Added ISelfUser.ModifyStatusAsync

src/Discord.Net/API/DiscordAPIClient.cs

@@ -394,6 +394,15 @@ namespace Discord.API
         {
             await SendGatewayAsync(GatewayOpCode.Heartbeat, lastSeq, options: options).ConfigureAwait(false);
         }
+        public async Task SendStatusUpdateAsync(long? idleSince, Game game, RequestOptions options = null)
+        {
+            var args = new StatusUpdateParams
+            {
+                IdleSince = idleSince,
+                Game = game
+            };
+            await SendGatewayAsync(GatewayOpCode.StatusUpdate, args, options: options).ConfigureAwait(false);
+        }
         public async Task SendRequestMembersAsync(IEnumerable<ulong> guildIds, RequestOptions options = null)
         {
             await SendGatewayAsync(GatewayOpCode.RequestGuildMembers, new RequestMembersParams { GuildIds = guildIds, Query = "", Limit = 0 }, options: options).ConfigureAwait(false);

src/Discord.Net/API/Gateway/StatusUpdateParams.cs

@@ -0,0 +1,12 @@
+using Newtonsoft.Json;
+
+namespace Discord.API.Gateway
+{
+    public class StatusUpdateParams
+    {
+        [JsonProperty("idle_since"), Int53]
+        public long? IdleSince { get; set; }
+        [JsonProperty("game")]
+        public Game Game { get; set; }
+    }
+}

src/Discord.Net/API/Rest/ModifyPresenceParams.cs

@@ -0,0 +1,8 @@
+namespace Discord.API.Rest
+{
+    public class ModifyPresenceParams
+    {
+        public Optional<UserStatus> Status { get; set; }
+        public Optional<Discord.Game> Game { get; set; }
+    }
+}

src/Discord.Net/Entities/Users/ISelfUser.cs

@@ -14,5 +14,6 @@ namespace Discord
         bool IsMfaEnabled { get; }
 
         Task ModifyAsync(Action<ModifyCurrentUserParams> func);
+        Task ModifyStatusAsync(Action<ModifyPresenceParams> func);
     }
 }

src/Discord.Net/Entities/Users/SelfUser.cs

@@ -6,11 +6,18 @@ using Model = Discord.API.User;
 namespace Discord
 {
     internal class SelfUser : User, ISelfUser
-    {        
+    {
+        private long _idleSince;
+        private UserStatus _status;
+        private Game _game;
+
         public string Email { get; private set; }
         public bool IsVerified { get; private set; }
         public bool IsMfaEnabled { get; private set; }
 
+        public override UserStatus Status => _status;
+        public override Game Game => _game;
+
         public override DiscordClient Discord { get; }
 
         public SelfUser(DiscordClient discord, Model model)
@@ -49,5 +56,27 @@ namespace Discord
             var model = await Discord.ApiClient.ModifySelfAsync(args).ConfigureAwait(false);
             Update(model, UpdateSource.Rest);
         }
+        public async Task ModifyStatusAsync(Action<ModifyPresenceParams> func)
+        {
+            if (func == null) throw new NullReferenceException(nameof(func));
+            
+            var args = new ModifyPresenceParams();
+            func(args);
+
+            var game = args.Game.GetValueOrDefault(_game);
+            var status = args.Status.GetValueOrDefault(_status);
+
+            long idleSince = _idleSince;
+            if (status == UserStatus.Idle && _status != UserStatus.Idle)
+                idleSince = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+            var apiGame = new API.Game { Name = game.Name, StreamType = game.StreamType, StreamUrl = game.StreamUrl };
+
+            await Discord.ApiClient.SendStatusUpdateAsync(status == UserStatus.Idle ? _idleSince : (long?)null, apiGame).ConfigureAwait(false);
+            
+            //Save values
+            _idleSince = idleSince;
+            _game = game;
+            _status = status;
+        }
     }
 }