil
+}
+
+// UpdateUserGroup will update an existing user group
+func (api *Client) UpdateUserGroup(userGroup UserGroup) (UserGroup, error) {
+	return api.UpdateUserGroupContext(context.Background(), userGroup)
+}
+
+// UpdateUserGroupContext will update an existing user group with a custom context
+func (api *Client) UpdateUserGroupContext(ctx context.Context, userGroup UserGroup) (UserGroup, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup.ID},
+	}
+
+	if userGroup.Name != "" {
+		values["name"] = []string{userGroup.Name}
+	}
+
+	if userGroup.Handle != "" {
+		values["handle"] = []string{userGroup.Handle}
+	}
+
+	if userGroup.Description != "" {
+		values["description"] = []string{userGroup.Description}
+	}
+
+	if len(userGroup.Prefs.Channels) > 0 {
+		values["channels"] = []string{strings.Join(userGroup.Prefs.Channels, ",")}
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.update", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
+
+// GetUserGroupMembers will retrieve the current list of users in a group
+func (api *Client) GetUserGroupMembers(userGroup string) ([]string, error) {
+	return api.GetUserGroupMembersContext(context.Background(), userGroup)
+}
+
+// GetUserGroupMembersContext will retrieve the current list of users in a group with a custom context
+func (api *Client) GetUserGroupMembersContext(ctx context.Context, userGroup string) ([]string, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup},
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.users.list", values)
+	if err != nil {
+		return []string{}, err
+	}
+	return response.Users, nil
+}
+
+// UpdateUserGroupMembers will update the members of an existing user group
+func (api *Client) UpdateUserGroupMembers(userGroup string, members string) (UserGroup, error) {
+	return api.UpdateUserGroupMembersContext(context.Background(), userGroup, members)
+}
+
+// UpdateUserGroupMembersContext will update the members of an existing user group with a custom context
+func (api *Client) UpdateUserGroupMembersContext(ctx context.Context, userGroup string, members string) (UserGroup, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup},
+		"users":     {members},
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.users.update", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}

backend/vendor/github.com/slack-go/slack/users.go

@@ -0,0 +1,666 @@
+package slack
+
+import (
+	"context"
+	"encoding/json"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	DEFAULT_USER_PHOTO_CROP_X = -1
+	DEFAULT_USER_PHOTO_CROP_Y = -1
+	DEFAULT_USER_PHOTO_CROP_W = -1
+)
+
+// UserProfile contains all the information details of a given user
+type UserProfile struct {
+	FirstName             string                  `json:"first_name"`
+	LastName              string                  `json:"last_name"`
+	RealName              string                  `json:"real_name"`
+	RealNameNormalized    string                  `json:"real_name_normalized"`
+	DisplayName           string                  `json:"display_name"`
+	DisplayNameNormalized string                  `json:"display_name_normalized"`
+	Email                 string                  `json:"email"`
+	Skype                 string                  `json:"skype"`
+	Phone                 string                  `json:"phone"`
+	Image24               string                  `json:"image_24"`
+	Image32               string                  `json:"image_32"`
+	Image48               string                  `json:"image_48"`
+	Image72               string                  `json:"image_72"`
+	Image192              string                  `json:"image_192"`
+	Image512              string                  `json:"image_512"`
+	ImageOriginal         string                  `json:"image_original"`
+	Title                 string                  `json:"title"`
+	BotID                 string                  `json:"bot_id,omitempty"`
+	ApiAppID              string                  `json:"api_app_id,omitempty"`
+	StatusText            string                  `json:"status_text,omitempty"`
+	StatusEmoji           string                  `json:"status_emoji,omitempty"`
+	StatusExpiration      int                     `json:"status_expiration"`
+	Team                  string                  `json:"team"`
+	Fields                UserProfileCustomFields `json:"fields"`
+}
+
+// UserProfileCustomFields represents user profile's custom fields.
+// Slack API's response data type is inconsistent so we use the struct.
+// For detail, please see below.
