[WIP] Reactions

Only XMPP<->Discord at the moment.

Author: kousu

bridge/config/config.go

@@ -30,6 +30,7 @@ const (
 	EventUserTyping        = "user_typing"
 	EventGetChannelMembers = "get_channel_members"
 	EventNoticeIRC         = "notice_irc"
+	EventReaction          = "reaction"
 )
 
 const ParentIDNotFound = "msg-parent-not-found"
@@ -46,6 +47,7 @@ type Message struct {
 	Gateway    string    `json:"gateway"`
 	ParentID   string    `json:"parent_id"`
 	ParentText string    `json:"parent_text"`
+	Reactions  []string  `json:"reactions"`
 	Timestamp  time.Time `json:"timestamp"`
 	ID         string    `json:"id"`
 	Extra      map[string][]interface{}

bridge/discord/discord.go

@@ -226,6 +226,7 @@ func (b *Bdiscord) Connect() error {
 	b.c.AddHandler(b.messageCreate)
 	b.c.AddHandler(b.messageTyping)
 	b.c.AddHandler(b.messageUpdate)
+	b.c.AddHandler(b.messageReaction)
 	b.c.AddHandler(b.messageDelete)
 	b.c.AddHandler(b.messageDeleteBulk)
 	b.c.AddHandler(b.memberAdd)
@@ -278,7 +279,7 @@ func (b *Bdiscord) Send(msg config.Message) (string, error) {
 
 	// Use webhook to send the message
 	useWebhooks := b.shouldMessageUseWebhooks(&msg)
-	if useWebhooks && msg.Event != config.EventMsgDelete && msg.ParentID == "" {
+	if useWebhooks && msg.Event != config.EventReaction && msg.Event != config.EventMsgDelete && msg.ParentID == "" {
 		return b.handleEventWebhook(&msg, channelID)
 	}
 
@@ -289,6 +290,22 @@ func (b *Bdiscord) Send(msg config.Message) (string, error) {
 func (b *Bdiscord) handleEventBotUser(msg *config.Message, channelID string) (string, error) {
 	b.Log.Debugf("Broadcasting using token (API)")
 
+	if msg.Event == config.EventReaction {
+		// this is a reaction, not a message
+		b.Log.Debugf("Sending reactions: %#v", msg.Reactions)
+		for _, reaction := range msg.Reactions {
+			// TODO: should we verify that reaction is, in fact, a single emoji?
+			// Also: Discord has server-private emojis named like "hello:1234567654321"; can these be bridged in some generic way?
+			b.Log.Debugf("MessageReactionAdd(%#v, %#v, %#v)", channelID, msg.ParentID, reaction)
+			err := b.c.MessageReactionAdd(channelID, msg.ParentID, reaction)
+			if err != nil {
+				return "", err
+			}
+		}
+		// reactions don't get an ID string
+		return "", nil
+	}
+
 	// Delete message
 	if msg.Event == config.EventMsgDelete {
 		if msg.ID == "" {

bridge/discord/handlers.go

@@ -8,6 +8,34 @@ import (
 	"github.com/matterbridge-org/matterbridge/bridge/config"
 )
 
+func (b *Bdiscord) messageReaction(s *discordgo.Session, m *discordgo.MessageReactionAdd) { //nolint:unparam
+	b.Log.Debugf("Got a Discord Reaction:i %#v", m)
+	b.Log.Debugf("emoji = %#v", m.Emoji)
+
+	if m.GuildID != b.guildID {
+		b.Log.Debugf("Ignoring messageDelete because it originates from a different guild")
+		return
+	}
+
+	var reaction string
+	if m.Emoji.ID != "" {
+		// Discord has server-private emojis named with an ID
+		// Bridged these with a generic, neutral emoji.
+		// XXX chosing the neutralest of emojis might be .. hard.
+		reaction = "⬛"
+	} else {
+		reaction = m.Emoji.Name
+	}
+
+	// TODO: we need to bridge m.Emoji.User.Username or m.UserID
+	rmsg := config.Message{Account: b.Account, Event: config.EventReaction, ParentID: m.MessageID, Reactions: []string{reaction}}
+	rmsg.Channel = b.getChannelName(m.ChannelID)
+
+	b.Log.Debugf("<= Sending reaction from %s to gateway", b.Account)
+	b.Log.Debugf("<= Message is %#v", rmsg)
+	b.Remote <- rmsg
+}
+
 func (b *Bdiscord) messageDelete(s *discordgo.Session, m *discordgo.MessageDelete) { //nolint:unparam
 	if m.GuildID != b.guildID {
 		b.Log.Debugf("Ignoring messageDelete because it originates from a different guild")

bridge/xmpp/xmpp.go

@@ -34,8 +34,8 @@ type Bxmpp struct {
 	xc           *xmpp.Client
 	xmppMap      map[string]string
 	connected    bool
-	stanzaIDs    *lru.Cache[string, string]
-	replyHeaders *lru.Cache[string, xmpp.Reply]
+	stanzaIDs    *lru.Cache[string, string]     // stanzaID -> ID
+	replyHeaders *lru.Cache[string, xmpp.Reply] // ID -> Reply{stanzaID, to}
 	sync.RWMutex
 
 	avatarAvailability map[string]bool
@@ -158,9 +158,27 @@ func (b *Bxmpp) Send(msg config.Message) (string, error) {
 
