Fetch existing private message channels on re-joining

osu.Game/Online/API/Requests/CreateChannelRequest.cs

@@ -0,0 +1,34 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Linq;
+using System.Net.Http;
+using osu.Framework.IO.Network;
+using osu.Game.Online.API.Requests.Responses;
+using osu.Game.Online.Chat;
+
+namespace osu.Game.Online.API.Requests
+{
+    public class CreateChannelRequest : APIRequest<APIChatChannel>
+    {
+        private readonly Channel channel;
+
+        public CreateChannelRequest(Channel channel)
+        {
+            this.channel = channel;
+        }
+
+        protected override WebRequest CreateWebRequest()
+        {
+            var req = base.CreateWebRequest();
+            req.Method = HttpMethod.Post;
+
+            req.AddParameter("type", $"{ChannelType.PM}");
+            req.AddParameter("target_id", $"{channel.Users.First().Id}");
+
+            return req;
+        }
+
+        protected override string Target => @"chat/channels";
+    }
+}

osu.Game/Online/API/Requests/Responses/APIChatChannel.cs

@@ -0,0 +1,18 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using Newtonsoft.Json;
+using osu.Game.Online.Chat;
+
+namespace osu.Game.Online.API.Requests.Responses
+{
+    public class APIChatChannel
+    {
+        [JsonProperty(@"channel_id")]
+        public int? ChannelID { get; set; }
+
+        [JsonProperty(@"recent_messages")]
+        public List<Message> RecentMessages { get; set; }
+    }
+}

osu.Game/Online/Chat/Channel.cs

@@ -84,7 +84,8 @@ private long[] userIds
         public long? LastReadId;
 
         /// <summary>
-        /// Signalles if the current user joined this channel or not. Defaults to false.
+        /// Signals if the current user joined this channel or not. Defaults to false.
+        /// Note that this does not guarantee a join has completed. Check Id > 0 for confirmation.
         /// </summary>
         public Bindable<bool> Joined = new Bindable<bool>();
 

osu.Game/Online/Chat/ChannelManager.cs

@@ -86,7 +86,7 @@ public void OpenPrivateChannel(User user)
                 return;
 
             CurrentChannel.Value = JoinedChannels.FirstOrDefault(c => c.Type == ChannelType.PM && c.Users.Count == 1 && c.Users.Any(u => u.Id == user.Id))
-                                   ?? new Channel(user);
+                                   ?? JoinChannel(new Channel(user));
         }
 
         private void currentChannelChanged(ValueChangedEvent<Channel> e)
@@ -140,7 +140,7 @@ void dequeueAndRun()
                 target.AddLocalEcho(message);
 
                 // if this is a PM and the first message, we need to do a special request to create the PM channel
-                if (target.Type == ChannelType.PM && !target.Joined.Value)
+                if (target.Type == ChannelType.PM && target.Id == 0)
                 {
                     var createNewPrivateMessageRequest = new CreateNewPrivateMessageRequest(target.Users.First(), message);
 
@@ -356,26 +356,35 @@ private Channel joinChannel(Channel channel, bool fetchInitialMessages = false)
             // ensure we are joined to the channel
             if (!channel.Joined.Value)
             {
+                channel.Joined.Value = true;
+
                 switch (channel.Type)
                 {
                     case ChannelType.Multiplayer:
                         // join is implicit. happens when you join a multiplayer game.
                         // this will probably change in the future.
-                        channel.Joined.Value = true;
                         joinChannel(channel, fetchInitialMessages);
                         return channel;
 
-                    case ChannelType.Private:
-                        // can't do this yet.
+                    case ChannelType.PM:
+                        var createRequest = new CreateChannelRequest(channel);
+                        createRequest.Success += resChannel =>
+                        {
+                            if (resChannel.ChannelID.HasValue)
+                            {
+                                channel.Id = resChannel.ChannelID.Value;
+
+                                handleChannelMessages(resChannel.RecentMessages);
+                                channel.MessagesLoaded = true; // this will mark the channel as having received messages even if there were none.
+                            }
+                        };
+
+                        api.Queue(createRequest);
                         break;
 
                     default:
                         var req = new JoinChannelRequest(channel, api.LocalUser.Value);
-                        req.Success += () =>
-                        {
-                            channel.Joined.Value = true;
-                            joinChannel(channel, fetchInitialMessages);
-                        };
+                        req.Success += () => joinChannel(channel, fetchInitialMessages);
                         req.Failure += ex => LeaveChannel(channel);
                         api.Queue(req);
                         return channel;