Handle redactions (both live and historic).

lib/models/room.js

@@ -35,6 +35,7 @@ function Room(roomId, storageToken) {
     this.currentState = new RoomState(roomId);
     this.summary = null;
     this.storageToken = storageToken;
+    this._redactions = [];
 }
 utils.inherits(Room, EventEmitter);
 
@@ -94,6 +95,10 @@ utils.inherits(Room, EventEmitter);
 Room.prototype.addEventsToTimeline = function(events, toStartOfTimeline) {
     var stateContext = toStartOfTimeline ? this.oldState : this.currentState;
     for (var i = 0; i < events.length; i++) {
+        if (toStartOfTimeline && this._redactions.indexOf(events[i].getId()) >= 0) {
+            continue; // do not add the redacted event.
+        }
+
         setEventMetadata(events[i], stateContext, toStartOfTimeline);
         // modify state
         if (events[i].isState()) {
@@ -105,6 +110,20 @@ Room.prototype.addEventsToTimeline = function(events, toStartOfTimeline) {
                 setEventMetadata(events[i], stateContext, toStartOfTimeline);
             }
         }
+        if (events[i].getType() === "m.room.redaction") {
+            // try to remove the element
+            var removed = utils.removeElement(this.timeline, function(e) {
+                return e.getId() === events[i].event.redacts
+            }, true);
+            if (!removed && toStartOfTimeline) {
+                // redactions will trickle in BEFORE the event redacted so make
+                // a note of the redacted event; we'll check it later.
+                this._redactions.push(events[i].event.redacts);
+            }
+            // NB: We continue to add the redaction event to the timeline so clients
+            // can say "so and so redacted an event" if they wish to.
+        }
+
         // TODO: pass through filter to see if this should be added to the timeline.
         if (toStartOfTimeline) {
             this.timeline.unshift(events[i]);

lib/utils.js

@@ -148,6 +148,7 @@ module.exports.findElement = function(array, fn, reverse) {
  * function signature <code>fn(element, index, array)</code>. Return true to
  * remove this element and break.
  * @param {boolean} reverse True to search in reverse order.
+ * @return True if an element was removed.
  */
 module.exports.removeElement = function(array, fn, reverse) {
     var i;
@@ -155,17 +156,19 @@ module.exports.removeElement = function(array, fn, reverse) {
         for (i = array.length - 1; i >= 0; i--) {
             if (fn(array[i], i, array)) {
                 array.splice(i, 1);
-                return; }
+                return true;
+            }
         }
     }
     else {
         for (i = 0; i < array.length; i++) {
             if (fn(array[i], i, array)) {
                 array.splice(i, 1);
-                return;
+                return true;
             }
         }
     }
+    return false;
 };
 
 /**