/***************************************************************************
 *                               Compression.cs
 *                            -------------------
 *   begin                : May 1, 2002
 *   copyright            : (C) The RunUO Software Team
 *   email                : info@runuo.com
 *
 *   $Id: Compression.cs 644 2010-12-23 09:18:45Z asayre $
 *
 ***************************************************************************/

/***************************************************************************
 *
 *   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 2 of the License, or
 *   (at your option) any later version.
 *
 ***************************************************************************/

using System;
using System.IO;
using System.Runtime.InteropServices;

namespace Server.Network
{
    /// <summary>
    /// Handles outgoing packet compression for the network.
    /// </summary>
    public static class Compression
    {
        private static int[] _huffmanTable = new int[514]
		{
			0x2, 0x000,	0x5, 0x01F,	0x6, 0x022,	0x7, 0x034,	0x7, 0x075,	0x6, 0x028,	0x6, 0x03B,	0x7, 0x032,
			0x8, 0x0E0,	0x8, 0x062,	0x7, 0x056,	0x8, 0x079,	0x9, 0x19D,	0x8, 0x097,	0x6, 0x02A,	0x7, 0x057,
			0x8, 0x071,	0x8, 0x05B,	0x9, 0x1CC,	0x8, 0x0A7,	0x7, 0x025,	0x7, 0x04F,	0x8, 0x066,	0x8, 0x07D,
			0x9, 0x191,	0x9, 0x1CE,	0x7, 0x03F,	0x9, 0x090,	0x8, 0x059,	0x8, 0x07B,	0x8, 0x091,	0x8, 0x0C6,
			0x6, 0x02D,	0x9, 0x186,	0x8, 0x06F,	0x9, 0x093,	0xA, 0x1CC,	0x8, 0x05A,	0xA, 0x1AE,	0xA, 0x1C0,
			0x9, 0x148,	0x9, 0x14A,	0x9, 0x082,	0xA, 0x19F,	0x9, 0x171,	0x9, 0x120,	0x9, 0x0E7,	0xA, 0x1F3,
			0x9, 0x14B,	0x9, 0x100,	0x9, 0x190,	0x6, 0x013,	0x9, 0x161,	0x9, 0x125,	0x9, 0x133,	0x9, 0x195,
			0x9, 0x173,	0x9, 0x1CA,	0x9, 0x086,	0x9, 0x1E9,	0x9, 0x0DB,	0x9, 0x1EC,	0x9, 0x08B,	0x9, 0x085,
			0x5, 0x00A,	0x8, 0x096,	0x8, 0x09C,	0x9, 0x1C3,	0x9, 0x19C,	0x9, 0x08F,	0x9, 0x18F,	0x9, 0x091,
			0x9, 0x087,	0x9, 0x0C6,	0x9, 0x177,	0x9, 0x089,	0x9, 0x0D6,	0x9, 0x08C,	0x9, 0x1EE,	0x9, 0x1EB,
			0x9, 0x084,	0x9, 0x164,	0x9, 0x175,	0x9, 0x1CD,	0x8, 0x05E,	0x9, 0x088,	0x9, 0x12B,	0x9, 0x172,
