using System.Collections.Generic;
using System.IO;
using Lz4;
using SevenZip.Compression.LZMA;

namespace Unity_Studio
{
    public class BundleFile
    {
        public int format;
        public string versionPlayer;
        public string versionEngine;
        public List<MemoryAssetsFile> MemoryAssetsFileList = new List<MemoryAssetsFile>();

        public class MemoryAssetsFile
        {
            public string fileName;
            public MemoryStream memStream;
        }

        public BundleFile(string fileName)
        {
            if (Path.GetExtension(fileName) == ".lz4")
            {
                byte[] filebuffer;

                using (BinaryReader lz4Stream = new BinaryReader(File.OpenRead(fileName)))
                {
                    int version = lz4Stream.ReadInt32();
                    int uncompressedSize = lz4Stream.ReadInt32();
                    int compressedSize = lz4Stream.ReadInt32();
                    int something = lz4Stream.ReadInt32(); //1

                    var lz4buffer = lz4Stream.ReadBytes(compressedSize);
                    using (var inputStream = new MemoryStream(lz4buffer))
                    {
                        var decoder = new Lz4DecoderStream(inputStream);
                        filebuffer = new byte[uncompressedSize];
                        decoder.Read(filebuffer, 0, uncompressedSize);
                        decoder.Dispose();
                    }
                }
                using (var b_Stream = new EndianBinaryReader(new MemoryStream(filebuffer)))
                {
                    readBundle(b_Stream);
                }
            }
            else
            {
                using (var b_Stream = new EndianBinaryReader(File.OpenRead(fileName)))
                {
                    readBundle(b_Stream);
                }
            }
        }

        private void readBundle(EndianBinaryReader b_Stream)
        {
            var signature = b_Stream.ReadStringToNull();
            switch (signature)
            {
                case "UnityWeb":
                case "UnityRaw":
                case "\xFA\xFA\xFA\xFA\xFA\xFA\xFA\xFA":
                    {
                        format = b_Stream.ReadInt32();
                        versionPlayer = b_Stream.ReadStringToNull();
                        versionEngine = b_Stream.ReadStringToNull();
                        if (format < 6)
                        {
                            int bundleSize = b_Stream.ReadInt32();
                        }
                        else if (format == 6)
                        {
                            ReadFormat6(b_Stream, true);
                            return;
                        }
                        short dummy2 = b_Stream.ReadInt16();
                        int offset = b_Stream.ReadInt16();
                        int dummy3 = b_Stream.ReadInt32();
                        int lzmaChunks = b_Stream.ReadInt32();

                        int lzmaSize = 0;
                        long streamSize = 0;

                        for (int i = 0; i < lzmaChunks; i++)
                        {
                            lzmaSize = b_Stream.ReadInt32();
                            streamSize = b_Stream.ReadInt32();
                        }

                        b_Stream.Position = offset;
                        switch (signature)
                        {
                            case "\xFA\xFA\xFA\xFA\xFA\xFA\xFA\xFA": //.bytes
                            case "UnityWeb":
                                {
                                    var lzmaBuffer = b_Stream.ReadBytes(lzmaSize);
                                    using (var lzmaStream = new EndianBinaryReader(SevenZipHelper.StreamDecompress(new MemoryStream(lzmaBuffer))))
                                    {
                                        getFiles(lzmaStream, 0);
                                    }
                                    break;
                                }
                            case "UnityRaw":
                                {
                                    getFiles(b_Stream, offset);
                                    break;
                                }
                        }
                        break;
                    }
                case "UnityFS":
                    format = b_Stream.ReadInt32();
                    versionPlayer = b_Stream.ReadStringToNull();
                    versionEngine = b_Stream.ReadStringToNull();
                    if (format == 6)
                    {
                        ReadFormat6(b_Stream);
                    }
                    break;
            }
        }

        private void getFiles(EndianBinaryReader f_Stream, int offset)
        {
            int fileCount = f_Stream.ReadInt32();
            for (int i = 0; i < fileCount; i++)
            {
                var memFile = new MemoryAssetsFile();
                memFile.fileName = f_Stream.ReadStringToNull();
                int fileOffset = f_Stream.ReadInt32();
                fileOffset += offset;
                int fileSize = f_Stream.ReadInt32();
                long nextFile = f_Stream.Position;
                f_Stream.Position = fileOffset;
                var buffer = f_Stream.ReadBytes(fileSize);
                memFile.memStream = new MemoryStream(buffer);
                MemoryAssetsFileList.Add(memFile);
                f_Stream.Position = nextFile;
            }
        }

