From 2c5cad71ee8155a16273a7fa3a9d159014abd947 Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Tue, 10 Jul 2018 17:17:27 +0200
Subject: [PATCH] prototype support for lazily loading members in matrixclient

---
 src/base-apis.js   | 12 ++++++++++++
 src/client.js      | 14 ++++++++++++++
 src/models/room.js | 18 ++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/src/base-apis.js b/src/base-apis.js
index bf2381790..921bec527 100644
--- a/src/base-apis.js
+++ b/src/base-apis.js
@@ -417,6 +417,18 @@ MatrixBaseApis.prototype.roomState = function(roomId, callback) {
     return this._http.authedRequest(callback, "GET", path);
 };
 
+/**
+ * @param {string} roomId
+ * @param {module:client.callback} callback Optional.
+ * @return {module:client.Promise} Resolves: TODO
+ * @return {module:http-api.MatrixError} Rejects: with an error response.
+ */
+MatrixBaseApis.prototype.joinedMembers = function(roomId, callback) {
+    const path = utils.encodeUri("/rooms/$roomId/joined_members", {$roomId: roomId});
+    return this._http.authedRequest(callback, "GET", path);
+};
+
+
 /**
  * @param {string} groupId
  * @return {module:client.Promise} Resolves: Group summary object
diff --git a/src/client.js b/src/client.js
index ab8c79b5f..93d837a4b 100644
--- a/src/client.js
+++ b/src/client.js
@@ -757,6 +757,20 @@ MatrixClient.prototype.getRoom = function(roomId) {
     return this.store.getRoom(roomId);
 };
 
+/**
+ * Preloads the member list for the given room id,
+ * in case lazy loading of memberships is in use.
+ * @param {string} roomId The room ID
+ */
+MatrixClient.prototype.loadRoomMembersIfNeeded = function(roomId) {
+    const room = this.getRoom(roomId);
+    if (!room || !room.membersNeedLoading()) {
+        return;
+    }
+    const membersPromise = this.joinedMembers(roomId);
+    room.setLazilyLoadedMembers(membersPromise);
+}
+
 /**
  * Retrieve all known rooms.
  * @return {Room[]} A list of rooms, or an empty list if there is no data store.
diff --git a/src/models/room.js b/src/models/room.js
index 7e01eab64..0141c164c 100644
--- a/src/models/room.js
+++ b/src/models/room.js
@@ -171,7 +171,10 @@ function Room(roomId, opts) {
 
     // read by megolm; boolean value - null indicates "use global value"
     this._blacklistUnverifiedDevices = null;
+    // in case of lazy loading, to keep track of loading state
+    this._membersNeedLoading = true;
 }
+
 utils.inherits(Room, EventEmitter);
 
 /**
@@ -212,7 +215,22 @@ Room.prototype.getPendingEvents = function() {
 Room.prototype.getLiveTimeline = function() {
     return this.getUnfilteredTimelineSet().getLiveTimeline();
 };
+/**
+ * Get the lazy loading state, whether loading is needed or not.
+ */
+Room.prototype.membersNeedLoading = function() {
+    return this._membersNeedLoading;
+}
 
+/**
+ * 
+ */
+Room.prototype.setLazilyLoadedMembers = async function(joinedMembersPromise) {
+    this._membersNeedLoading = false;
+    const members = await joinedMembersPromise;
+    this.currentState.setJoinedMembers(members.joined);    
+    //for all timelines > room state, call setJoinedMembers?
+}
 
 /**
  * Reset the live timeline of all timelineSets, and start new ones.