Support Discord game invites in multiplayer lobbies

osu.Desktop/DiscordRichPresence.cs

@@ -5,14 +5,18 @@
 using System.Text;
 using DiscordRPC;
 using DiscordRPC.Message;
+using Newtonsoft.Json;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Logging;
+using osu.Game;
 using osu.Game.Configuration;
 using osu.Game.Extensions;
 using osu.Game.Online.API;
 using osu.Game.Online.API.Requests.Responses;
+using osu.Game.Online.Multiplayer;
+using osu.Game.Online.Rooms;
 using osu.Game.Rulesets;
 using osu.Game.Users;
 using LogLevel = osu.Framework.Logging.LogLevel;
@@ -33,14 +37,25 @@ internal partial class DiscordRichPresence : Component
         [Resolved]
         private IAPIProvider api { get; set; } = null!;
 
+        [Resolved]
+        private OsuGame game { get; set; } = null!;
+
+        [Resolved]
+        private MultiplayerClient multiplayerClient { get; set; } = null!;
+
         private readonly IBindable<UserStatus?> status = new Bindable<UserStatus?>();
         private readonly IBindable<UserActivity> activity = new Bindable<UserActivity>();
 
         private readonly Bindable<DiscordRichPresenceMode> privacyMode = new Bindable<DiscordRichPresenceMode>();
 
         private readonly RichPresence presence = new RichPresence
         {
-            Assets = new Assets { LargeImageKey = "osu_logo_lazer", }
+            Assets = new Assets { LargeImageKey = "osu_logo_lazer" },
+            Secrets = new Secrets
+            {
+                JoinSecret = null,
+                SpectateSecret = null,
+            },
         };
 
         [BackgroundDependencyLoader]
@@ -52,8 +67,12 @@ private void load(OsuConfigManager config)
             };
 
             client.OnReady += onReady;
+            client.OnError += (_, e) => Logger.Log($"An error occurred with Discord RPC Client: {e.Code} {e.Message}", LoggingTarget.Network, LogLevel.Error);
 
-            client.OnError += (_, e) => Logger.Log($"An error occurred with Discord RPC Client: {e.Code} {e.Message}", LoggingTarget.Network);
+            // A URI scheme is required to support game invitations, as well as informing Discord of the game executable path to support launching the game when a user clicks on join/spectate.
+            client.RegisterUriScheme();
+            client.Subscribe(EventType.Join);
+            client.OnJoin += onJoin;
 
             config.BindWith(OsuSetting.DiscordRichPresence, privacyMode);
 
@@ -114,6 +133,34 @@ private void updateStatus()
                 {
                     presence.Buttons = null;
                 }
+
+                if (!hideIdentifiableInformation && multiplayerClient.Room != null)
+                {
+                    MultiplayerRoom room = multiplayerClient.Room;
+                    presence.Party = new Party
+                    {
+                        Privacy = string.IsNullOrEmpty(room.Settings.Password) ? Party.PrivacySetting.Public : Party.PrivacySetting.Private,
+                        ID = room.RoomID.ToString(),
+                        // technically lobbies can have infinite users, but Discord needs this to be set to something.
+                        // 1024 just happens to look nice.
+                        // https://discord.com/channels/188630481301012481/188630652340404224/1212967974793642034
+                        Max = 1024,
+                        Size = room.Users.Count,
+                    };
+
+                    RoomSecret roomSecret = new RoomSecret
+                    {
+                        RoomID = room.RoomID,
+                        Password = room.Settings.Password,
+                    };
+
+                    presence.Secrets.JoinSecret = JsonConvert.SerializeObject(roomSecret);
+                }
+                else
+                {
+                    presence.Party = null;
+                    presence.Secrets.JoinSecret = null;
+                }
             }
             else
             {
@@ -139,9 +186,32 @@ private void updateStatus()
             client.SetPresence(presence);
         }
 
+        private void onJoin(object sender, JoinMessage args)
+        {
+            game.Window?.Raise();
+
+            Logger.Log($"Received room secret from Discord RPC Client: \"{args.Secret}\"", LoggingTarget.Network, LogLevel.Debug);
+
+            // Stable and lazer share the same Discord client ID, meaning they can accept join requests from each other.
+            // Since they aren't compatible in multi, see if stable's format is being used and log to avoid confusion.
+            if (args.Secret[0] != '{' || !tryParseRoomSecret(args.Secret, out long roomId, out string? password))
+            {
+                Logger.Log("Could not join multiplayer room, invitation is invalid or incompatible.", LoggingTarget.Network, LogLevel.Important);
+                return;
+            }
+
+            var request = new GetRoomRequest(roomId);
+            request.Success += room => Schedule(() =>
+            {
+                game.PresentMultiplayerMatch(room, password);
+            });
+            request.Failure += _ => Logger.Log($"Could not join multiplayer room, room could not be found (room ID: {roomId}).", LoggingTarget.Network, LogLevel.Important);
+            api.Queue(request);
+        }
+
         private static readonly int ellipsis_length = Encoding.UTF8.GetByteCount(new[] { '…' });
 
-        private string truncate(string str)
+        private static string truncate(string str)
         {
             if (Encoding.UTF8.GetByteCount(str) <= 128)
                 return str;
@@ -160,7 +230,31 @@ private string truncate(string str)
             });
         }
 
-        private int? getBeatmapID(UserActivity activity)
+        private static bool tryParseRoomSecret(string secretJson, out long roomId, out string? password)
+        {
+            roomId = 0;
+            password = null;
+
+            RoomSecret? roomSecret;
+
+            try
+            {
+                roomSecret = JsonConvert.DeserializeObject<RoomSecret>(secretJson);
+            }
+            catch
+            {
+                return false;
+            }
+
+            if (roomSecret == null) return false;
+
+            roomId = roomSecret.RoomID;
+            password = roomSecret.Password;
+
+            return true;
+        }
+
+        private static int? getBeatmapID(UserActivity activity)
         {
             switch (activity)
             {
@@ -179,5 +273,14 @@ protected override void Dispose(bool isDisposing)
             client.Dispose();
             base.Dispose(isDisposing);
         }
+
+        private class RoomSecret
+        {
+            [JsonProperty(@"roomId", Required = Required.Always)]
+            public long RoomID { get; set; }
+
+            [JsonProperty(@"password", Required = Required.AllowNull)]
+            public string? Password { get; set; }
+        }
     }
 }