initial notifier with nop implementation

README.md

@@ -206,6 +206,7 @@ Sort can be `time` or `score`. Supported sort order with prefix -/+, i.e. `-time
         Auth         []string `json:"auth_providers"`
     }
     ```
+- `PUT /api/v1/notify?site=site-id&url=post-url&action=1` - subscribe(action=1)/unsubscribe(0) comment notifications. _auth required_
 
 ### Admin
 

app/main.go

@@ -7,6 +7,8 @@ import (
 	"os"
 	"time"
 
+	"github.com/umputun/remark/app/notifier"
+
 	"github.com/gorilla/sessions"
 	"github.com/hashicorp/logutils"
 	"github.com/jessevdk/go-flags"
@@ -114,6 +116,7 @@ func main() {
 		AuthProviders: makeAuthProviders(sessionStore, avatarProxy),
 		Cache:         common.NewLoadingCache(4*time.Hour, 15*time.Minute, postFlushFn),
 		AvatarProxy:   avatarProxy,
+		Notifier:      notifier.NoOperation{},
 	}
 
 	if opts.DevMode {

app/notifier/notifier.go

@@ -0,0 +1,35 @@
+package notifier
+
+import (
+	"log"
+
+	"github.com/umputun/remark/app/store"
+)
+
+// Interface defines notifier, sending messages triggered by topic/reply updates
+type Interface interface {
+	Subscribe(locator store.Locator, user store.User) error
+	UnSubscribe(locator store.Locator, user store.User) error
+	OnUpdate(locator store.Locator) error
+}
+
+// NoOperation implements Interface doing nothing but logging
+type NoOperation struct{}
+
+// Subscribe is a fake, just loging attempt
+func (n NoOperation) Subscribe(locator store.Locator, user store.User) error {
+	log.Printf("[DEBUG] user %+v subscribed to %+v", user, locator)
+	return nil
+}
+
+// UnSubscribe is a fake, just loging attempt
+func (n NoOperation) UnSubscribe(locator store.Locator, user store.User) error {
+	log.Printf("[DEBUG] user %+v unsubscribed from %+v", user, locator)
+	return nil
+}
+
+// OnUpdate is a fake, just loging event
+func (n NoOperation) OnUpdate(locator store.Locator) error {
+	log.Printf("[DEBUG] update for %+v", locator)
+	return nil
+}

app/rest/server.go

@@ -22,6 +22,7 @@ import (
 	"gopkg.in/russross/blackfriday.v2"
 
 	"github.com/umputun/remark/app/migrator"
+	"github.com/umputun/remark/app/notifier"
 	"github.com/umputun/remark/app/rest/auth"
 	"github.com/umputun/remark/app/rest/avatar"
 	"github.com/umputun/remark/app/rest/common"
@@ -38,8 +39,10 @@ type Server struct {
 	SessionStore  sessions.Store
 	Exporter      migrator.Exporter
 	Cache         common.LoadingCache
-	DevMode       bool
 	AvatarProxy   *avatar.Proxy
+	Notifier      notifier.Interface
+
+	DevMode bool
 
 	httpServer *http.Server
 	mod        admin
@@ -104,7 +107,7 @@ func (s *Server) Run(port int) {
 			rauth.Put("/comment/{id}", s.updateCommentCtrl)
 			rauth.Get("/user", s.userInfoCtrl)
 			rauth.Put("/vote/{id}", s.voteCtrl)
-
+			rauth.Put("/notify", s.notifyCtrl)
 			// admin routes, admin users only
 			s.mod = admin{dataService: s.DataService, exporter: s.Exporter, cache: s.Cache}
 			rauth.Mount("/admin", s.mod.routes())
@@ -167,8 +170,11 @@ func (s *Server) createCommentCtrl(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	s.Cache.Flush() // reset all caches
+	if err = s.Notifier.OnUpdate(comment.Locator); err != nil {
+		log.Printf("[WARN] can't send notify event for %+v, %s", comment.Locator, err)
+	}
 
+	s.Cache.Flush() // reset all caches
 	render.Status(r, http.StatusCreated)
 	render.JSON(w, r, JSON{"id": id, "locator": comment.Locator})
 }
@@ -410,6 +416,27 @@ func (s *Server) voteCtrl(w http.ResponseWriter, r *http.Request) {
 	render.JSON(w, r, JSON{"id": comment.ID, "score": comment.Score})
 }
 
+// PUT /notify?site=siteID&url=post-url&action=1 - subscribe/unsubscribe to notification
+func (s *Server) notifyCtrl(w http.ResponseWriter, r *http.Request) {
+	user, err := common.GetUserInfo(r)
+	if err != nil {
+		common.SendErrorJSON(w, r, http.StatusUnauthorized, err, "can't get user info")
+		return
+	}
+	locator := store.Locator{SiteID: r.URL.Query().Get("site"), URL: r.URL.Query().Get("url")}
+	action := r.URL.Query().Get("action")
+	switch action {
+	case "1":
+		err = s.Notifier.Subscribe(locator, user)
+	case "0":
+		err = s.Notifier.UnSubscribe(locator, user)
+	}
+	if err != nil {
+		common.SendErrorJSON(w, r, http.StatusBadRequest, err, "can't subscribe/unsubscribe for notifications")
+		return
+	}
+}
+
 // serves static files from /web
 func (s *Server) addFileServer(r chi.Router, path string, root http.FileSystem) {
 	log.Printf("[INFO] run file server for %s", root)