+// https://github.com/slack-go/slack/pull/298#discussion_r185159233
+type UserProfileCustomFields struct {
+	fields map[string]UserProfileCustomField
+}
+
+// UnmarshalJSON is the implementation of the json.Unmarshaler interface.
+func (fields *UserProfileCustomFields) UnmarshalJSON(b []byte) error {
+	// https://github.com/slack-go/slack/pull/298#discussion_r185159233
+	if string(b) == "[]" {
+		return nil
+	}
+	return json.Unmarshal(b, &fields.fields)
+}
+
+// MarshalJSON is the implementation of the json.Marshaler interface.
+func (fields UserProfileCustomFields) MarshalJSON() ([]byte, error) {
+	if len(fields.fields) == 0 {
+		return []byte("[]"), nil
+	}
+	return json.Marshal(fields.fields)
+}
+
+// ToMap returns a map of custom fields.
+func (fields *UserProfileCustomFields) ToMap() map[string]UserProfileCustomField {
+	return fields.fields
+}
+
+// Len returns the number of custom fields.
+func (fields *UserProfileCustomFields) Len() int {
+	return len(fields.fields)
+}
+
+// SetMap sets a map of custom fields.
+func (fields *UserProfileCustomFields) SetMap(m map[string]UserProfileCustomField) {
+	fields.fields = m
+}
+
+// FieldsMap returns a map of custom fields.
+func (profile *UserProfile) FieldsMap() map[string]UserProfileCustomField {
+	return profile.Fields.ToMap()
+}
+
+// SetFieldsMap sets a map of custom fields.
+func (profile *UserProfile) SetFieldsMap(m map[string]UserProfileCustomField) {
+	profile.Fields.SetMap(m)
+}
+
+// UserProfileCustomField represents a custom user profile field
+type UserProfileCustomField struct {
+	Value string `json:"value"`
+	Alt   string `json:"alt"`
+	Label string `json:"label"`
+}
+
+// User contains all the information of a user
+type User struct {
+	ID                string         `json:"id"`
+	TeamID            string         `json:"team_id"`
+	Name              string         `json:"name"`
+	Deleted           bool           `json:"deleted"`
+	Color             string         `json:"color"`
+	RealName          string         `json:"real_name"`
+	TZ                string         `json:"tz,omitempty"`
+	TZLabel           string         `json:"tz_label"`
+	TZOffset          int            `json:"tz_offset"`
+	Profile           UserProfile    `json:"profile"`
+	IsBot             bool           `json:"is_bot"`
+	IsAdmin           bool           `json:"is_admin"`
+	IsOwner           bool           `json:"is_owner"`
+	IsPrimaryOwner    bool           `json:"is_primary_owner"`
+	IsRestricted      bool           `json:"is_restricted"`
+	IsUltraRestricted bool           `json:"is_ultra_restricted"`
+	IsStranger        bool           `json:"is_stranger"`
+	IsAppUser         bool           `json:"is_app_user"`
+	IsInvitedUser     bool           `json:"is_invited_user"`
+	Has2FA            bool           `json:"has_2fa"`
+	HasFiles          bool           `json:"has_files"`
+	Presence          string         `json:"presence"`
+	Locale            string         `json:"locale"`
+	Updated           JSONTime       `json:"updated"`
+	Enterprise        EnterpriseUser `json:"enterprise_user,omitempty"`
+}
+
+// UserPresence contains details about a user online status
+type UserPresence struct {
+	Presence        string   `json:"presence,omitempty"`
+	Online          bool     `json:"online,omitempty"`
+	AutoAway        bool     `json:"auto_away,omitempty"`
+	ManualAway      bool     `json:"manual_away,omitempty"`
+	ConnectionCount int      `json:"connection_count,omitempty"`
+	LastActivity    JSONTime `json:"last_activity,omitempty"`
+}
+
+type UserIdentityResponse struct {
+	User UserIdentity `json:"user"`
+	Team TeamIdentity `json:"team"`
+	SlackResponse
+}
+
+type UserIdentity struct {
+	ID       string `json:"id"`
+	Name     string `json:"name"`
+	Email    string `json:"email"`
+	Image24  string `json:"image_24"`
