Add better support for invisible users

src/Discord.Net.WebSocket/DiscordSocketClient.cs

@@ -900,7 +900,7 @@ namespace Discord.WebSocket
                                     var channel = State.GetChannel(data.ChannelId) as SocketGroupChannel;
                                     if (channel != null)
                                     {
-                                        var user = channel.AddUser(data.User);
+                                        var user = channel.GetOrAddUser(data.User);
                                         await TimedInvokeAsync(_recipientAddedEvent, nameof(RecipientAdded), user).ConfigureAwait(false);
                                     }
                                     else
@@ -1109,20 +1109,20 @@ namespace Discord.WebSocket
                                         else
                                             author = (channel as SocketChannel).GetUser(data.Author.Value.Id);
 
-                                        if (author != null)
-                                        {
-                                            var msg = SocketMessage.Create(this, State, author, channel, data);
-                                            SocketChannelHelper.AddMessage(channel, this, msg);
-                                            await TimedInvokeAsync(_messageReceivedEvent, nameof(MessageReceived), msg).ConfigureAwait(false);
-                                        }
-                                        else
+                                        if (author == null)
                                         {
                                             if (guild != null)
-                                                await UnknownGuildUserAsync(type, data.Author.Value.Id, guild.Id).ConfigureAwait(false);
+                                                author = guild.AddOrUpdateUser(data.Author.Value); //User has no guild-specific data
+                                            else if (channel is SocketGroupChannel)
+                                                author = (channel as SocketGroupChannel).GetOrAddUser(data.Author.Value);
                                             else
                                                 await UnknownChannelUserAsync(type, data.Author.Value.Id, channel.Id).ConfigureAwait(false);
                                             return;
                                         }
+
+                                        var msg = SocketMessage.Create(this, State, author, channel, data);
+                                        SocketChannelHelper.AddMessage(channel, this, msg);
+                                        await TimedInvokeAsync(_messageReceivedEvent, nameof(MessageReceived), msg).ConfigureAwait(false);
                                     }
                                     else
                                     {

src/Discord.Net.WebSocket/Entities/Channels/SocketGroupChannel.cs

@@ -125,7 +125,7 @@ namespace Discord.WebSocket
                 return user;
             return null;
         }
-        internal SocketGroupUser AddUser(UserModel model)
+        internal SocketGroupUser GetOrAddUser(UserModel model)
         {
             SocketGroupUser user;
             if (_users.TryGetValue(model.Id, out user))

src/Discord.Net.WebSocket/Entities/Guilds/SocketGuild.cs

@@ -16,6 +16,7 @@ using MemberModel = Discord.API.GuildMember;
 using Model = Discord.API.Guild;
 using PresenceModel = Discord.API.Presence;
 using RoleModel = Discord.API.Role;
+using UserModel = Discord.API.User;
 using VoiceStateModel = Discord.API.VoiceState;
 
 namespace Discord.WebSocket
@@ -375,6 +376,19 @@ namespace Discord.WebSocket
         public Task<int> PruneUsersAsync(int days = 30, bool simulate = false, RequestOptions options = null)
             => GuildHelper.PruneUsersAsync(this, Discord, days, simulate, options);
 
+        internal SocketGuildUser AddOrUpdateUser(UserModel model)
+        {
+            SocketGuildUser member;
+            if (_members.TryGetValue(model.Id, out member))
+                member.GlobalUser?.Update(Discord.State, model);
+            else
+            {
+                member = SocketGuildUser.Create(this, Discord.State, model);
+                _members[member.Id] = member;
+                DownloadedMemberCount++;
+            }
+            return member;
+        }
         internal SocketGuildUser AddOrUpdateUser(MemberModel model)
         {
             SocketGuildUser member;

src/Discord.Net.WebSocket/Entities/Users/SocketGuildUser.cs

@@ -6,7 +6,8 @@ using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Linq;
 using System.Threading.Tasks;
-using Model = Discord.API.GuildMember;
+using UserModel = Discord.API.User;
+using MemberModel = Discord.API.GuildMember;
 using PresenceModel = Discord.API.Presence;
 
 namespace Discord.WebSocket
@@ -69,7 +70,14 @@ namespace Discord.WebSocket
             Guild = guild;
             GlobalUser = globalUser;
         }
-        internal static SocketGuildUser Create(SocketGuild guild, ClientState state, Model model)
+        internal static SocketGuildUser Create(SocketGuild guild, ClientState state, UserModel model)
+        {
+            var entity = new SocketGuildUser(guild, guild.Discord.GetOrCreateUser(state, model));
+            entity.Update(state, model);
+            entity.UpdateRoles(new ulong[0]);
+            return entity;
+        }
+        internal static SocketGuildUser Create(SocketGuild guild, ClientState state, MemberModel model)
         {
             var entity = new SocketGuildUser(guild, guild.Discord.GetOrCreateUser(state, model.User));
             entity.Update(state, model);
@@ -81,7 +89,7 @@ namespace Discord.WebSocket
             entity.Update(state, model, false);
             return entity;
         }
-        internal void Update(ClientState state, Model model)
+        internal void Update(ClientState state, MemberModel model)
         {
             base.Update(state, model.User);
             if (model.JoinedAt.IsSpecified)