			0x9, 0x10A,	0x9, 0x08D,	0x9, 0x13A,	0x9, 0x11C,	0xA, 0x1E1,	0xA, 0x1E0,	0x9, 0x187,	0xA, 0x1DC,
			0xA, 0x1DF,	0x7, 0x074,	0x9, 0x19F,	0x8, 0x08D,	0x8, 0x0E4,	0x7, 0x079,	0x9, 0x0EA,	0x9, 0x0E1,
			0x8, 0x040,	0x7, 0x041,	0x9, 0x10B,	0x9, 0x0B0,	0x8, 0x06A,	0x8, 0x0C1,	0x7, 0x071,	0x7, 0x078,
			0x8, 0x0B1,	0x9, 0x14C,	0x7, 0x043,	0x8, 0x076,	0x7, 0x066,	0x7, 0x04D,	0x9, 0x08A,	0x6, 0x02F,
			0x8, 0x0C9,	0x9, 0x0CE,	0x9, 0x149,	0x9, 0x160,	0xA, 0x1BA,	0xA, 0x19E,	0xA, 0x39F,	0x9, 0x0E5,
			0x9, 0x194,	0x9, 0x184,	0x9, 0x126,	0x7, 0x030,	0x8, 0x06C,	0x9, 0x121,	0x9, 0x1E8,	0xA, 0x1C1,
			0xA, 0x11D,	0xA, 0x163,	0xA, 0x385,	0xA, 0x3DB,	0xA, 0x17D,	0xA, 0x106,	0xA, 0x397,	0xA, 0x24E,
			0x7, 0x02E,	0x8, 0x098,	0xA, 0x33C,	0xA, 0x32E,	0xA, 0x1E9,	0x9, 0x0BF,	0xA, 0x3DF,	0xA, 0x1DD,
			0xA, 0x32D,	0xA, 0x2ED,	0xA, 0x30B,	0xA, 0x107,	0xA, 0x2E8,	0xA, 0x3DE,	0xA, 0x125,	0xA, 0x1E8,
			0x9, 0x0E9,	0xA, 0x1CD,	0xA, 0x1B5,	0x9, 0x165,	0xA, 0x232,	0xA, 0x2E1,	0xB, 0x3AE,	0xB, 0x3C6,
			0xB, 0x3E2,	0xA, 0x205,	0xA, 0x29A,	0xA, 0x248,	0xA, 0x2CD,	0xA, 0x23B,	0xB, 0x3C5,	0xA, 0x251,
			0xA, 0x2E9,	0xA, 0x252,	0x9, 0x1EA,	0xB, 0x3A0,	0xB, 0x391,	0xA, 0x23C,	0xB, 0x392,	0xB, 0x3D5,
			0xA, 0x233,	0xA, 0x2CC,	0xB, 0x390,	0xA, 0x1BB,	0xB, 0x3A1,	0xB, 0x3C4,	0xA, 0x211,	0xA, 0x203,
			0x9, 0x12A,	0xA, 0x231,	0xB, 0x3E0,	0xA, 0x29B,	0xB, 0x3D7,	0xA, 0x202,	0xB, 0x3AD,	0xA, 0x213,
			0xA, 0x253,	0xA, 0x32C,	0xA, 0x23D,	0xA, 0x23F,	0xA, 0x32F,	0xA, 0x11C,	0xA, 0x384,	0xA, 0x31C,
			0xA, 0x17C,	0xA, 0x30A,	0xA, 0x2E0,	0xA, 0x276,	0xA, 0x250,	0xB, 0x3E3,	0xA, 0x396,	0xA, 0x18F,
			0xA, 0x204,	0xA, 0x206,	0xA, 0x230,	0xA, 0x265,	0xA, 0x212,	0xA, 0x23E,	0xB, 0x3AC,	0xB, 0x393,
			0xB, 0x3E1,	0xA, 0x1DE,	0xB, 0x3D6,	0xA, 0x31D,	0xB, 0x3E5,	0xB, 0x3E4,	0xA, 0x207,	0xB, 0x3C7,
			0xA, 0x277,	0xB, 0x3D4,	0x8, 0x0C0,	0xA, 0x162,	0xA, 0x3DA,	0xA, 0x124,	0xA, 0x1B4,	0xA, 0x264,
			0xA, 0x33D,	0xA, 0x1D1,	0xA, 0x1AF,	0xA, 0x39E,	0xA, 0x24F,	0xB, 0x373,	0xA, 0x249,	0xB, 0x372,
			0x9, 0x167,	0xA, 0x210,	0xA, 0x23A,	0xA, 0x1B8,	0xB, 0x3AF,	0xA, 0x18E,	0xA, 0x2EC,	0x7, 0x062,
			0x4, 0x00D
		};