+	Image32  string `json:"image_32"`
+	Image48  string `json:"image_48"`
+	Image72  string `json:"image_72"`
+	Image192 string `json:"image_192"`
+	Image512 string `json:"image_512"`
+}
+
+// EnterpriseUser is present when a user is part of Slack Enterprise Grid
+// https://api.slack.com/types/user#enterprise_grid_user_objects
+type EnterpriseUser struct {
+	ID             string   `json:"id"`
+	EnterpriseID   string   `json:"enterprise_id"`
+	EnterpriseName string   `json:"enterprise_name"`
+	IsAdmin        bool     `json:"is_admin"`
+	IsOwner        bool     `json:"is_owner"`
+	Teams          []string `json:"teams"`
+}
+
+type TeamIdentity struct {
+	ID            string `json:"id"`
+	Name          string `json:"name"`
+	Domain        string `json:"domain"`
+	Image34       string `json:"image_34"`
+	Image44       string `json:"image_44"`
+	Image68       string `json:"image_68"`
+	Image88       string `json:"image_88"`
+	Image102      string `json:"image_102"`
+	Image132      string `json:"image_132"`
+	Image230      string `json:"image_230"`
+	ImageDefault  bool   `json:"image_default"`
+	ImageOriginal string `json:"image_original"`
+}
+
+type userResponseFull struct {
+	Members []User `json:"members,omitempty"`
+	User    `json:"user,omitempty"`
+	Users   []User `json:"users,omitempty"`
+	UserPresence
+	SlackResponse
+	Metadata ResponseMetadata `json:"response_metadata"`
+}
+
+type UserSetPhotoParams struct {
+	CropX int
+	CropY int
+	CropW int
+}
+
+func NewUserSetPhotoParams() UserSetPhotoParams {
+	return UserSetPhotoParams{
+		CropX: DEFAULT_USER_PHOTO_CROP_X,
+		CropY: DEFAULT_USER_PHOTO_CROP_Y,
+		CropW: DEFAULT_USER_PHOTO_CROP_W,
+	}
+}
+
+func (api *Client) userRequest(ctx context.Context, path string, values url.Values) (*userResponseFull, error) {
+	response := &userResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// GetUserPresence will retrieve the current presence status of given user.
+func (api *Client) GetUserPresence(user string) (*UserPresence, error) {
+	return api.GetUserPresenceContext(context.Background(), user)
+}
+
+// GetUserPresenceContext will retrieve the current presence status of given user with a custom context.
+func (api *Client) GetUserPresenceContext(ctx context.Context, user string) (*UserPresence, error) {
+	values := url.Values{
+		"token": {api.token},
+		"user":  {user},
+	}
+
+	response, err := api.userRequest(ctx, "users.getPresence", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.UserPresence, nil
+}
+
+// GetUserInfo will retrieve the complete user information
+func (api *Client) GetUserInfo(user string) (*User, error) {
+	return api.GetUserInfoContext(context.Background(), user)
+}
+
+// GetUserInfoContext will retrieve the complete user information with a custom context
+func (api *Client) GetUserInfoContext(ctx context.Context, user string) (*User, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"user":           {user},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	response, err := api.userRequest(ctx, "users.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.User, nil
+}
+
+// GetUsersInfo will retrieve the complete multi-users information
+func (api *Client) GetUsersInfo(users ...string) (*[]User, error) {
+	return api.GetUsersInfoContext(context.Background(), users...)
+}
+
+// GetUsersInfoContext will retrieve the complete multi-users information with a custom context
+func (api *Client) GetUsersInfoContext(ctx context.Context, users ...string) (*[]User, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"users":          {strings.Join(users, ",")},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	response, err := api.userRequest(ctx, "users.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Users, nil
+}
+
+// GetUsersOption options for the GetUsers method call.
