Debounce updates to notifications and other events

Wait for one second of silence before displaying new notifications,
updating the unread count and conversation list previews.

Fixes #470

js/conversation_controller.js

@@ -13,9 +13,12 @@
     var inboxCollection = new (Backbone.Collection.extend({
         initialize: function() {
             this.on('change:timestamp change:name change:number', this.sort);
-            this.on('add remove change:unreadCount', this.updateUnreadCount);
 
             this.listenTo(conversations, 'add change:active_at', this.addActive);
+
+            this.on('add remove change:unreadCount',
+                _.debounce(this.updateUnreadCount.bind(this), 1000)
+            );
         },
         comparator: function(m1, m2) {
             var timestamp1 = m1.get('timestamp');
@@ -48,7 +51,7 @@
                 this.remove(model);
             }
         },
-        updateUnreadCount: function(model, count) {
+        updateUnreadCount: function() {
             var newUnreadCount = _.reduce(
                 this.map(function(m) { return m.get('unreadCount'); }),
                 function(item, memo) {

js/notifications.js

@@ -14,7 +14,7 @@
 
     Whisper.Notifications = new (Backbone.Collection.extend({
         initialize: function() {
-            this.on('add', this.onAdd);
+            this.on('add', _.debounce(this.update.bind(this), 1000));
             this.on('remove', this.onRemove);
         },
         onclick: function() {
@@ -30,6 +30,10 @@
             this.clear();
         },
         update: function() {
+            extension.notification.clear();
+            if (this.length === 0) {
+                return;
+            }
             var setting = storage.get('notification-setting') || 'message';
             if (setting === SETTINGS.OFF) {
                 return;
@@ -116,10 +120,6 @@
             var setting = this.getSetting();
             return (setting === SETTINGS.MESSAGE || setting === SETTINGS.NAME);
         },
-        onAdd: function() {
-            extension.notification.clear();
-            this.update();
-        },
         onRemove: function() {
             if (this.length === 0) {
                 extension.notification.clear();

js/views/conversation_list_item_view.js

@@ -16,7 +16,8 @@
             'click': 'select'
         },
         initialize: function() {
-            this.listenTo(this.model, 'change', this.render); // auto update
+            // auto update
+            this.listenTo(this.model, 'change', _.debounce(this.render.bind(this), 1000));
             this.listenTo(this.model, 'destroy', this.remove); // auto update
             this.listenTo(this.model, 'opened', this.markSelected); // auto update
             extension.windows.onClosed(this.stopListening.bind(this));