        private const int CountIndex = 0;
        private const int ValueIndex = 1;

        // UO packets may not exceed 64kb in length
        private const int BufferSize = 0x10000;

        // Optimal compression ratio is 2 / 8;  worst compression ratio is 11 / 8
        private const int MinimalCodeLength = 2;
        private const int MaximalCodeLength = 11;

        // Fixed overhead, in bits, per compression call
        private const int TerminalCodeLength = 4;

        // If our input exceeds this length, we cannot possibly compress it within the buffer
        private const int DefiniteOverflow = ((BufferSize * 8) - TerminalCodeLength) / MinimalCodeLength;

        // If our input exceeds this length, we may potentially overflow the buffer
        private const int PossibleOverflow = ((BufferSize * 8) - TerminalCodeLength) / MaximalCodeLength;

        private static object _syncRoot = new object();

        private static byte[] _outputBuffer = new byte[BufferSize];

        [Obsolete("Use Compress( byte[], int, int, ref int ) instead.", false)]
        public static void Compress(byte[] input, int length, out byte[] output, out int outputLength)
        {
            outputLength = 0;
            output = Compress(input, 0, length, ref outputLength);
        }

        public unsafe static byte[] Compress(byte[] input, int offset, int count, ref int length)
        {
            if (input == null)
            {
                throw new ArgumentNullException("input");
            }
            else if (offset < 0 || offset >= input.Length)
            {
                throw new ArgumentOutOfRangeException("offset");
            }
            else if (count < 0 || count > input.Length)
            {
                throw new ArgumentOutOfRangeException("count");
            }
            else if ((input.Length - offset) < count)
            {
                throw new ArgumentException();
            }

            length = 0;

            if (count > DefiniteOverflow)
            {
                return null;
            }

            lock (_syncRoot)
            {
                int bitCount = 0;
                int bitValue = 0;

                fixed (int* pTable = _huffmanTable)
                {
                    int* pEntry;

                    fixed (byte* pInputBuffer = input)
                    {
                        byte* pInput = pInputBuffer + offset, pInputEnd = pInput + count;

                        fixed (byte* pOutputBuffer = _outputBuffer)
                        {
                            byte* pOutput = pOutputBuffer, pOutputEnd = pOutput + BufferSize;

                            while (pInput < pInputEnd)
                            {
                                pEntry = &pTable[*pInput++ << 1];

                                bitCount += pEntry[CountIndex];

                                bitValue <<= pEntry[CountIndex];
                                bitValue |= pEntry[ValueIndex];

                                while (bitCount >= 8)
                                {
                                    bitCount -= 8;

                                    if (pOutput < pOutputEnd)
                                    {
                                        *pOutput++ = (byte)(bitValue >> bitCount);
                                    }
                                    else
                                    {
                                        return null;
                                    }
                                }
                            }

                            // terminal code
                            pEntry = &pTable[0x200];

                            bitCount += pEntry[CountIndex];

                            bitValue <<= pEntry[CountIndex];
                            bitValue |= pEntry[ValueIndex];

                            // align on byte boundary
                            if ((bitCount & 7) != 0)
                            {
                                bitValue <<= (8 - (bitCount & 7));
                                bitCount += (8 - (bitCount & 7));
                            }

                            while (bitCount >= 8)
                            {
                                bitCount -= 8;

                                if (pOutput < pOutputEnd)
                                {
                                    *pOutput++ = (byte)(bitValue >> bitCount);
                                }
                                else
                                {
                                    return null;
                                }
                            }

                            length = (int)(pOutput - pOutputBuffer);
                            return _outputBuffer;
                        }
                    }
                }
            }
        }

        public static readonly ICompressor Compressor;

        static Compression()
        {
            if (Core.Unix)
            {
                if (Core.Is64Bit)
                {
                    Compressor = new CompressorUnix64();
                }
                else
                {
                    Compressor = new CompressorUnix32();
                }
            }
            else if (Core.Is64Bit)
            {
                Compressor = new Compressor64();
            }
            else
            {
                Compressor = new Compressor32();
            }
        }

        public static ZLibError Pack(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return Compressor.Compress(dest, ref destLength, source, sourceLength);
        }

        public static ZLibError Pack(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            return Compressor.Compress(dest, ref destLength, source, sourceLength, quality);
        }

        public static ZLibError Unpack(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return Compressor.Decompress(dest, ref destLength, source, sourceLength);
        }
    }

    public interface ICompressor
    {
        string Version
        {
            get;
        }

        ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength);
        ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality);

        ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength);
    }

    public sealed class Compressor32 : ICompressor
    {
        [DllImport("zlib32")]
        private static extern string zlibVersion();

        [DllImport("zlib32")]
        private static extern ZLibError compress(byte[] dest, ref int destLength, byte[] source, int sourceLength);

