baseline: OpenMU upstream b5a0961 (fresh source)

src/GameServer/RemoteView/Messenger/AddToLetterListPlugIn.cs

@@ -0,0 +1,40 @@
+// <copyright file="AddToLetterListPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Interfaces;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IAddToLetterListPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.AddToLetterListPlugIn_Name), Description = nameof(PlugInResources.AddToLetterListPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("d30bea99-9d77-4182-99be-e08095c1969f")]
+public class AddToLetterListPlugIn : IAddToLetterListPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AddToLetterListPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public AddToLetterListPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask AddToLetterListAsync(LetterHeader letter, ushort newLetterIndex, bool newLetter)
+    {
+        await this._player.Connection.SendAddLetterAsync(
+            newLetterIndex,
+            letter.SenderName ?? string.Empty,
+            letter.LetterDate.ToUniversalTime().AddHours(this._player.Account?.TimeZone ?? 0).ToString("yyyy-MM-dd HH:mm:ss"),
+            letter.Subject ?? string.Empty,
+            newLetter ? AddLetter.LetterState.New : letter.ReadFlag ? AddLetter.LetterState.Read : AddLetter.LetterState.Unread)
+            .ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/ChatRoomCreatedPlugIn.cs

@@ -0,0 +1,50 @@
+// <copyright file="ChatRoomCreatedPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Net;
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Interfaces;
+using MUnique.OpenMU.Network;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IChatRoomCreatedPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.ChatRoomCreatedPlugIn_Name), Description = nameof(PlugInResources.ChatRoomCreatedPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("a7c99cb5-94f6-42ea-b6e2-2272a9a81e12")]
+public class ChatRoomCreatedPlugIn : IChatRoomCreatedPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ChatRoomCreatedPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public ChatRoomCreatedPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask ChatRoomCreatedAsync(ChatServerAuthenticationInfo authenticationInfo, string friendName, bool success)
+    {
+        var hostAddress = authenticationInfo.HostAddress;
+        if (IPAddress.TryParse(authenticationInfo.HostAddress, out var chatServerAddress)
+            && chatServerAddress.IsOnSameHost()
+            && this._player.Connection?.LocalEndPoint is IPEndPoint localEndPoint)
+        {
+            hostAddress = localEndPoint.Address.ToString();
+        }
+
+        await this._player.Connection.SendChatRoomConnectionInfoAsync(
+            hostAddress,
+            authenticationInfo.RoomId,
+            uint.Parse(authenticationInfo.AuthenticationToken),
+            friendName,
+            success)
+            .ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/FriendAddedPlugIn.cs

@@ -0,0 +1,33 @@
+// <copyright file="FriendAddedPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IFriendAddedPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.FriendAddedPlugIn_Name), Description = nameof(PlugInResources.FriendAddedPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("7edba5ed-eec5-4aa7-b302-418444868841")]
+public class FriendAddedPlugIn : IFriendAddedPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="FriendAddedPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public FriendAddedPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask FriendAddedAsync(string friendName)
+    {
+        await this._player.Connection.SendFriendAddedAsync(friendName).ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/FriendDeletedPlugIn.cs

@@ -0,0 +1,33 @@
+// <copyright file="FriendDeletedPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IFriendDeletedPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.FriendDeletedPlugIn_Name), Description = nameof(PlugInResources.FriendDeletedPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("3f6f86ec-ffe8-4fa7-82c3-4a743fab7157")]
+public class FriendDeletedPlugIn : IFriendDeletedPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="FriendDeletedPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public FriendDeletedPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask FriendDeletedAsync(string deletedFriend)
+    {
+        await this._player.Connection.SendFriendDeletedAsync(deletedFriend).ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/FriendStateUpdatePlugIn.cs

@@ -0,0 +1,33 @@
+// <copyright file="FriendStateUpdatePlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IFriendStateUpdatePlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.FriendStateUpdatePlugIn_Name), Description = nameof(PlugInResources.FriendStateUpdatePlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("1ed98d6a-7917-4209-bd03-e8a966b99688")]
+public class FriendStateUpdatePlugIn : IFriendStateUpdatePlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="FriendStateUpdatePlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public FriendStateUpdatePlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask FriendStateUpdateAsync(string friend, int serverId)
+    {
+        await this._player.Connection.SendFriendOnlineStateUpdateAsync(friend, (byte)serverId).ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/InitializeMessengerPlugIn.cs

