Support Discord game invites in multiplayer lobbies

osu.Desktop/DiscordRichPresence.cs

@@ -9,10 +9,13 @@ 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;
@@ -22,6 +25,7 @@ namespace osu.Desktop
     internal partial class DiscordRichPresence : Component
     {
         private const string client_id = "367827983903490050";
+        public const string DISCORD_PROTOCOL = $"discord-{client_id}://";
 
         private DiscordRpcClient client = null!;
 
@@ -33,6 +37,12 @@ namespace osu.Desktop
         [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>();
 
@@ -40,7 +50,12 @@ namespace osu.Desktop
 
         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 +67,14 @@ namespace osu.Desktop
             };
 
             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);
+            // set up stuff for spectate/join
+            // first, we register a uri scheme for when osu! isn't running and a user clicks join/spectate
+            // the rpc library we use also happens to _require_ that we do this
+            client.RegisterUriScheme();
+            client.Subscribe(EventType.Join); // we have to explicitly tell discord to send us join events.
+            client.OnJoin += onJoin;
 
             config.BindWith(OsuSetting.DiscordRichPresence, privacyMode);
 
@@ -114,6 +135,28 @@ namespace osu.Desktop
                 {
                     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,
+                    };
+
+                    presence.Secrets.JoinSecret = $"{room.RoomID}:{room.Settings.Password}";
+                }
+                else
+                {
+                    presence.Party = null;
+                    presence.Secrets.JoinSecret = null;
+                }
             }
             else
             {
@@ -139,6 +182,22 @@ namespace osu.Desktop
             client.SetPresence(presence);
         }
 
+        private void onJoin(object sender, JoinMessage args)
+        {
+            game.Window?.Raise(); // users will expect to be brought back to osu! when joining a lobby from discord
+
+            if (!tryParseRoomSecret(args.Secret, out long roomId, out string? password))
+                Logger.Log("Failed to parse the room secret Discord gave us", LoggingTarget.Network, LogLevel.Error);
+
+            var request = new GetRoomRequest(roomId);
+            request.Success += room => Schedule(() =>
+            {
+                game.PresentMultiplayerMatch(room, password);
+            });
+            request.Failure += _ => Logger.Log("Couldn't find the room Discord gave us", LoggingTarget.Network, LogLevel.Error);
+            api.Queue(request);
+        }
+
         private static readonly int ellipsis_length = Encoding.UTF8.GetByteCount(new[] { '…' });
 
         private string truncate(string str)
@@ -160,6 +219,26 @@ namespace osu.Desktop
             });
         }
 
+        private static bool tryParseRoomSecret(ReadOnlySpan<char> secret, out long roomId, out string? password)
+        {
+            roomId = 0;
+            password = null;
+
+            int roomSecretSplitIndex = secret.IndexOf(':');
+
+            if (roomSecretSplitIndex == -1)
+                return false;
+
+            if (!long.TryParse(secret[..roomSecretSplitIndex], out roomId))
+                return false;
+
+            // just convert to string here, we're going to have to alloc it later anyways
+            password = secret[(roomSecretSplitIndex + 1)..].ToString();
+            if (password.Length == 0) password = null;
+
+            return true;
+        }
+
         private int? getBeatmapID(UserActivity activity)
         {
             switch (activity)