Add initial support for getting ChannelMember info of all bridges (#678)

* Add initial support for getting ChannelMember info of all bridges.

Adds an EventGetChannelMembers event, which gets send every x time to
all bridges. Bridges should respond on this event with a Message
containing ChannelMembers in the EventGetChannelMembers key in the
Extra field.

handleEventGetChannelMembers will handle this Message and sets the
contained ChannelMembers to the Bridge struct.

* Add ChannelMembers support to the slack bridge

3 files changed, 106 insertions, 0 deletions

diff --git a/bridge/slack/handlers.go b/bridge/slack/handlers.go
index f46eb595..5e601eaa 100644
--- a/bridge/slack/handlers.go
+++ b/bridge/slack/handlers.go
@@ -309,6 +309,58 @@ func (b *Bslack) handleDownloadFile(rmsg *config.Message, file *slack.File, retr
 	return nil
 }
 
+// handleGetChannelMembers handles messages containing the GetChannelMembers event
+// Sends a message to the router containing *config.ChannelMembers
+func (b *Bslack) handleGetChannelMembers(rmsg *config.Message) bool {
+	if rmsg.Event != config.EventGetChannelMembers {
+		return false
+	}
+
+	cMembers := config.ChannelMembers{}
+
+	b.channelMembersMutex.RLock()
+
+	for channelID, members := range b.channelMembers {
+		for _, member := range members {
+			channelName := ""
+			userName := ""
+			userNick := ""
+			user := b.getUser(member)
+			if user != nil {
+				userName = user.Name
+				userNick = user.Profile.DisplayName
+			}
+			channel, _ := b.getChannelByID(channelID)
+			if channel != nil {
+				channelName = channel.Name
+			}
+			cMember := config.ChannelMember{
+				Username:    userName,
+				Nick:        userNick,
+				UserID:      member,
+				ChannelID:   channelID,
+				ChannelName: channelName,
+			}
+			cMembers = append(cMembers, cMember)
+		}
+	}
+
+	b.channelMembersMutex.RUnlock()
+
+	extra := make(map[string][]interface{})
+	extra[config.EventGetChannelMembers] = append(extra[config.EventGetChannelMembers], cMembers)
+	msg := config.Message{
+		Extra:   extra,
+		Event:   config.EventGetChannelMembers,
+		Account: b.Account,
+	}
+
+	b.Log.Debugf("sending msg to remote %#v", msg)
+	b.Remote <- msg
+
+	return true
+}
+
 // fileCached implements Matterbridge's caching logic for files
 // shared via Slack.
 //
diff --git a/bridge/slack/helpers.go b/bridge/slack/helpers.go
index 4e6e5652..d84353f0 100644
--- a/bridge/slack/helpers.go
+++ b/bridge/slack/helpers.go
@@ -93,7 +93,9 @@ func (b *Bslack) populateUsers(wait bool) {
 		return
 	}
 	for b.refreshInProgress {
+		b.refreshMutex.Unlock()
 		time.Sleep(time.Second)
+		b.refreshMutex.Lock()
 	}
 	b.refreshInProgress = true
 	b.refreshMutex.Unlock()
@@ -139,13 +141,16 @@ func (b *Bslack) populateChannels(wait bool) {
 		return
 	}
 	for b.refreshInProgress {
+		b.refreshMutex.Unlock()
 		time.Sleep(time.Second)
+		b.refreshMutex.Lock()
 	}
 	b.refreshInProgress = true
 	b.refreshMutex.Unlock()
 
 	newChannelsByID := map[string]*slack.Channel{}
 	newChannelsByName := map[string]*slack.Channel{}
+	newChannelMembers := make(map[string][]string)
 
 	// We only retrieve public and private channels, not IMs
 	// and MPIMs as those do not have a channel name.
@@ -166,7 +171,18 @@ func (b *Bslack) populateChannels(wait bool) {
 		for i := range channels {
 			newChannelsByID[channels[i].ID] = &channels[i]
 			newChannelsByName[channels[i].Name] = &channels[i]
+			// also find all the members in every channel
+			members, err := b.getUsersInConversation(channels[i].ID)
+			if err != nil {
+				if err = b.handleRateLimit(err); err != nil {
+					b.Log.Errorf("Could not retrieve channel members: %#v", err)
+					return
+				}
+				continue
+			}
+			newChannelMembers[channels[i].ID] = members
 		}
+
 		if nextCursor == "" {
 			break
 		}
@@ -178,6 +194,10 @@ func (b *Bslack) populateChannels(wait bool) {
 	b.channelsByID = newChannelsByID
 	b.channelsByName = newChannelsByName
 
+	b.channelMembersMutex.Lock()
+	defer b.channelMembersMutex.Unlock()
+	b.channelMembers = newChannelMembers
+
 	b.refreshMutex.Lock()
 	defer b.refreshMutex.Unlock()
 	b.earliestChannelRefresh = time.Now().Add(minimumRefreshInterval)
@@ -367,3 +387,29 @@ func (b *Bslack) handleRateLimit(err error) error {
 	time.Sleep(rateLimit.RetryAfter)
 	return nil
 }
+
+// getUsersInConversation returns an array of userIDs that are members of channelID
+func (b *Bslack) getUsersInConversation(channelID string) ([]string, error) {
+	channelMembers := []string{}
+	for {
+		queryParams := &slack.GetUsersInConversationParameters{
+			ChannelID: channelID,
+		}
+
+		members, nextCursor, err := b.sc.GetUsersInConversation(queryParams)
+		if err != nil {
+			if err = b.handleRateLimit(err); err != nil {
+				return channelMembers, fmt.Errorf("Could not retrieve users in channels: %#v", err)
+			}
+			continue
+		}
+
+		channelMembers = append(channelMembers, members...)
+
+		if nextCursor == "" {
+			break
+		}
+		queryParams.Cursor = nextCursor
+	}
+	return channelMembers, nil
+}
diff --git a/bridge/slack/slack.go b/bridge/slack/slack.go
index b9430278..001b1268 100644
--- a/bridge/slack/slack.go
+++ b/bridge/slack/slack.go
@@ -37,6 +37,9 @@ type Bslack struct {
 	channelsByName map[string]*slack.Channel
 	channelsMutex  sync.RWMutex
 
+	channelMembers      map[string][]string
+	channelMembersMutex sync.RWMutex
+
 	refreshInProgress      bool
 	earliestChannelRefresh time.Time
 	earliestUserRefresh    time.Time
@@ -267,6 +270,11 @@ func (b *Bslack) sendWebhook(msg config.Message) error {
 }
 
 func (b *Bslack) sendRTM(msg config.Message) (string, error) {
+	// Handle channelmember messages.
+	if handled := b.handleGetChannelMembers(&msg); handled {
+		return "", nil
+	}
+
 	channelInfo, err := b.getChannel(msg.Channel)
 	if err != nil {
 		return "", fmt.Errorf("could not send message: %v", err)