/*************************************************************************
 * ModernUO                                                              *
 * Copyright 2019-2023 - ModernUO Development Team                       *
 * Email: hi@modernuo.com                                                *
 * File: TileMatrixPatch.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.IO;

namespace Server;

public class TileMatrixPatch
{
    private StaticTile[] _tileBuffer = new StaticTile[128];

    public static bool PatchLandEnabled { get; private set; }
    public static bool PatchStaticsEnabled { get; private set; }

    public int LandBlocks { get; }
    public int StaticBlocks { get; }

    public TileMatrixPatch(TileMatrix matrix, int index)
    {
        if (PatchLandEnabled)
        {
            var mapDataPath = Core.FindDataFile($"mapdif{index}.mul", false);
            var mapIndexPath = Core.FindDataFile($"mapdifl{index}.mul", false);

            if (mapDataPath != null && mapIndexPath != null)
            {
                LandBlocks = PatchLand(matrix, mapDataPath, mapIndexPath);
            }
        }

        if (PatchStaticsEnabled)
        {
            var staDataPath = Core.FindDataFile($"stadif{index}.mul", false);
            var staIndexPath = Core.FindDataFile($"stadifl{index}.mul", false);
            var staLookupPath = Core.FindDataFile($"stadifi{index}.mul", false);

            if (staDataPath != null && staIndexPath != null && staLookupPath != null)
            {
                StaticBlocks = PatchStatics(matrix, staDataPath, staIndexPath, staLookupPath);
            }
        }
    }

    public static void Configure()
    {
        if (UOClient.ServerClientVersion != null)
        {
            PatchLandEnabled = ServerConfiguration.GetSetting(
                "maps.enableMapDiffPatches",
                UOClient.ServerClientVersion < ClientVersion.Version6000
            );

            // TODO: Should this be enabled for 6.0 through <7.0.9?
            PatchStaticsEnabled = ServerConfiguration.GetSetting(
                "maps.enableStaticsDiffPatches",
                UOClient.ServerClientVersion < ClientVersion.Version7090
            );
        }
    }

    private unsafe int PatchLand(TileMatrix matrix, string dataPath, string indexPath)
    {
        using var fsData = new FileStream(dataPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        using var fsIndex = new FileStream(indexPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        using var indexReader = new BinaryReader(fsIndex);

        var count = (int)(indexReader.BaseStream.Length / 4);

        for (var i = 0; i < count; i++)
        {
            var blockID = indexReader.ReadInt32();
            var x = Math.DivRem(blockID, matrix.BlockHeight, out var y);

            fsData.Seek(4, SeekOrigin.Current);

            var tiles = new LandTile[64];
            fixed (LandTile* pTiles = tiles)
            {
                _ = fsData.Read(new Span<byte>(pTiles, 192));
            }

            matrix.SetLandBlock(x, y, tiles);
        }

        return count;
    }

    private unsafe int PatchStatics(TileMatrix matrix, string dataPath, string indexPath, string lookupPath)
    {
        using var fsData = new FileStream(dataPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        using var fsIndex = new FileStream(indexPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        using var fsLookup = new FileStream(lookupPath, FileMode.Open, FileAccess.Read, FileShare.Read);
        using var indexReader = new BinaryReader(fsIndex);
        using var lookupReader = new BinaryReader(fsLookup);

        var count = (int)(indexReader.BaseStream.Length / 4);

        var lists = new TileList[8][];

        for (var x = 0; x < 8; ++x)
        {
            lists[x] = new TileList[8];

            for (var y = 0; y < 8; ++y)
            {
                lists[x][y] = new TileList();
            }
        }

        for (var i = 0; i < count; ++i)
        {
            var blockID = indexReader.ReadInt32();
            var blockX = blockID / matrix.BlockHeight;
            var blockY = blockID % matrix.BlockHeight;

            var offset = lookupReader.ReadInt32();
            var length = lookupReader.ReadInt32();
            lookupReader.ReadInt32(); // Extra

            if (offset < 0 || length <= 0)
            {
                matrix.SetStaticBlock(blockX, blockY, matrix.EmptyStaticBlock);
                continue;
            }

            fsData.Seek(offset, SeekOrigin.Begin);

            var tileCount = length / 7;

            if (_tileBuffer.Length < tileCount)
            {
                _tileBuffer = new StaticTile[tileCount];
            }

            var staTiles = _tileBuffer;

            fixed (StaticTile* pTiles = staTiles)
            {
                _ = fsData.Read(new Span<byte>(pTiles, length));

                StaticTile* pCur = pTiles, pEnd = pTiles + tileCount;

                while (pCur < pEnd)
                {
                    lists[pCur->m_X & 0x7][pCur->m_Y & 0x7].Add(pCur);
                    pCur += 1;
                }

                var tiles = new StaticTile[8][][];

                for (var x = 0; x < 8; ++x)
                {
                    tiles[x] = new StaticTile[8][];

                    for (var y = 0; y < 8; ++y)
                    {
                        tiles[x][y] = lists[x][y].ToArray();
                    }
                }

                matrix.SetStaticBlock(blockX, blockY, tiles);
            }
        }

        return count;
    }
}