+type GetUsersOption func(*UserPagination)
+
+// GetUsersOptionLimit limit the number of users returned
+func GetUsersOptionLimit(n int) GetUsersOption {
+	return func(p *UserPagination) {
+		p.limit = n
+	}
+}
+
+// GetUsersOptionPresence include user presence
+func GetUsersOptionPresence(n bool) GetUsersOption {
+	return func(p *UserPagination) {
+		p.presence = n
+	}
+}
+
+func newUserPagination(c *Client, options ...GetUsersOption) (up UserPagination) {
+	up = UserPagination{
+		c:     c,
+		limit: 200, // per slack api documentation.
+	}
+
+	for _, opt := range options {
+		opt(&up)
+	}
+
+	return up
+}
+
+// UserPagination allows for paginating over the users
+type UserPagination struct {
+	Users        []User
+	limit        int
+	presence     bool
+	previousResp *ResponseMetadata
+	c            *Client
+}
+
+// Done checks if the pagination has completed
+func (UserPagination) Done(err error) bool {
+	return err == errPaginationComplete
+}
+
+// Failure checks if pagination failed.
+func (t UserPagination) Failure(err error) error {
+	if t.Done(err) {
+		return nil
+	}
+
+	return err
+}
+
+func (t UserPagination) Next(ctx context.Context) (_ UserPagination, err error) {
+	var (
+		resp *userResponseFull
+	)
+
+	if t.c == nil || (t.previousResp != nil && t.previousResp.Cursor == "") {
+		return t, errPaginationComplete
+	}
+
+	t.previousResp = t.previousResp.initialize()
+
+	values := url.Values{
+		"limit":          {strconv.Itoa(t.limit)},
+		"presence":       {strconv.FormatBool(t.presence)},
+		"token":          {t.c.token},
+		"cursor":         {t.previousResp.Cursor},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	if resp, err = t.c.userRequest(ctx, "users.list", values); err != nil {
+		return t, err
+	}
+
+	t.c.Debugf("GetUsersContext: got %d users; metadata %v", len(resp.Members), resp.Metadata)
+	t.Users = resp.Members
+	t.previousResp = &resp.Metadata
+
+	return t, nil
+}
+
+// GetUsersPaginated fetches users in a paginated fashion, see GetUsersContext for usage.
+func (api *Client) GetUsersPaginated(options ...GetUsersOption) UserPagination {
+	return newUserPagination(api, options...)
+}
+
+// GetUsers returns the list of users (with their detailed information)
+func (api *Client) GetUsers() ([]User, error) {
+	return api.GetUsersContext(context.Background())
+}
+
+// GetUsersContext returns the list of users (with their detailed information) with a custom context
+func (api *Client) GetUsersContext(ctx context.Context) (results []User, err error) {
+	p := api.GetUsersPaginated()
+	for err == nil {
+		p, err = p.Next(ctx)
+		if err == nil {
+			results = append(results, p.Users...)
+		} else if rateLimitedError, ok := err.(*RateLimitedError); ok {
+			select {
+			case <-ctx.Done():
+				err = ctx.Err()
+			case <-time.After(rateLimitedError.RetryAfter):
+				err = nil
+			}
+		}
+	}
+
+	return results, p.Failure(err)
+}
+
+// GetUserByEmail will retrieve the complete user information by email
+func (api *Client) GetUserByEmail(email string) (*User, error) {
+	return api.GetUserByEmailContext(context.Background(), email)
+}
+
+// GetUserByEmailContext will retrieve the complete user information by email with a custom context
+func (api *Client) GetUserByEmailContext(ctx context.Context, email string) (*User, error) {
+	values := url.Values{
+		"token": {api.token},
+		"email": {email},
+	}
+	response, err := api.userRequest(ctx, "users.lookupByEmail", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.User, nil
+}
+
+// SetUserAsActive marks the currently authenticated user as active
+func (api *Client) SetUserAsActive() error {
+	return api.SetUserAsActiveContext(context.Background())
+}
+
+// SetUserAsActiveContext marks the currently authenticated user as active with a custom context
+func (api *Client) SetUserAsActiveContext(ctx context.Context) (err error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	_, err = api.userRequest(ctx, "users.setActive", values)
+	return err
+}
+
+// SetUserPresence changes the currently authenticated user presence
