Merge pull request #80 from matrix-org/rav/keep_redactions

Keep redacted events in the timeline

lib/models/event.js

@@ -21,7 +21,6 @@ limitations under the License.
  * @module models/event
  */
 
-
 /**
  * Enum for event statuses.
  * @readonly
@@ -189,5 +188,83 @@ module.exports.MatrixEvent.prototype = {
 
     getUnsigned: function() {
         return this.event.unsigned || {};
+    },
+
+    /**
+     * Update the content of an event in the same way it would be by the server
+     * if it were redacted before it was sent to us
+     *
+     * @param {Object} the raw event causing the redaction
+     */
+    makeRedacted: function(redaction_event) {
+        if (!this.event.unsigned) {
+            this.event.unsigned = {};
         }
+        this.event.unsigned.redacted_because = redaction_event;
+
+        var key;
+        for (key in this.event) {
+            if (!this.event.hasOwnProperty(key)) { continue; }
+            if (!_REDACT_KEEP_KEY_MAP[key]) {
+                delete this.event[key];
+            }
+        }
+
+        var keeps = _REDACT_KEEP_CONTENT_MAP[this.getType()] || {};
+        for (key in this.event.content) {
+            if (!this.event.content.hasOwnProperty(key)) { continue; }
+            if (!keeps[key]) {
+                delete this.event.content[key];
+            }
+        }
+    },
+
+    /**
+     * Check if this event has been redacted
+     *
+     * @return {boolean} True if this event has been redacted
+     */
+    isRedacted: function() {
+        return Boolean(this.getUnsigned().redacted_because);
+    },
+};
+
+
+/* http://matrix.org/docs/spec/r0.0.1/client_server.html#redactions says:
+ *
+ * the server should strip off any keys not in the following list:
+ *    event_id
+ *    type
+ *    room_id
+ *    user_id
+ *    state_key
+ *    prev_state
+ *    content
+ *    [we keep 'unsigned' as well, since that is created by the local server]
+ *
+ * The content object should also be stripped of all keys, unless it is one of
+ * one of the following event types:
+ *    m.room.member allows key membership
+ *    m.room.create allows key creator
+ *    m.room.join_rules allows key join_rule
+ *    m.room.power_levels allows keys ban, events, events_default, kick,
+ *        redact, state_default, users, users_default.
+ *    m.room.aliases allows key aliases
+ */
+// a map giving the keys we keep when an event is redacted
+var _REDACT_KEEP_KEY_MAP = [
+    'event_id', 'type', 'room_id', 'user_id', 'state_key', 'prev_state',
+    'content', 'unsigned',
+].reduce(function(ret, val) { ret[val] = 1; return ret; }, {});
+
+// a map from event type to the .content keys we keep when an event is redacted
+var _REDACT_KEEP_CONTENT_MAP = {
+    'm.room.member': {'membership': 1},
+    'm.room.create': {'creator': 1},
+    'm.room.join_rules': {'join_rule': 1},
+    'm.room.power_levels': {'ban': 1, 'events': 1, 'events_default': 1,
+                            'kick': 1, 'redact': 1, 'state_default': 1,
+                            'users': 1, 'users_default': 1,
+                           },
+    'm.room.aliases': {'aliases': 1},
 };

lib/models/room.js

@@ -118,7 +118,6 @@ function Room(roomId, opts) {
     this.summary = null;
     this.storageToken = opts.storageToken;
     this._opts = opts;
-    this._redactions = [];
     this._txnToEvent = {}; // Pending in-flight requests { string: MatrixEvent }
     // receipts should clobber based on receipt_type and user_id pairs hence
     // the form of this structure. This is sub-optimal for the exposed APIs
@@ -216,6 +215,22 @@ Room.prototype.getTimelineForEvent = function(eventId) {
     return (res === undefined) ? null : res;
 };
 
+/**
+ * Get an event which is stored in our timelines
+ *
+ * @param {string} eventId  event ID to look for
+ * @return {?module:models/event~MatrixEvent} the given event, or undefined if unknown
+ */
+Room.prototype.findEventById = function(eventId) {
+    var tl = this.getTimelineForEvent(eventId);
+    if (!tl) {
+        return undefined;
+    }
+    return utils.findElement(tl.getEvents(),
+                             function(ev) { return ev.getId() == eventId; });
+};
+
+
 /**
  * Get one of the notification counts for this room
  * @param {String} type The type of notification count to get. default: 'total'
@@ -523,29 +538,8 @@ Room.prototype.addEventsToTimeline = function(events, toStartOfTimeline,
 Room.prototype._addEventToTimeline = function(event, timeline, toStartOfTimeline,
                                               spliceBeforeLocalEcho) {
     var eventId = event.getId();
-
-    if (this._redactions.indexOf(eventId) >= 0) {
-        return; // do not add the redacted event.
-    }
-
-    if (event.getType() === "m.room.redaction") {
-        var redactId = event.event.redacts;
-
-        // try to remove the element
-        var removed = this.removeEvent(redactId);
-        if (!removed) {
-            // redactions will trickle in BEFORE the event redacted so make
-            // a note of the redacted event; we'll check it later.
-            this._redactions.push(event.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.
-    }
-
-    if (this._redactions.indexOf(eventId) < 0) {
     timeline.addEvent(event, toStartOfTimeline, spliceBeforeLocalEcho);
     this._eventIdToTimeline[eventId] = timeline;
-    }
 
     var data = {
         timeline: timeline,
@@ -599,6 +593,28 @@ Room.prototype._addLiveEvents = function(events) {
             }
         }
 
+
+        if (events[i].getType() === "m.room.redaction") {
+            var redactId = events[i].event.redacts;
+
+            // if we know about this event, redact its contents now.
+            var redactedEvent = this.findEventById(redactId);
+            if (redactedEvent) {
+                redactedEvent.makeRedacted(events[i]);
+                this.emit("Room.redaction", events[i], this);
+
+                // TODO: we stash user displaynames (among other things) in
+                // RoomMember objects which are then attached to other events
+                // (in the sender and target fields). We should get those
+                // RoomMember objects to update themselves when the events that
+                // they are based on are changed.
+            }
+
+            // 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. Also
+            // this may be needed to trigger an update.
+        }
+
         var spliceBeforeLocalEcho = !isLocalEcho && addLocalEchoToEnd;
 
         if (!this._eventIdToTimeline[events[i].getId()]) {
@@ -1147,6 +1163,17 @@ module.exports = Room;
  * });
  */
 
+/**
+ * Fires when an event we had previously received is redacted.
+ *
+ * (Note this is *not* fired when the redaction happens before we receive the
+ * event).
+ *
+ * @event module:client~MatrixClient#"Room.redaction"
+ * @param {MatrixEvent} event The matrix event which was redacted
+ * @param {Room} room The room containing the redacted event
+ */
+
 /**
  * Fires whenever the name of a room is updated.
  * @event module:client~MatrixClient#"Room.name"

lib/sync.js

@@ -83,7 +83,8 @@ SyncApi.prototype.createRoom = function(roomId) {
         pendingEventOrdering: this.opts.pendingEventOrdering,
         timelineSupport: client.timelineSupport,
     });
-    reEmit(client, room, ["Room.name", "Room.timeline", "Room.receipt", "Room.tags"]);
+    reEmit(client, room, ["Room.name", "Room.timeline", "Room.redaction",
+                          "Room.receipt", "Room.tags"]);
     this._registerStateListeners(room);
     return room;
 };