Refactor delivery receipt tracking

Move code for matching receipts to messages (and vice versa) to its own
file.

// FREEBIE

background.html

@@ -394,6 +394,7 @@
   <script type='text/javascript' src='js/libtextsecure.js'></script>
 
   <script type='text/javascript' src='js/notifications.js'></script>
+  <script type='text/javascript' src='js/delivery_receipts.js'></script>
   <script type='text/javascript' src='js/libphonenumber-util.js'></script>
   <script type='text/javascript' src='js/models/messages.js'></script>
   <script type='text/javascript' src='js/models/conversations.js'></script>

js/background.js

@@ -278,43 +278,14 @@
     function onDeliveryReceipt(ev) {
         var pushMessage = ev.proto;
         var timestamp = pushMessage.timestamp.toNumber();
-        var messages  = new Whisper.MessageCollection();
-        var groups    = new Whisper.ConversationCollection();
         console.log(
             'delivery receipt from',
             pushMessage.source + '.' + pushMessage.sourceDevice,
             timestamp
         );
 
-        groups.fetchGroups(pushMessage.source).then(function() {
-            messages.fetchSentAt(timestamp).then(function() {
-                var ids = groups.pluck('id');
-                ids.push(pushMessage.source);
-                var message = messages.find(function(message) {
-                    return (!message.isIncoming() &&
-                            _.contains(ids, message.get('conversationId')));
-                });
-                if (message) {
-                    var deliveries = message.get('delivered') || 0;
-                    message.save({delivered: deliveries + 1}).then(function() {
-                        // notify frontend listeners
-                        var conversation = ConversationController.get(
-                            message.get('conversationId')
-                        );
-                        if (conversation) {
-                            conversation.trigger('newmessage', message);
-                        }
-                    });
-                    // TODO: consider keeping a list of numbers we've
-                    // successfully delivered to?
-                    return;
-                }
-                // if we get here, we didn't find a matching message.
-                // keep the receipt in memory in case it shows up later
-                // as a sync message.
-                receipts.add({ timestamp: timestamp, source: pushMessage.source });
-                return;
-            });
+        Whisper.DeliveryReceipts.add({
+            timestamp: timestamp, source: pushMessage.source
         });
     }
 })();

js/delivery_receipts.js

@@ -0,0 +1,58 @@
+/*
+ * vim: ts=4:sw=4:expandtab
+ */
+;(function() {
+    'use strict';
+    window.Whisper = window.Whisper || {};
+    Whisper.DeliveryReceipts = new (Backbone.Collection.extend({
+        initialize: function() {
+            this.on('add', this.onReceipt);
+        },
+        forMessage: function(conversation, message) {
+            var recipients;
+            if (conversation.isPrivate()) {
+                recipients = [ conversation.id ];
+            } else {
+                recipients = conversation.get('members') || [];
+            }
+            var receipts = this.filter(function(receipt) {
+                return (receipt.get('timestamp') === message.get('sent_at')) &&
+                    (recipients.indexOf(receipt.get('source')) > -1);
+            });
+            this.remove(receipts);
+            return receipts;
+        },
+        onReceipt: function(receipt) {
+            var messages  = new Whisper.MessageCollection();
+            var groups    = new Whisper.ConversationCollection();
+            Promise.all([
+                groups.fetchGroups(receipt.get('source')),
+                messages.fetchSentAt(receipt.get('timestamp'))
+            ]).then(function() {
+                var ids = groups.pluck('id');
+                ids.push(receipt.get('source'));
+                var message = messages.find(function(message) {
+                    return (!message.isIncoming() &&
+                            _.contains(ids, message.get('conversationId')));
+                });
+                if (message) {
+                    this.remove(receipt);
+                    var deliveries = message.get('delivered') || 0;
+                    message.save({
+                        delivered: deliveries + 1
+                    }).then(function() {
+                        // notify frontend listeners
+                        var conversation = ConversationController.get(
+                            message.get('conversationId')
+                        );
+                        if (conversation) {
+                            conversation.trigger('newmessage', message);
+                        }
+                    });
+                    // TODO: consider keeping a list of numbers we've
+                    // successfully delivered to?
+                }
+            }.bind(this));
+        }
+    }))();
+})();

js/models/conversations.js

@@ -509,12 +509,14 @@
     },
 
     fetchGroups: function(number) {
-        return this.fetch({
-            index: {
-                name: 'group',
-                only: number
-            }
-        });
+        return new Promise(function(resolve) {
+            this.fetch({
+                index: {
+                    name: 'group',
+                    only: number
+                }
+            }).always(resolve);
+        }.bind(this));
     },
 
     fetchActive: function() {

js/models/messages.js

@@ -317,18 +317,8 @@
                             }
                         }
                         if (type === 'outgoing') {
-                            // lazy hack - check for receipts that arrived early.
-                            var recipients;
-                            if (dataMessage.group && dataMessage.group.id) {  // group sync
-                                recipients = conversation.get('members') || [];
-                            } else {
-                                recipients = [ conversation.id ];
-                            }
-                            window.receipts.filter(function(receipt) {
-                                return (receipt.get('timestamp') === timestamp) &&
-                                    (recipients.indexOf(receipt.get('source')) > -1);
-                            }).forEach(function(receipt) {
-                                window.receipts.remove(receipt);
+                            var receipts = Whisper.DeliveryReceipts.forMessage(conversation, message);
+                            receipts.forEach(function(receipt) {
                                 message.set({
                                     delivered: (message.get('delivered') || 0) + 1
                                 });
@@ -402,13 +392,15 @@
         },
 
         fetchSentAt: function(timestamp) {
-            return this.fetch({
-                index: {
-                    // 'receipt' index on sent_at
-                    name: 'receipt',
-                    only: timestamp
-                }
-            });
+            return new Promise(function(resolve) {
+                return this.fetch({
+                    index: {
+                        // 'receipt' index on sent_at
+                        name: 'receipt',
+                        only: timestamp
+                    }
+                }).always(resolve);
+            }.bind(this));
         },
 
         fetchConversation: function(conversationId, limit) {