Add support for deleting messages across bridges.

Currently fully support mattermost,slack and discord.
Message deleted on the bridge or received from other bridges will be
deleted.

Partially support for Gitter.
Gitter bridge will delete messages received from other bridges.
But if you delete a message on gitter, this deletion will not be sent to
other bridges (this is a gitter API limitation, it doesn't propogate edits
or deletes via the API)

bridge/api/api.go

@@ -69,6 +69,10 @@ func (b *Api) JoinChannel(channel config.ChannelInfo) error {
 func (b *Api) Send(msg config.Message) (string, error) {
 	b.Lock()
 	defer b.Unlock()
+	// ignore delete messages
+	if msg.Event == config.EVENT_MSG_DELETE {
+		return "", nil
+	}
 	b.Messages.Enqueue(&msg)
 	return "", nil
 }

bridge/config/config.go

@@ -14,6 +14,7 @@ const (
 	EVENT_FAILURE         = "failure"
 	EVENT_REJOIN_CHANNELS = "rejoin_channels"
 	EVENT_USER_ACTION     = "user_action"
+	EVENT_MSG_DELETE      = "msg_delete"
 )
 
 type Message struct {

bridge/discord/discord.go

@@ -66,6 +66,7 @@ func (b *bdiscord) Connect() error {
 	b.c.AddHandler(b.messageCreate)
 	b.c.AddHandler(b.memberUpdate)
 	b.c.AddHandler(b.messageUpdate)
+	b.c.AddHandler(b.messageDelete)
 	err = b.c.Open()
 	if err != nil {
 		flog.Debugf("%#v", err)
@@ -129,6 +130,13 @@ func (b *bdiscord) Send(msg config.Message) (string, error) {
 
 	if wID == "" {
 		flog.Debugf("Broadcasting using token (API)")
+		if msg.Event == config.EVENT_MSG_DELETE {
+			if msg.ID == "" {
+				return "", nil
+			}
+			err := b.c.ChannelMessageDelete(channelID, msg.ID)
+			return "", err
+		}
 		if msg.ID != "" {
 			_, err := b.c.ChannelMessageEdit(channelID, msg.ID, msg.Username+msg.Text)
 			return msg.ID, err
@@ -152,6 +160,17 @@ func (b *bdiscord) Send(msg config.Message) (string, error) {
 	return "", err
 }
 
+func (b *bdiscord) messageDelete(s *discordgo.Session, m *discordgo.MessageDelete) {
+	rmsg := config.Message{Account: b.Account, ID: m.ID, Event: config.EVENT_MSG_DELETE, Text: config.EVENT_MSG_DELETE}
+	rmsg.Channel = b.getChannelName(m.ChannelID)
+	if b.UseChannelID {
+		rmsg.Channel = "ID:" + m.ChannelID
+	}
+	flog.Debugf("Sending message from %s to gateway", b.Account)
+	flog.Debugf("Message is %#v", rmsg)
+	b.Remote <- rmsg
+}
+
 func (b *bdiscord) messageUpdate(s *discordgo.Session, m *discordgo.MessageUpdate) {
 	if b.Config.EditDisable {
 		return
@@ -223,6 +242,7 @@ func (b *bdiscord) messageCreate(s *discordgo.Session, m *discordgo.MessageCreat
 
 	rmsg.Text = text
 	flog.Debugf("Sending message from %s on %s to gateway", m.Author.Username, b.Account)
+	flog.Debugf("Message is %#v", rmsg)
 	b.Remote <- rmsg
 }
 

bridge/gitter/gitter.go

@@ -106,6 +106,17 @@ func (b *Bgitter) Send(msg config.Message) (string, error) {
 		flog.Errorf("Could not find roomID for %v", msg.Channel)
 		return "", nil
 	}
+	if msg.Event == config.EVENT_MSG_DELETE {
+		if msg.ID == "" {
+			return "", nil
+		}
+		// gitter has no delete message api
+		_, err := b.c.UpdateMessage(roomID, msg.ID, "")
+		if err != nil {
+			return "", err
+		}
+		return "", nil
+	}
 	if msg.ID != "" {
 		flog.Debugf("updating message with id %s", msg.ID)
 		_, err := b.c.UpdateMessage(roomID, msg.ID, msg.Username+msg.Text)

bridge/irc/irc.go

@@ -129,6 +129,10 @@ func (b *Birc) JoinChannel(channel config.ChannelInfo) error {
 }
 
