Use our read receipt to calculate whether rooms are unread.

src/Unread.js

@@ -0,0 +1,49 @@
+/*
+Copyright 2015 OpenMarket Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+var MatrixClientPeg = require('./MatrixClientPeg');
+
+module.exports = {
+    /**
+     * Returns true iff this event arriving in a room should affect the room's
+     * count of unread messages
+     */
+    eventTriggersUnreadCount: function(ev) {
+        if (ev.getType() == "m.room.member") {
+            return false;
+        } else if (ev.getType == 'm.room.message' && ev.getContent().msgtype == 'm.notify') {
+            return false;
+        }
+        return true;
+    },
+
+    doesRoomHaveUnreadMessages: function(room) {
+        var readUpToId = room.getEventReadUpTo(MatrixClientPeg.get().credentials.userId);
+        var unread = false;
+        for (var i = room.timeline.length - 1; i >= 0; --i) {
+            var ev = room.timeline[i];
+
+            if (ev.getId() == readUpToId) {
+                break;
+            }
+
+            if (this.eventTriggersUnreadCount(ev)) {
+                unread = true;
+            }
+        }
+        return unread;
+    }
+};