        [DllImport("zlib32")]
        private static extern ZLibError compress2(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality);

        [DllImport("zlib32")]
        private static extern ZLibError uncompress(byte[] dest, ref int destLen, byte[] source, int sourceLen);

        public Compressor32()
        {
        }

        public string Version
        {
            get
            {
                return zlibVersion();
            }
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return compress(dest, ref destLength, source, sourceLength);
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            return compress2(dest, ref destLength, source, sourceLength, quality);
        }

        public ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return uncompress(dest, ref destLength, source, sourceLength);
        }
    }

    public sealed class Compressor64 : ICompressor
    {
        [DllImport("zlib64")]
        private static extern string zlibVersion();

        [DllImport("zlib64")]
        private static extern ZLibError compress(byte[] dest, ref int destLength, byte[] source, int sourceLength);

        [DllImport("zlib64")]
        private static extern ZLibError compress2(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality);

        [DllImport("zlib64")]
        private static extern ZLibError uncompress(byte[] dest, ref int destLen, byte[] source, int sourceLen);

        public Compressor64()
        {
        }

        public string Version
        {
            get
            {
                return zlibVersion();
            }
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return compress(dest, ref destLength, source, sourceLength);
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            return compress2(dest, ref destLength, source, sourceLength, quality);
        }

        public ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return uncompress(dest, ref destLength, source, sourceLength);
        }
    }

    public sealed class CompressorUnix32 : ICompressor
    {
        [DllImport("libz")]
        private static extern string zlibVersion();

        [DllImport("libz")]
        private static extern ZLibError compress(byte[] dest, ref int destLength, byte[] source, int sourceLength);

        [DllImport("libz")]
        private static extern ZLibError compress2(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality);

        [DllImport("libz")]
        private static extern ZLibError uncompress(byte[] dest, ref int destLen, byte[] source, int sourceLen);

        public CompressorUnix32()
        {
        }

        public string Version
        {
            get
            {
                return zlibVersion();
            }
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return compress(dest, ref destLength, source, sourceLength);
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            return compress2(dest, ref destLength, source, sourceLength, quality);
        }

        public ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            return uncompress(dest, ref destLength, source, sourceLength);
        }
    }

    public sealed class CompressorUnix64 : ICompressor
    {
        [DllImport("libz")]
        private static extern string zlibVersion();

        [DllImport("libz")]
        private static extern ZLibError compress(byte[] dest, ref ulong destLength, byte[] source, int sourceLength);

        [DllImport("libz")]
        private static extern ZLibError compress2(byte[] dest, ref ulong destLength, byte[] source, int sourceLength, ZLibQuality quality);

        [DllImport("libz")]
        private static extern ZLibError uncompress(byte[] dest, ref ulong destLen, byte[] source, int sourceLen);

        public CompressorUnix64()
        {
        }

        public string Version
        {
            get
            {
                return zlibVersion();
            }
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            ulong destLengthLong = (ulong)destLength;
            ZLibError z = compress(dest, ref destLengthLong, source, sourceLength);
            destLength = (int)destLengthLong;
            return z;
        }

        public ZLibError Compress(byte[] dest, ref int destLength, byte[] source, int sourceLength, ZLibQuality quality)
        {
            ulong destLengthLong = (ulong)destLength;
            ZLibError z = compress2(dest, ref destLengthLong, source, sourceLength, quality);
            destLength = (int)destLengthLong;
            return z;
        }

        public ZLibError Decompress(byte[] dest, ref int destLength, byte[] source, int sourceLength)
        {
            ulong destLengthLong = (ulong)destLength;
            ZLibError z = uncompress(dest, ref destLengthLong, source, sourceLength);
            destLength = (int)destLengthLong;
            return z;
        }
    }

    public enum ZLibError : int
    {
        VersionError = -6,
        BufferError = -5,
        MemoryError = -4,
        DataError = -3,
        StreamError = -2,
        FileError = -1,

        Okay = 0,

        StreamEnd = 1,
        NeedDictionary = 2
    }

    public enum ZLibQuality : int
    {
        Default = -1,

        None = 0,

        Speed = 1,
        Size = 9
    }
}