 func (b *Birc) Send(msg config.Message) (string, error) {
+	// ignore delete messages
+	if msg.Event == config.EVENT_MSG_DELETE {
+		return "", nil
+	}
 	flog.Debugf("Receiving %#v", msg)
 	if strings.HasPrefix(msg.Text, "!") {
 		b.Command(&msg)

bridge/matrix/matrix.go

@@ -76,6 +76,10 @@ func (b *Bmatrix) JoinChannel(channel config.ChannelInfo) error {
 
 func (b *Bmatrix) Send(msg config.Message) (string, error) {
 	flog.Debugf("Receiving %#v", msg)
+	// ignore delete messages
+	if msg.Event == config.EVENT_MSG_DELETE {
+		return "", nil
+	}
 	channel := b.getRoomID(msg.Channel)
 	flog.Debugf("Sending to channel %s", channel)
 	if msg.Event == config.EVENT_USER_ACTION {

bridge/mattermost/mattermost.go

@@ -25,6 +25,7 @@ type MMMessage struct {
 	Username string
 	UserID   string
 	ID       string
+	Event    string
 }
 
 type Bmattermost struct {
@@ -168,6 +169,12 @@ func (b *Bmattermost) Send(msg config.Message) (string, error) {
 		}
 		return "", nil
 	}
+	if msg.Event == config.EVENT_MSG_DELETE {
+		if msg.ID == "" {
+			return "", nil
+		}
+		return msg.ID, b.mc.DeleteMessage(msg.ID)
+	}
 	if msg.ID != "" {
 		return b.mc.EditMessage(msg.ID, message)
 	}
@@ -188,7 +195,7 @@ func (b *Bmattermost) handleMatter() {
 		go b.handleMatterClient(mchan)
 	}
 	for message := range mchan {
-		rmsg := config.Message{Username: message.Username, Channel: message.Channel, Account: b.Account, UserID: message.UserID, ID: message.ID}
+		rmsg := config.Message{Username: message.Username, Channel: message.Channel, Account: b.Account, UserID: message.UserID, ID: message.ID, Event: message.Event}
 		text, ok := b.replaceAction(message.Text)
 		if ok {
 			rmsg.Event = config.EVENT_USER_ACTION
@@ -215,7 +222,7 @@ func (b *Bmattermost) handleMatterClient(mchan chan *MMMessage) {
 		}
 		// do not post our own messages back to irc
 		// only listen to message from our team
-		if (message.Raw.Event == "posted" || message.Raw.Event == "post_edited") &&
+		if (message.Raw.Event == "posted" || message.Raw.Event == "post_edited" || message.Raw.Event == "post_deleted") &&
 			b.mc.User.Username != message.Username && message.Raw.Data["team_id"].(string) == b.TeamId {
 			// if the message has reactions don't repost it (for now, until we can correlate reaction with message)
 			if message.Post.HasReactions {
@@ -231,6 +238,9 @@ func (b *Bmattermost) handleMatterClient(mchan chan *MMMessage) {
 			if message.Raw.Event == "post_edited" && !b.Config.EditDisable {
 				m.Text = message.Text + b.Config.EditSuffix
 			}
+			if message.Raw.Event == "post_deleted" {
+				m.Event = config.EVENT_MSG_DELETE
+			}
 			if len(message.Post.FileIds) > 0 {
 				for _, link := range b.mc.GetFileLinks(message.Post.FileIds) {
 					m.Text = m.Text + "\n" + link

bridge/rocketchat/rocketchat.go

@@ -58,6 +58,10 @@ func (b *Brocketchat) JoinChannel(channel config.ChannelInfo) error {
 }
 
 func (b *Brocketchat) Send(msg config.Message) (string, error) {
+	// ignore delete messages
+	if msg.Event == config.EVENT_MSG_DELETE {
+		return "", nil
+	}
 	flog.Debugf("Receiving %#v", msg)
 	matterMessage := matterhook.OMessage{IconURL: b.Config.IconURL}
 	matterMessage.Channel = msg.Channel

bridge/slack/slack.go

@@ -166,6 +166,16 @@ func (b *Bslack) Send(msg config.Message) (string, error) {
 	// replace mentions
 	np.LinkNames = 1
 