 	// XEP-0461: populate reply fields if this message is a reply.
 	var reply *xmpp.Reply
+	var reactions *xmpp.Reactions
 	if msg.ParentValid() {
-		if _reply, ok := b.replyHeaders.Get(msg.ParentID); ok {
-			reply = &_reply
+		// either a Reaction or a Reply
+		//
+		if msg.Event == config.EventReaction {
+			b.Log.Debugf("relaying a Reaction; the reactions are %#v", msg.Reactions)
+			if _reply, ok := b.replyHeaders.Get(msg.ParentID); ok {
+				reactions = &xmpp.Reactions{
+					ID:        _reply.ID,
+					Reactions: msg.Reactions,
+				}
+			}
+
+			// XXX TODO: XEP-0444 says an update requires a *full* update for all reactions from a given user.
+			// since the bridge is the source of ALL reactions for all users on the other side,
+			// it needs to track what has been sent and *resend all of them*
+			// also it's going to lose past reactions messages...
+		} else {
+			if _reply, ok := b.replyHeaders.Get(msg.ParentID); ok {
+				reply = &_reply
+			}
 		}
 	}
 
@@ -169,11 +187,12 @@ func (b *Bxmpp) Send(msg config.Message) (string, error) {
 	// Generate a dummy ID because to avoid collision with other internal messages
 	msgID := xid.New().String()
 	if _, err := b.xc.Send(xmpp.Chat{
-		Type:     "groupchat",
-		Remote:   msg.Channel + "@" + b.GetString("Muc"),
-		Text:     msg.Username + msg.Text,
-		OriginID: msgID,
-		Reply:    reply,
+		Type:      "groupchat",
+		Remote:    msg.Channel + "@" + b.GetString("Muc"),
+		Text:      msg.Username + msg.Text,
+		OriginID:  msgID,
+		Reply:     reply,
+		Reactions: reactions,
 	}); err != nil {
 		return "", err
 	}
@@ -362,6 +381,17 @@ func (b *Bxmpp) handleXMPP() error {
 					parentText = v.Reply.Quote
 				}
 
+				// If there was a <reactions> // ....
+				var reactions []string
+				if v.Reactions != nil {
+					if _parentID, ok := b.stanzaIDs.Get(v.Reactions.ID); ok {
+						parentID = _parentID
+						b.Log.Debugf("Got reactions: %#v", v.Reactions)
+						reactions = append(reactions, v.Reactions.Reactions...) // XXX is the append() necessary?
+						event = config.EventReaction
+					}
+				}
+
 				rmsg := config.Message{
 					Username:   b.parseNick(v.Remote),
 					Text:       v.Text,
@@ -373,6 +403,7 @@ func (b *Bxmpp) handleXMPP() error {
 					Event:      event,
 					ParentID:   parentID,
 					ParentText: parentText,
+					Reactions:  reactions,
 				}
 
 				// Check if we have an action event.
@@ -499,7 +530,7 @@ func (b *Bxmpp) skipMessage(message xmpp.Chat) bool {
 	}
 
 	// skip empty messages
-	if message.Text == "" {
+	if message.Text == "" && message.Reactions == nil {
 		return true
 	}
 

gateway/gateway.go

@@ -291,6 +291,9 @@ func (gw *Gateway) ignoreTextEmpty(msg *config.Message) bool {
 	if msg.Text != "" {
 		return false
 	}
+	if msg.Event == config.EventReaction {
+		return false
+	}
 	if msg.Event == config.EventUserTyping {
 		return false
 	}

go.mod

@@ -159,4 +159,4 @@ require (
 
 go 1.25.0
 
-replace github.com/xmppo/go-xmpp => github.com/sh4sh/go-xmpp v0.0.0-20260306054259-9e62a00d8f50
+replace github.com/xmppo/go-xmpp => github.com/sh4sh/go-xmpp v0.0.0-20260308194659-485ad27aa55a

go.sum

@@ -313,8 +313,8 @@ github.com/saintfish/chardet v0.0.0-20230101081208-5e3ef4b5456d/go.mod h1:uugorj
 github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
 github.com/sergi/go-diff v1.3.1 h1:xkr+Oxo4BOQKmkn/B9eMK0g5Kg/983T9DqqPHwYqD+8=
 github.com/sergi/go-diff v1.3.1/go.mod h1:aMJSSKb2lpPvRNec0+w3fl7LP9IOFzdc9Pa4NFbPK1I=
-github.com/sh4sh/go-xmpp v0.0.0-20260306054259-9e62a00d8f50 h1:rhsp1fFzf4hnYUY4E83bpzDprbGyg7oXU0CHj5rwWAk=
-github.com/sh4sh/go-xmpp v0.0.0-20260306054259-9e62a00d8f50/go.mod h1:U1T7Fv9GY+8pJpOwEpNII37JLngt31TiRHzHV3m66tc=
+github.com/sh4sh/go-xmpp v0.0.0-20260308194659-485ad27aa55a h1:/Id+09ZFYZGdBqpVqMUTrRznLUpD66dOunIWeRiqMTQ=
+github.com/sh4sh/go-xmpp v0.0.0-20260308194659-485ad27aa55a/go.mod h1:U1T7Fv9GY+8pJpOwEpNII37JLngt31TiRHzHV3m66tc=
 github.com/shazow/rateio v0.0.0-20200113175441-4461efc8bdc4 h1:zwQ1HBo5FYwn1ksMd19qBCKO8JAWE9wmHivEpkw/DvE=
 github.com/shazow/rateio v0.0.0-20200113175441-4461efc8bdc4/go.mod h1:vt2jWY/3Qw1bIzle5thrJWucsLuuX9iUNnp20CqCciI=
 github.com/shazow/ssh-chat v1.10.1 h1:ePS+ngEYqm+yUuXegDPutysqLV2WoI22XDOeRgI6CE0=