+func (api *Client) SetUserPresence(presence string) error {
+	return api.SetUserPresenceContext(context.Background(), presence)
+}
+
+// SetUserPresenceContext changes the currently authenticated user presence with a custom context
+func (api *Client) SetUserPresenceContext(ctx context.Context, presence string) error {
+	values := url.Values{
+		"token":    {api.token},
+		"presence": {presence},
+	}
+
+	_, err := api.userRequest(ctx, "users.setPresence", values)
+	return err
+}
+
+// GetUserIdentity will retrieve user info available per identity scopes
+func (api *Client) GetUserIdentity() (*UserIdentityResponse, error) {
+	return api.GetUserIdentityContext(context.Background())
+}
+
+// GetUserIdentityContext will retrieve user info available per identity scopes with a custom context
+func (api *Client) GetUserIdentityContext(ctx context.Context) (response *UserIdentityResponse, err error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	response = &UserIdentityResponse{}
+
+	err = api.postMethod(ctx, "users.identity", values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}
+
+// SetUserPhoto changes the currently authenticated user's profile image
+func (api *Client) SetUserPhoto(image string, params UserSetPhotoParams) error {
+	return api.SetUserPhotoContext(context.Background(), image, params)
+}
+
+// SetUserPhotoContext changes the currently authenticated user's profile image using a custom context
+func (api *Client) SetUserPhotoContext(ctx context.Context, image string, params UserSetPhotoParams) (err error) {
+	response := &SlackResponse{}
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.CropX != DEFAULT_USER_PHOTO_CROP_X {
+		values.Add("crop_x", strconv.Itoa(params.CropX))
+	}
+	if params.CropY != DEFAULT_USER_PHOTO_CROP_Y {
+		values.Add("crop_y", strconv.Itoa(params.CropX))
+	}
+	if params.CropW != DEFAULT_USER_PHOTO_CROP_W {
+		values.Add("crop_w", strconv.Itoa(params.CropW))
+	}
+
+	err = postLocalWithMultipartResponse(ctx, api.httpclient, api.endpoint+"users.setPhoto", image, "image", values, response, api)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// DeleteUserPhoto deletes the current authenticated user's profile image
+func (api *Client) DeleteUserPhoto() error {
+	return api.DeleteUserPhotoContext(context.Background())
+}
+
+// DeleteUserPhotoContext deletes the current authenticated user's profile image with a custom context
+func (api *Client) DeleteUserPhotoContext(ctx context.Context) (err error) {
+	response := &SlackResponse{}
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	err = api.postMethod(ctx, "users.deletePhoto", values, response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// SetUserRealName changes the currently authenticated user's realName
+//
+// For more information see SetUserRealNameContextWithUser
+func (api *Client) SetUserRealName(realName string) error {
+	return api.SetUserRealNameContextWithUser(context.Background(), "", realName)
+}
+
+// SetUserRealNameContextWithUser will set a real name for the provided user with a custom context
+func (api *Client) SetUserRealNameContextWithUser(ctx context.Context, user, realName string) error {
+	profile, err := json.Marshal(
+		&struct {
+			RealName string `json:"real_name"`
+		}{
+			RealName: realName,
+		},
+	)
+
+	if err != nil {
+		return err
+	}
+
+	values := url.Values{
+		"token":   {api.token},
+		"profile": {string(profile)},
+	}
+
+	// optional field. It should not be set if empty
+	if user != "" {
+		values["user"] = []string{user}
+	}
+
+	response := &userResponseFull{}
+	if err = api.postMethod(ctx, "users.profile.set", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// SetUserCustomStatus will set a custom status and emoji for the currently
+// authenticated user. If statusEmoji is "" and statusText is not, the Slack API
+// will automatically set it to ":speech_balloon:". Otherwise, if both are ""
+// the Slack API will unset the custom status/emoji. If statusExpiration is set to 0
+// the status will not expire.