+	if msg.Event == config.EVENT_MSG_DELETE {
+		// some protocols echo deletes, but with empty ID
+		if msg.ID == "" {
+			return "", nil
+		}
+		// we get a "slack <ID>", split it
+		ts := strings.Fields(msg.ID)
+		b.sc.DeleteMessage(schannel.ID, ts[1])
+		return "", nil
+	}
 	// if we have no ID it means we're creating a new message, not updating an existing one
 	if msg.ID != "" {
 		ts := strings.Fields(msg.ID)
@@ -231,7 +241,7 @@ func (b *Bslack) handleSlack() {
 		if b.Config.WebhookURL == "" && b.Config.WebhookBindAddress == "" && message.Username == b.si.User.Name {
 			continue
 		}
-		if message.Text == "" || message.Username == "" {
+		if (message.Text == "" || message.Username == "") && message.Raw.SubType != "message_deleted" {
 			continue
 		}
 		text := message.Text
@@ -250,6 +260,12 @@ func (b *Bslack) handleSlack() {
 		if message.Raw.SubMessage != nil {
 			msg.ID = "slack " + message.Raw.SubMessage.Timestamp
 		}
+		if message.Raw.SubType == "message_deleted" {
+			msg.Text = config.EVENT_MSG_DELETE
+			msg.Event = config.EVENT_MSG_DELETE
+			msg.ID = "slack " + message.Raw.DeletedTimestamp
+		}
+		flog.Debugf("Message is %#v", msg)
 		b.Remote <- msg
 	}
 }
@@ -276,7 +292,7 @@ func (b *Bslack) handleSlackClient(mchan chan *MMMessage) {
 				continue
 			}
 			m := &MMMessage{}
-			if ev.BotID == "" {
+			if ev.BotID == "" && ev.SubType != "message_deleted" {
 				user, err := b.rtm.GetUserInfo(ev.User)
 				if err != nil {
 					continue

bridge/steam/steam.go

@@ -70,6 +70,10 @@ func (b *Bsteam) JoinChannel(channel config.ChannelInfo) error {
 }
 
 func (b *Bsteam) Send(msg config.Message) (string, error) {
+	// ignore delete messages
+	if msg.Event == config.EVENT_MSG_DELETE {
+		return "", nil
+	}
 	id, err := steamid.NewId(msg.Channel)
 	if err != nil {
 		return "", err

bridge/xmpp/xmpp.go

@@ -80,6 +80,10 @@ func (b *Bxmpp) JoinChannel(channel config.ChannelInfo) error {
 }
 
 func (b *Bxmpp) Send(msg config.Message) (string, error) {
+	// ignore delete messages
+	if msg.Event == config.EVENT_MSG_DELETE {
+		return "", nil
+	}
 	flog.Debugf("Receiving %#v", msg)
 	b.xc.Send(xmpp.Chat{Type: "groupchat", Remote: msg.Channel + "@" + b.Config.Muc, Text: msg.Username + msg.Text})
 	return "", nil

changelog.md

@@ -1,6 +1,9 @@
 # v1.1.2
+## New features
 * general: also build darwin binaries
 * mattermost: add support for mattermost 4.2.x
+
+## Bugfix 
 * mattermost: Send images when text is empty regression. (mattermost). Closes #254
 * slack: also send the first messsage after connect. #252
 

matterclient/matterclient.go

@@ -299,7 +299,7 @@ func (m *MMClient) WsReceiver() {
 
 func (m *MMClient) parseMessage(rmsg *Message) {
 	switch rmsg.Raw.Event {
-	case model.WEBSOCKET_EVENT_POSTED, model.WEBSOCKET_EVENT_POST_EDITED:
+	case model.WEBSOCKET_EVENT_POSTED, model.WEBSOCKET_EVENT_POST_EDITED, model.WEBSOCKET_EVENT_POST_DELETED:
 		m.parseActionPost(rmsg)
 		/*
 			case model.ACTION_USER_REMOVED:
@@ -476,6 +476,14 @@ func (m *MMClient) EditMessage(postId string, text string) (string, error) {
 	return res.Id, nil
 }
 
+func (m *MMClient) DeleteMessage(postId string) error {
+	_, resp := m.Client.DeletePost(postId)
+	if resp.Error != nil {
+		return resp.Error
+	}
+	return nil
+}
+
 func (m *MMClient) JoinChannel(channelId string) error {
 	m.RLock()
 	defer m.RUnlock()