@@ -0,0 +1,77 @@
+// <copyright file="InitializeMessengerPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Interfaces;
+using MUnique.OpenMU.Network;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IInitializeMessengerPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.InitializeMessengerPlugIn_Name), Description = nameof(PlugInResources.InitializeMessengerPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("cb079c23-e90c-473d-87ae-317937158924")]
+public class InitializeMessengerPlugIn : IInitializeMessengerPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="InitializeMessengerPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public InitializeMessengerPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask InitializeMessengerAsync(MessengerInitializationData data, int maxLetters)
+    {
+        var connection = this._player.Connection;
+        if (connection is null || this._player.SelectedCharacter is null)
+        {
+            return;
+        }
+
+        int Write()
+        {
+            var friendList = data.Friends;
+            var size = MessengerInitializationRef.GetRequiredSize(friendList.Count);
+            var span = connection.Output.GetSpan(size)[..size];
+            var message = new MessengerInitializationRef(span)
+            {
+                FriendCount = (byte)friendList.Count,
+                LetterCount = (byte)this._player.SelectedCharacter.Letters.Count,
+                MaximumLetterCount = (byte)maxLetters,
+            };
+
+            int i = 0;
+            foreach (var friend in friendList)
+            {
+                var friendBlock = message[i];
+                friendBlock.Name = friend;
+                friendBlock.ServerId = (byte)SpecialServerId.Offline;
+                i++;
+            }
+
+            return size;
+        }
+
+        await connection.SendAsync(Write).ConfigureAwait(false);
+
+        foreach (var requesterName in data.OpenFriendRequests)
+        {
+            await this._player.InvokeViewPlugInAsync<IShowFriendRequestPlugIn>(p => p.ShowFriendRequestAsync(requesterName)).ConfigureAwait(false);
+        }
+
+        var letters = this._player.SelectedCharacter.Letters;
+        for (ushort l = 0; l < letters.Count; l++)
+        {
+            await this._player.InvokeViewPlugInAsync<IAddToLetterListPlugIn>(p => p.AddToLetterListAsync(letters[l], l, false)).ConfigureAwait(false);
+        }
+    }
+}

src/GameServer/RemoteView/Messenger/LetterDeletedPlugIn.cs

@@ -0,0 +1,33 @@
+// <copyright file="LetterDeletedPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="ILetterDeletedPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.LetterDeletedPlugIn_Name), Description = nameof(PlugInResources.LetterDeletedPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("3bcd507e-cb61-4b25-a208-4ee264f4793e")]
+public class LetterDeletedPlugIn : ILetterDeletedPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="LetterDeletedPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public LetterDeletedPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask LetterDeletedAsync(ushort letterIndex)
+    {
+        await this._player.Connection.SendRemoveLetterAsync(letterIndex).ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/LetterSendResultPlugIn.cs

@@ -0,0 +1,47 @@
+// <copyright file="LetterSendResultPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="ILetterSendResultPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.LetterSendResultPlugIn_Name), Description = nameof(PlugInResources.LetterSendResultPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("c67cad23-20ba-4cd7-ba4e-b672beed427c")]
+public class LetterSendResultPlugIn : ILetterSendResultPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="LetterSendResultPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public LetterSendResultPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask LetterSendResultAsync(LetterSendSuccess success, uint letterId)
+    {
+        await this._player.Connection.SendLetterSendResponseAsync(letterId, Convert(success)).ConfigureAwait(false);
+    }
+
+    private static LetterSendResponse.LetterSendRequestResult Convert(LetterSendSuccess success)
+    {
+        return success switch
+        {
+            LetterSendSuccess.TryAgain => LetterSendResponse.LetterSendRequestResult.TryAgain,
+            LetterSendSuccess.Success => LetterSendResponse.LetterSendRequestResult.Success,
+            LetterSendSuccess.MailboxFull => LetterSendResponse.LetterSendRequestResult.MailboxFull,
+            LetterSendSuccess.ReceiverNotExists => LetterSendResponse.LetterSendRequestResult.ReceiverNotExists,
+            LetterSendSuccess.CantSendToYourself => LetterSendResponse.LetterSendRequestResult.CantSendToYourself,
+            LetterSendSuccess.NotEnoughMoney => LetterSendResponse.LetterSendRequestResult.NotEnoughMoney,
+            _ => throw new ArgumentException($"Unhandled case {success}."),
+        };
+    }
+}

src/GameServer/RemoteView/Messenger/ShowFriendInvitationResultPlugIn.cs

@@ -0,0 +1,33 @@
+// <copyright file="ShowFriendInvitationResultPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IShowFriendInvitationResultPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.ShowFriendInvitationResultPlugIn_Name), Description = nameof(PlugInResources.ShowFriendInvitationResultPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("8df329bd-88da-423c-8f85-173180ab8601")]
+public class ShowFriendInvitationResultPlugIn : IShowFriendInvitationResultPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ShowFriendInvitationResultPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public ShowFriendInvitationResultPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask ShowFriendInvitationResultAsync(bool success, uint requestId)
+    {
+        await this._player.Connection.SendFriendInvitationResultAsync(success, requestId).ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/ShowFriendRequestPlugIn.cs

