make presence work when peeking. fixes https://github.com/vector-im/vector-web/issues/780

lib/sync.js

@@ -225,6 +225,25 @@ SyncApi.prototype.peek = function(roomId) {
             response.messages.chunk, client.getEventMapper()
         );
 
+        // XXX: copypasted from /sync until we kill off this
+        // minging v1 API stuff)
+        // handle presence events (User objects)
+        if (response.presence && utils.isArray(response.presence)) {
+            response.presence.map(client.getEventMapper()).forEach(
+            function(presenceEvent) {
+                var user = client.store.getUser(presenceEvent.getContent().user_id);
+                if (user) {
+                    user.setPresenceEvent(presenceEvent);
+                }
+                else {
+                    user = createNewUser(client, presenceEvent.getContent().user_id);
+                    user.setPresenceEvent(presenceEvent);
+                    client.store.storeUser(user);
+                }
+                client.emit("event", presenceEvent);
+            });
+        }
+
         // set the pagination token before adding the events in case people
         // fire off pagination requests in response to the Room.timeline
         // events.
@@ -279,6 +298,31 @@ SyncApi.prototype._peekPoll = function(roomId, token) {
         timeout: 30 * 1000,
         from: token
     }, undefined, 50 * 1000).done(function(res) {
+
+        // We have a problem that we get presence both from /events and /sync
+        // however, /sync only returns presence for users in rooms
+        // you're actually joined to.
+        // in order to be sure to get presence for all of the users in the
+        // peeked room, we handle presence explicitly here. This may result
+        // in duplicate presence events firing for some users, which is a
+        // performance drain, but such is life.
+        // XXX: copypasted from /sync until we can kill this minging v1 stuff.
+
+        res.chunk.filter(function(e) {
+            return e.type === "m.presence";
+        }).map(self.client.getEventMapper()).map(function(presenceEvent) {
+            var user = self.client.store.getUser(presenceEvent.getContent().user_id);
+            if (user) {
+                user.setPresenceEvent(presenceEvent);
+            }
+            else {
+                user = createNewUser(self.client, presenceEvent.getContent().user_id);
+                user.setPresenceEvent(presenceEvent);
+                self.client.store.storeUser(user);
+            }
+            self.client.emit("event", presenceEvent);
+        });
+
         // strip out events which aren't for the given room_id (e.g presence)
         var events = res.chunk.filter(function(e) {
             return e.room_id === roomId;