+func (api *Client) SetUserCustomStatus(statusText, statusEmoji string, statusExpiration int64) error {
+	return api.SetUserCustomStatusContextWithUser(context.Background(), "", statusText, statusEmoji, statusExpiration)
+}
+
+// SetUserCustomStatusContext will set a custom status and emoji for the currently authenticated user with a custom context
+//
+// For more information see SetUserCustomStatus
+func (api *Client) SetUserCustomStatusContext(ctx context.Context, statusText, statusEmoji string, statusExpiration int64) error {
+	return api.SetUserCustomStatusContextWithUser(ctx, "", statusText, statusEmoji, statusExpiration)
+}
+
+// SetUserCustomStatusWithUser will set a custom status and emoji for the provided user.
+//
+// For more information see SetUserCustomStatus
+func (api *Client) SetUserCustomStatusWithUser(user, statusText, statusEmoji string, statusExpiration int64) error {
+	return api.SetUserCustomStatusContextWithUser(context.Background(), user, statusText, statusEmoji, statusExpiration)
+}
+
+// SetUserCustomStatusContextWithUser will set a custom status and emoji for the provided user with a custom context
+//
+// For more information see SetUserCustomStatus
+func (api *Client) SetUserCustomStatusContextWithUser(ctx context.Context, user, statusText, statusEmoji string, statusExpiration int64) error {
+	// XXX(theckman): this anonymous struct is for making requests to the Slack
+	// API for setting and unsetting a User's Custom Status/Emoji. To change
+	// these values we must provide a JSON document as the profile POST field.
+	//
+	// We use an anonymous struct over UserProfile because to unset the values
+	// on the User's profile we cannot use the `json:"omitempty"` tag. This is
+	// because an empty string ("") is what's used to unset the values. Check
+	// out the API docs for more details:
+	//
+	// - https://api.slack.com/docs/presence-and-status#custom_status
+	profile, err := json.Marshal(
+		&struct {
+			StatusText       string `json:"status_text"`
+			StatusEmoji      string `json:"status_emoji"`
+			StatusExpiration int64  `json:"status_expiration"`
+		}{
+			StatusText:       statusText,
+			StatusEmoji:      statusEmoji,
+			StatusExpiration: statusExpiration,
+		},
+	)
+
+	if err != nil {
+		return err
+	}
+
+	values := url.Values{
+		"token":   {api.token},
+		"profile": {string(profile)},
+	}
+
+	// optional field. It should not be set if empty
+	if user != "" {
+		values["user"] = []string{user}
+	}
+
+	response := &userResponseFull{}
+	if err = api.postMethod(ctx, "users.profile.set", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// UnsetUserCustomStatus removes the custom status message for the currently
+// authenticated user. This is a convenience method that wraps (*Client).SetUserCustomStatus().
+func (api *Client) UnsetUserCustomStatus() error {
+	return api.UnsetUserCustomStatusContext(context.Background())
+}
+
+// UnsetUserCustomStatusContext removes the custom status message for the currently authenticated user
+// with a custom context. This is a convenience method that wraps (*Client).SetUserCustomStatus().
+func (api *Client) UnsetUserCustomStatusContext(ctx context.Context) error {
+	return api.SetUserCustomStatusContext(ctx, "", "", 0)
+}
+
+// GetUserProfile retrieves a user's profile information.
+func (api *Client) GetUserProfile(userID string, includeLabels bool) (*UserProfile, error) {
+	return api.GetUserProfileContext(context.Background(), userID, includeLabels)
+}
+
+type getUserProfileResponse struct {
+	SlackResponse
+	Profile *UserProfile `json:"profile"`
+}
+
+// GetUserProfileContext retrieves a user's profile information with a context.
+func (api *Client) GetUserProfileContext(ctx context.Context, userID string, includeLabels bool) (*UserProfile, error) {
+	values := url.Values{"token": {api.token}}
+	if includeLabels {
+		values.Add("include_labels", "true")
+	}
+	if userID != "" {
+		values.Add("user", userID)
+	}
+	resp := &getUserProfileResponse{}
+
+	err := api.postMethod(ctx, "users.profile.get", values, &resp)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := resp.Err(); err != nil {
+		return nil, err
+	}
+
+	return resp.Profile, nil
+}