From ef77c6f989436d8dfe42c46dff78d371ec647098 Mon Sep 17 00:00:00 2001
From: Kegan Dougal <kegan@matrix.org>
Date: Tue, 23 Jun 2015 10:18:13 +0100
Subject: [PATCH] Sync room state when another device joins a room.

---
 examples/node/app.js |  4 ++--
 lib/client.js        | 20 +++++++++++++++-----
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/examples/node/app.js b/examples/node/app.js
index ed512b563..fed06ccf7 100644
--- a/examples/node/app.js
+++ b/examples/node/app.js
@@ -23,7 +23,7 @@ var rl = readline.createInterface({
     terminal: false
 });
 rl.on('line', function(line) {
-    if (line.indexOf("/enter ") === 0 && !viewingRoom) {
+    if (line.indexOf("/join ") === 0 && !viewingRoom) {
         var roomIndex = line.split(" ")[1];
         viewingRoom = roomList[roomIndex];
         if (viewingRoom.getMember(myUserId).membership === "invite") {
@@ -103,7 +103,7 @@ function printHelp() {
     console.log("Global commands:");
     console.log("  '/help' : Show this help.");
     console.log("Room list index commands:");
-    console.log("  '/enter <index>' Enter a room, e.g. '/enter 5'");
+    console.log("  '/join <index>' Join a room, e.g. '/join 5'");
     console.log("Room commands:");
     console.log("  '/exit' Return to the room list index.");
     console.log("  '/members' Show the room member list.");
diff --git a/lib/client.js b/lib/client.js
index 08e53cc40..88d8da420 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -67,6 +67,9 @@ function MatrixClient(opts) {
         userId: (opts.userId || null)
     };
     this._http = new httpApi.MatrixHttpApi(httpOpts);
+    this._syncingRooms = {
+        // room_id: Promise
+    };
 }
 utils.inherits(MatrixClient, EventEmitter);
 
@@ -1084,9 +1087,9 @@ function _pollForEvents(client) {
                     isBrandNewRoom = true;
                 }
 
-                //var wasJoined = room.hasMembershipState(
-                //    self.credentials.userId, "join"
-                //);
+                var wasJoined = room.hasMembershipState(
+                    self.credentials.userId, "join"
+                );
 
                 room.addEvents(roomIdToEvents[roomId], "replace");
                 room.recalculate(self.credentials.userId);
@@ -1097,7 +1100,7 @@ function _pollForEvents(client) {
                     self.store.storeRoom(room);
                     self.emit("Room", room);
                 }
-                /* TODO invite->join trigger roominitialsync
+
                 var justJoined = room.hasMembershipState(
                     self.credentials.userId, "join"
                 );
@@ -1106,7 +1109,7 @@ function _pollForEvents(client) {
                     // we've just transitioned into a join state for this room,
                     // so sync state.
                     _syncRoom(self, room);
-                } */
+                }
             });
         }
         if (data) {
@@ -1127,15 +1130,22 @@ function _pollForEvents(client) {
 }
 
 function _syncRoom(client, room) {
+    if (client._syncingRooms[room.roomId]) {
+        return client._syncingRooms[room.roomId];
+    }
     var defer = q.defer();
+    client._syncingRooms[room.roomId] = defer.promise;
     client.roomInitialSync(room.roomId, 8).done(function(res) {
+        room.timeline = []; // blow away any previous messages.
         _processRoomEvents(room, res.state, res.messages);
         room.recalculate(client.credentials.userId);
         client.store.storeRoom(room);
         client.emit("Room", room);
         defer.resolve(room);
+        client._syncingRooms[room.roomId] = undefined;
     }, function(err) {
         defer.reject(err);
+        client._syncingRooms[room.roomId] = undefined;
     });
     return defer.promise;
 }