remark42/backend/app/store/comment.go

package store

import (
	"html/template"
	"net/url"
	"regexp"
	"strings"
	"time"

	"github.com/PuerkitoBio/goquery"
	"github.com/microcosm-cc/bluemonday"
)

// Comment represents a single comment with optional reference to its parent
type Comment struct {
	ID        string          `json:"id" bson:"_id"`
	ParentID  string          `json:"pid"`
	Text      string          `json:"text"`
	Orig      string          `json:"orig,omitempty"`
	User      User            `json:"user"`
	Locator   Locator         `json:"locator"`
	Score     int             `json:"score"`
	Votes     map[string]bool `json:"votes"`
	Timestamp time.Time       `json:"time" bson:"time"`
	Edit      *Edit           `json:"edit,omitempty" bson:"edit,omitempty"` // pointer to have empty default in json response
	Pin       bool            `json:"pin,omitempty" bson:"pin,omitempty"`
	Deleted   bool            `json:"delete,omitempty" bson:"delete"`
}

// Locator keeps site and url of the post
type Locator struct {
	SiteID string `json:"site,omitempty" bson:"site"`
	URL    string `json:"url"`
}

// Edit indication
type Edit struct {
	Timestamp time.Time `json:"time" bson:"time"`
	Summary   string    `json:"summary"`
}

// PostInfo holds summary for given post url
type PostInfo struct {
	URL      string    `json:"url"`
	Count    int       `json:"count"`
	ReadOnly bool      `json:"read_only,omitempty" bson:"read_only,omitempty"`
	FirstTS  time.Time `json:"first_time,omitempty" bson:"first_time,omitempty"`
	LastTS   time.Time `json:"last_time,omitempty" bson:"last_time,omitempty"`
}

// BlockedUser holds id and ts for blocked user
type BlockedUser struct {
	ID    string    `json:"id"`
	Name  string    `json:"name"`
	Until time.Time `json:"time"`
}

// DeleteMode defines how much comment info will be erased
type DeleteMode int

// DeleteMode enum
const (
	SoftDelete DeleteMode = 0
	HardDelete DeleteMode = 1
)

// Maximum length for URL text shortening.
const shortURLLen = 48

// PrepareUntrusted pre-processes a comment received from untrusted source by clearing all
// autogen fields and reset everything users not supposed to provide
func (c *Comment) PrepareUntrusted() {
	c.ID = ""                 // don't allow user to define ID, force auto-gen
	c.Timestamp = time.Time{} // reset time, force auto-gen
	c.Votes = make(map[string]bool)
	c.Score = 0
	c.Edit = nil
	c.Pin = false
	c.Deleted = false
}

// SetDeleted clears comment info, reset to deleted state. hard flag will clear all user info as well
func (c *Comment) SetDeleted(mode DeleteMode) {
	c.Text = ""
	c.Orig = ""
	c.Score = 0
	c.Votes = map[string]bool{}
	c.Edit = nil
	c.Deleted = true
	c.Pin = false

	if mode == HardDelete {
		c.User.Name = "deleted"
		c.User.ID = "deleted"
		c.User.Picture = ""
		c.User.IP = ""
	}
}

// Sanitize clean dangerous html/js from the comment, shorten autolinks.
func (c *Comment) Sanitize() {
	p := bluemonday.UGCPolicy()
	p.AllowAttrs("class").Matching(regexp.MustCompile("^language-[a-zA-Z0-9]+$")).OnElements("code")
	c.Text = p.Sanitize(c.Text)
	c.Text = shortenAutoLinks(c.Text, shortURLLen)
	c.Orig = p.Sanitize(c.Orig)
	c.User.ID = template.HTMLEscapeString(c.User.ID)
	c.User.Name = template.HTMLEscapeString(c.User.Name)
	c.User.Picture = p.Sanitize(c.User.Picture)
}

// Shortens all the automatic links in HTML: auto link has equal "href" and "text" attributes.
func shortenAutoLinks(commentHTML string, max int) (resHTML string) {
	doc, err := goquery.NewDocumentFromReader(strings.NewReader(commentHTML))
	if err != nil {
		return commentHTML
	}
	doc.Find("a").Each(func(i int, s *goquery.Selection) {
		if href, ok := s.Attr("href"); ok {
			if href != s.Text() || len(href) < max+3 || max < 3 {
				return
			}
			url, e := url.Parse(href)
			if e != nil {
				return
			}
			url.Path, url.RawQuery, url.Fragment = "", "", ""
			host := url.String()
			if host == "" {
				return
			}
			short := href[:max-3]
			if len(short) < len(host) {
				short = host
			}
			s.SetText(short + "...")
		}
	})
	resHTML, err = doc.Find("body").Html()
	if err != nil {
		return commentHTML
	}
	return resHTML
}