ModernUO/Projects/Server/Network/Packets/OutgoingGumpPackets.cs

/*************************************************************************
 * ModernUO                                                              *
 * Copyright (C) 2019-2020 - ModernUO Development Team                   *
 * Email: hi@modernuo.com                                                *
 * File: OutgoingGumpPackets.cs                                          *
 *                                                                       *
 * This program is free software: you can redistribute it and/or modify  *
 * it under the terms of the GNU General Public License as published by  *
 * the Free Software Foundation, either version 3 of the License, or     *
 * (at your option) any later version.                                   *
 *                                                                       *
 * You should have received a copy of the GNU General Public License     *
 * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 *************************************************************************/

using System;
using System.Buffers;
using System.IO;
using System.IO.Compression;
using System.Runtime.CompilerServices;
using Server.Collections;
using Server.Gumps;

namespace Server.Network
{
    public static class OutgoingGumpPackets
    {
        public static void SendCloseGump(this NetState ns, int typeId, int buttonId)
        {
            if (ns == null)
            {
                return;
            }

            var writer = new SpanWriter(stackalloc byte[13]);
            writer.Write((byte)0xBF); // Packet ID
            writer.Write((ushort)13);

            writer.Write((short)0x04);
            writer.Write(typeId);
            writer.Write(buttonId);

            ns.Send(writer.Span);
        }

        private static readonly byte[] _layoutBuffer = GC.AllocateUninitializedArray<byte>(0x20000);
        private static readonly byte[] _stringsBuffer = GC.AllocateUninitializedArray<byte>(0x20000);
        private static readonly byte[] _packBuffer = GC.AllocateUninitializedArray<byte>(0x20000);

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        private static void WritePacked(ReadOnlySpan<byte> span, ref SpanWriter writer)
        {
            var length = span.Length;

            if (length == 0)
            {
                writer.Write(0);
                return;
            }

            var wantLength = Zlib.MaxPackSize(length);
            var packBuffer = _packBuffer;
            byte[] rentedBuffer = null;

            if (wantLength > packBuffer.Length)
            {
                packBuffer = rentedBuffer = ArrayPool<byte>.Shared.Rent(wantLength);
            }

            var packLength = wantLength;

            var error = Zlib.Pack(packBuffer, ref packLength, span, length, ZlibQuality.Default);

            if (error != ZlibError.Okay)
            {
                Utility.PushColor(ConsoleColor.Red);
                Console.WriteLine("Core: Gump compression failed {0}", error);
                Utility.PopColor();

                writer.Write(4);
                writer.Write(0);
                return;
            }

            writer.Write(4 + packLength);
            writer.Write(length);
            writer.Write(packBuffer.AsSpan(0, packLength));

            if (rentedBuffer != null)
            {
                ArrayPool<byte>.Shared.Return(rentedBuffer);
            }
        }

        public static void SendDisplayGump(this NetState ns, Gump gump, out int switches, out int entries)
        {
            switches = 0;
            entries = 0;

            if (ns == null)
            {
                return;
            }

            var packed = ns.Unpack;

            var layoutWriter = new SpanWriter(_layoutBuffer);

            if (!gump.Draggable)
            {
                layoutWriter.Write(Gump.NoMove);
            }

            if (!gump.Closable)
            {
                layoutWriter.Write(Gump.NoClose);
            }

            if (!gump.Disposable)
            {
                layoutWriter.Write(Gump.NoDispose);
            }

            if (!gump.Resizable)
            {
                layoutWriter.Write(Gump.NoResize);
            }

            var stringsList = new OrderedHashSet<string>(11);

            foreach (var entry in gump.Entries)
            {
                entry.AppendTo(ref layoutWriter, stringsList, ref entries, ref switches);
            }

            var stringsWriter = new SpanWriter(_stringsBuffer);

            foreach (var str in stringsList)
            {
                var s = str ?? "";
                stringsWriter.Write((ushort)s.Length);
                stringsWriter.WriteBigUni(s);
            }

            int maxLength;
            if (packed)
            {
                var worstLayoutLength = Zlib.MaxPackSize(layoutWriter.BytesWritten);
                var worstStringsLength = Zlib.MaxPackSize(stringsWriter.BytesWritten);
                maxLength = 40 + worstLayoutLength + worstStringsLength;
            }
            else
            {
                maxLength = 23 + layoutWriter.BytesWritten + stringsWriter.BytesWritten;
            }

            var writer = new SpanWriter(stackalloc byte[maxLength]);
            writer.Write((byte)(packed ? 0xDD : 0xB0)); // Packet ID
            writer.Seek(2, SeekOrigin.Current);

            writer.Write(gump.Serial);
            writer.Write(gump.TypeID);
            writer.Write(gump.X);
            writer.Write(gump.Y);

            if (packed)
            {
                layoutWriter.Write((byte)0); // Layout text terminator
                WritePacked(layoutWriter.Span, ref writer);

                writer.Write(stringsList.Count);
                WritePacked(stringsWriter.Span, ref writer);
            }
            else
            {
                writer.Write((ushort)layoutWriter.BytesWritten);
                writer.Write(layoutWriter.Span);

                writer.Write((ushort)stringsList.Count);
                writer.Write(stringsWriter.Span);
            }

            writer.WritePacketLength();

            ns.Send(writer.Span);
        }

        public static void SendDisplaySignGump(this NetState ns, Serial serial, int gumpId, string unknown, string caption)
        {
            if (ns == null || !ns.GetSendBuffer(out var buffer))
            {
                return;
            }

            unknown ??= "";
            caption ??= "";

            var length = 15 + unknown.Length + caption.Length;
            var writer = new SpanWriter(stackalloc byte[length]);
            writer.Write((byte)0x8B); // Packet ID
            writer.Write((ushort)length);

            writer.Write(serial);
            writer.Write((short)gumpId);
            writer.Write((short)(unknown.Length + 1));
            writer.WriteAsciiNull(unknown);
            writer.Write((short)(caption.Length + 1));
            writer.WriteAsciiNull(caption);

            ns.Send(writer.Span);
        }
    }
}