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

gateway/handlers.go

@@ -30,6 +30,23 @@ func (r *Router) handleEventFailure(msg *config.Message) {
 	}
 }
 
+// handleEventGetChannelMembers handles channel members
+func (r *Router) handleEventGetChannelMembers(msg *config.Message) {
+	if msg.Event != config.EventGetChannelMembers {
+		return
+	}
+	for _, gw := range r.Gateways {
+		for _, br := range gw.Bridges {
+			if msg.Account == br.Account {
+				cMembers := msg.Extra[config.EventGetChannelMembers][0].(config.ChannelMembers)
+				flog.Debugf("Syncing channelmembers from %s", msg.Account)
+				br.SetChannelMembers(&cMembers)
+				return
+			}
+		}
+	}
+}
+
 // handleEventRejoinChannels handles rejoining of channels.
 func (r *Router) handleEventRejoinChannels(msg *config.Message) {
 	if msg.Event != config.EventRejoinChannels {

gateway/router.go

@@ -2,6 +2,7 @@ package gateway
 
 import (
 	"fmt"
+	"sync"
 	"time"
 
 	"github.com/42wim/matterbridge/bridge"
@@ -16,6 +17,7 @@ type Router struct {
 	Gateways         map[string]*Gateway
 	Message          chan config.Message
 	MattermostPlugin chan config.Message
+	sync.RWMutex
 }
 
 func NewRouter(cfg config.Config, bridgeMap map[string]bridge.Factory) (*Router, error) {
@@ -81,6 +83,7 @@ func (r *Router) Start() error {
 		}
 	}
 	go r.handleReceive()
+	go r.updateChannelMembers()
 	return nil
 }
 
@@ -108,6 +111,7 @@ func (r *Router) getBridge(account string) *bridge.Bridge {
 func (r *Router) handleReceive() {
 	for msg := range r.Message {
 		msg := msg // scopelint
+		r.handleEventGetChannelMembers(&msg)
 		r.handleEventFailure(&msg)
 		r.handleEventRejoinChannels(&msg)
 		for _, gw := range r.Gateways {
@@ -129,3 +133,21 @@ func (r *Router) handleReceive() {
 		}
 	}
 }
+
+// updateChannelMembers sends every minute an GetChannelMembers event to all bridges.
+func (r *Router) updateChannelMembers() {
+	// TODO sleep a minute because slack can take a while
+	// fix this by having actually connectionDone events send to the router
+	time.Sleep(time.Minute)
+	for {
+		for _, gw := range r.Gateways {
+			for _, br := range gw.Bridges {
+				flog.Debugf("sending %s to %s", config.EventGetChannelMembers, br.Account)
+				if _, err := br.Send(config.Message{Event: config.EventGetChannelMembers}); err != nil {
+					flog.Errorf("updateChannelMembers: %s", err)
+				}
+			}
+		}
+		time.Sleep(time.Minute)
+	}
+}