        private void ReadFormat6(EndianBinaryReader b_Stream, bool padding = false)
        {
            var bundleSize = b_Stream.ReadInt64();
            int compressedSize = b_Stream.ReadInt32();
            int uncompressedSize = b_Stream.ReadInt32();
            int flag = b_Stream.ReadInt32();
            if (padding)
                b_Stream.ReadByte();
            byte[] blocksInfoBytes;
            if ((flag & 0x80) != 0)//at end of file
            {
                var position = b_Stream.Position;
                b_Stream.Position = b_Stream.BaseStream.Length - compressedSize;
                blocksInfoBytes = b_Stream.ReadBytes(compressedSize);
                b_Stream.Position = position;
            }
            else
            {
                blocksInfoBytes = b_Stream.ReadBytes(compressedSize);
            }
            MemoryStream blocksInfoStream;
            switch (flag & 0x3F)
            {
                default://None
                    {
                        blocksInfoStream = new MemoryStream(blocksInfoBytes);
                        break;
                    }
                case 1://LZMA
                    {
                        blocksInfoStream = SevenZipHelper.StreamDecompress(new MemoryStream(blocksInfoBytes));
                        break;
                    }
                case 2://LZ4
                case 3://LZ4HC
                    {
                        byte[] uncompressedBytes = new byte[uncompressedSize];
                        using (var mstream = new MemoryStream(blocksInfoBytes))
                        {
                            var decoder = new Lz4DecoderStream(mstream);
                            decoder.Read(uncompressedBytes, 0, uncompressedSize);
                            decoder.Dispose();
                        }
                        blocksInfoStream = new MemoryStream(uncompressedBytes);
                        break;
                    }
                    //case 4:LZHAM?
            }
            using (var blocksInfo = new EndianBinaryReader(blocksInfoStream))
            {
                blocksInfo.Position = 0x10;
                int blockcount = blocksInfo.ReadInt32();
                var assetsDataStream = new MemoryStream();
                for (int i = 0; i < blockcount; i++)
                {
                    uncompressedSize = blocksInfo.ReadInt32();
                    compressedSize = blocksInfo.ReadInt32();
                    flag = blocksInfo.ReadInt16();
                    var compressedBytes = b_Stream.ReadBytes(compressedSize);
                    switch (flag & 0x3F)
                    {
                        default://None
                            {
                                assetsDataStream.Write(compressedBytes, 0, compressedSize);
                                break;
                            }
                        case 1://LZMA
                            {
                                var uncompressedBytes = new byte[uncompressedSize];
                                using (var mstream = new MemoryStream(compressedBytes))
                                {
                                    var decoder = SevenZipHelper.StreamDecompress(mstream, uncompressedSize);
                                    decoder.Read(uncompressedBytes, 0, uncompressedSize);
                                    decoder.Dispose();
                                }
                                assetsDataStream.Write(uncompressedBytes, 0, uncompressedSize);
                                break;
                            }
                        case 2://LZ4
                        case 3://LZ4HC
                            {
                                var uncompressedBytes = new byte[uncompressedSize];
                                using (var mstream = new MemoryStream(compressedBytes))
                                {
                                    var decoder = new Lz4DecoderStream(mstream);
                                    decoder.Read(uncompressedBytes, 0, uncompressedSize);
                                    decoder.Dispose();
                                }
                                assetsDataStream.Write(uncompressedBytes, 0, uncompressedSize);
                                break;
                            }
                            //case 4:LZHAM?
                    }
                }
                using (var assetsData = new EndianBinaryReader(assetsDataStream))
                {
                    var entryinfo_count = blocksInfo.ReadInt32();
                    for (int i = 0; i < entryinfo_count; i++)
                    {
                        var memFile = new MemoryAssetsFile();
                        var entryinfo_offset = blocksInfo.ReadInt64();
                        var entryinfo_size = blocksInfo.ReadInt64();
                        var unknown = blocksInfo.ReadInt32();
                        memFile.fileName = blocksInfo.ReadStringToNull();
                        assetsData.Position = entryinfo_offset;
                        var buffer = assetsData.ReadBytes((int)entryinfo_size);
                        memFile.memStream = new MemoryStream(buffer);
                        MemoryAssetsFileList.Add(memFile);
                    }
                }
            }
        }
    }
}