Implicit read receipts

* Inject implicit read receipts into the timeline
 * Twiddle local echo a bit to make the implicit receipts match the various different stages of local echo.

lib/client.js

@@ -946,6 +946,9 @@ function _sendEvent(client, room, event, callback) {
             // the fake event we made above. If we don't find it, we're still
             // waiting on the real event and so should assign the fake event
             // with the real event_id for matching later.
+
+            // FIXME: This manipulation of the room should probably be done
+            // inside the room class, not by the client.
             var matchingEvent = utils.findElement(room.timeline, function(ev) {
                 return ev.getId() === eventId;
             }, true);
@@ -958,13 +961,13 @@ function _sendEvent(client, room, event, callback) {
                     matchingEvent.event.content = event.event.content;
                     matchingEvent.event.type = event.event.type;
                 }
-                utils.removeElement(room.timeline, function(ev) {
-                    return ev.getId() === event.getId();
-                }, true);
+                room.removeEvents([event.getId()]);
             }
             else {
+                room.removeEvents([event.getId()]);
                 event.event.event_id = res.event_id;
                 event.status = null;
+                room.addEventsToTimeline([event]);
             }
         }
 

lib/models/room.js

@@ -194,7 +194,26 @@ Room.prototype.addEventsToTimeline = function(events, toStartOfTimeline) {
         else {
             this.timeline.push(events[i]);
         }
-        this.emit("Room.timeline", events[i], this, Boolean(toStartOfTimeline));
+
+        // synthesize and inject implicit read receipts
+        // Done after adding the event because otherwise the app would get a read receipt
+        // pointing to an event that wasn't yet in the timeline
+
+        // This is really ugly because JS has no way to express an object literal where the
+        // name of a key comes from an expression
+        if (events[i].sender) {
+            var fakeReceipt = {content: {}};
+            fakeReceipt.content[events[i].getId()] = {
+                'm.read': {
+                }
+            };
+            fakeReceipt.content[events[i].getId()]['m.read'][events[i].sender.userId] = {
+                ts: events[i].getTs()
+            };
+            this.addReceipt(new MatrixEvent(fakeReceipt));
+        }
+
+        this.emit("Room.timeline", events[i], this, Boolean(toStartOfTimeline), false);
     }
 };
 
@@ -260,6 +279,26 @@ Room.prototype.addEvents = function(events, duplicateStrategy) {
     }
 };
 
+/**
+ * Removes events from this room.
+ * @param {String} event_ids A list of event_ids to remove.
+ */
+Room.prototype.removeEvents = function(event_ids) {
+    for (var i = 0; i < event_ids.length; ++i) {
+        // NB. we supply reverse to search from the end,
+        // on the assumption that recents events are much
+        // more likley to be removed than older ones.
+        var removed = utils.removeElement(
+            this.timeline, function(e) {
+                return e.getId() == event_ids[i];
+            }, true
+        );
+        if (removed !== false) {
+            this.emit("Room.timeline", removed, this, undefined, true);
+        }
+    }
+};
+
 /**
  * Recalculate various aspects of the room, including the room name and
  * room summary. Call this any time the room's current state is modified.
@@ -513,6 +552,7 @@ module.exports = Room;
  * @param {MatrixEvent} event The matrix event which caused this event to fire.
  * @param {Room} room The room whose Room.timeline was updated.
  * @param {boolean} toStartOfTimeline True if this event was added to the start
+ * @param {boolean} removed True if this event has just been removed from the timeline
  * (beginning; oldest) of the timeline e.g. due to pagination.
  * @example
  * matrixClient.on("Room.timeline", function(event, room, toStartOfTimeline){

lib/utils.js

@@ -155,16 +155,18 @@ module.exports.removeElement = function(array, fn, reverse) {
     if (reverse) {
         for (i = array.length - 1; i >= 0; i--) {
             if (fn(array[i], i, array)) {
+                var removed = array[i];
                 array.splice(i, 1);
-                return true;
+                return removed;
             }
         }
     }
     else {
         for (i = 0; i < array.length; i++) {
             if (fn(array[i], i, array)) {
+                var removed = array[i];
                 array.splice(i, 1);
-                return true;
+                return removed;
             }
         }
     }