@@ -0,0 +1,33 @@
+// <copyright file="ShowFriendRequestPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IShowFriendRequestPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.ShowFriendRequestPlugIn_Name), Description = nameof(PlugInResources.ShowFriendRequestPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("efb8b51b-181a-4a7d-b5a4-34c0dbd41748")]
+public class ShowFriendRequestPlugIn : IShowFriendRequestPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ShowFriendRequestPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public ShowFriendRequestPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask ShowFriendRequestAsync(string requester)
+    {
+        await this._player.Connection.SendFriendRequestAsync(requester).ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/ShowLetterExtendedPlugIn.cs

@@ -0,0 +1,65 @@
+// <copyright file="ShowLetterExtendedPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.DataModel.Entities;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.Network.PlugIns;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IShowLetterPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.ShowLetterExtendedPlugIn_Name), Description = nameof(PlugInResources.ShowLetterExtendedPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("9FC6D771-FCCE-4780-B68E-5FBFF3FE1EB0")]
+[MinimumClient(106, 3, ClientLanguage.Invariant)]
+public class ShowLetterExtendedPlugIn : IShowLetterPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ShowLetterExtendedPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public ShowLetterExtendedPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask ShowLetterAsync(LetterBody letter)
+    {
+        var connection = this._player.Connection;
+        if (connection is null || this._player.SelectedCharacter is null)
+        {
+            return;
+        }
+
+        var appearanceSerializer = this._player.AppearanceSerializer;
+        var letterIndex = this._player.SelectedCharacter.Letters.IndexOf(letter.Header!);
+        int Write()
+        {
+            var size = OpenLetterExtendedRef.GetRequiredSize(letter.Message);
+            var span = connection.Output.GetSpan(size)[..size];
+            var result = new OpenLetterExtendedRef(span)
+            {
+                LetterIndex = (ushort)letterIndex,
+                Animation = letter.Animation,
+                Rotation = letter.Rotation,
+                Message = letter.Message,
+            };
+
+            if (letter.SenderAppearance is not null)
+            {
+                appearanceSerializer.WriteAppearanceData(result.SenderAppearance, letter.SenderAppearance, false);
+            }
+
+            return size;
+        }
+
+        await connection.SendAsync(Write).ConfigureAwait(false);
+    }
+}

src/GameServer/RemoteView/Messenger/ShowLetterPlugIn.cs

@@ -0,0 +1,65 @@
+// <copyright file="ShowLetterPlugIn.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.GameServer.RemoteView.Messenger;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.DataModel.Entities;
+using MUnique.OpenMU.GameLogic.Views.Messenger;
+using MUnique.OpenMU.Network;
+using MUnique.OpenMU.Network.Packets.ServerToClient;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// The default implementation of the <see cref="IShowLetterPlugIn"/> which is forwarding everything to the game client with specific data packets.
+/// </summary>
+[PlugIn]
+[Display(Name = nameof(PlugInResources.ShowLetterPlugIn_Name), Description = nameof(PlugInResources.ShowLetterPlugIn_Description), ResourceType = typeof(PlugInResources))]
+[Guid("6ce73080-6916-465f-b6d1-34641687ded3")]
+public class ShowLetterPlugIn : IShowLetterPlugIn
+{
+    private readonly RemotePlayer _player;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ShowLetterPlugIn"/> class.
+    /// </summary>
+    /// <param name="player">The player.</param>
+    public ShowLetterPlugIn(RemotePlayer player) => this._player = player;
+
+    /// <inheritdoc/>
+    public async ValueTask ShowLetterAsync(LetterBody letter)
+    {
+        var connection = this._player.Connection;
+        if (connection is null || this._player.SelectedCharacter is null)
+        {
+            return;
+        }
+
+        var appearanceSerializer = this._player.AppearanceSerializer;
+        var letterIndex = this._player.SelectedCharacter.Letters.IndexOf(letter.Header!);
+        int Write()
+        {
+            var size = OpenLetterRef.GetRequiredSize(letter.Message);
+            var span = connection.Output.GetSpan(size)[..size];
+            var result = new OpenLetterRef(span)
+            {
+                LetterIndex = (ushort)letterIndex,
+                MessageSize = (ushort)Encoding.UTF8.GetByteCount(letter.Message),
+                Animation = letter.Animation,
+                Rotation = letter.Rotation,
+                Message = letter.Message,
+            };
+
+            // TODO: Somewhere is the GM-Sign defined.
+            if (letter.SenderAppearance is not null)
+            {
+                appearanceSerializer.WriteAppearanceData(result.SenderAppearance, letter.SenderAppearance, false);
+            }
+
+            return size;
+        }
+
+        await connection.SendAsync(Write).ConfigureAwait(false);
+    }
+}