using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using SharpCompress.Common.Rar;
using SharpCompress.IO;
using size_t = System.UInt32;

namespace SharpCompress.Common.Rar.Headers;

internal partial class FileHeader : RarHeader
{
    private byte[]? _hash;

    public static FileHeader Create(
        RarHeader header,
        RarCrcBinaryReader reader,
        HeaderType headerType
    ) => CreateChild<FileHeader>(header, reader, headerType);

    protected override void ReadFinish(MarkingBinaryReader reader)
    {
        if (IsRar5)
        {
            ReadFromReaderV5(reader);
        }
        else
        {
            ReadFromReaderV4(reader);
        }
    }

    private void ReadFromReaderV5(MarkingBinaryReader reader)
    {
        Flags = reader.ReadRarVIntUInt16();

        var lvalue = checked((long)reader.ReadRarVInt());

        // long.MaxValue causes the unpack code to finish when the input stream is exhausted
        UncompressedSize = HasFlag(FileFlagsV5.UNPACKED_SIZE_UNKNOWN) ? long.MaxValue : lvalue;

        FileAttributes = reader.ReadRarVIntUInt32();

        if (HasFlag(FileFlagsV5.HAS_MOD_TIME))
        {
            FileLastModifiedTime = Utility.UnixTimeToDateTime(reader.ReadUInt32());
        }

        if (HasFlag(FileFlagsV5.HAS_CRC32))
        {
            FileCrc = reader.ReadBytes(4);
        }

        var compressionInfo = reader.ReadRarVIntUInt16();

        // Lower 6 bits (0x003f mask) contain the version of compression algorithm, resulting in possible 0 - 63 values. Current version is 0.
        // "+ 50" to not mix with old RAR format algorithms. For example,
        // we may need to use the compression algorithm 15 in the future,
        // but it was already used in RAR 1.5 and Unpack needs to distinguish
        // them.
        CompressionAlgorithm = (byte)((compressionInfo & 0x3f) + 50);

        // 7th bit (0x0040) defines the solid flag. If it is set, RAR continues to use the compression dictionary left after processing preceding files.
        // It can be set only for file headers and is never set for service headers.
        IsSolid = (compressionInfo & 0x40) == 0x40;

        // Bits 8 - 10 (0x0380 mask) define the compression method. Currently only values 0 - 5 are used. 0 means no compression.
        CompressionMethod = (byte)((compressionInfo >> 7) & 0x7);

        // Bits 11 - 14 (0x3c00) define the minimum size of dictionary size required to extract data. Value 0 means 128 KB, 1 - 256 KB, ..., 14 - 2048 MB, 15 - 4096 MB.
        WindowSize = IsDirectory ? 0 : ((size_t)0x20000) << ((compressionInfo >> 10) & 0xf);

        _ = reader.ReadRarVIntByte();

        var nameSize = reader.ReadRarVIntUInt16();

        var b = reader.ReadBytes(nameSize);
        FileName = ConvertPathV5(Encoding.UTF8.GetString(b, 0, b.Length));

        // extra size seems to be redudant since we know the total header size
        if (ExtraSize != RemainingHeaderBytes(reader))
        {
            throw new InvalidFormatException("rar5 header size / extra size inconsistency");
        }

        const ushort FHEXTRA_CRYPT = 0x01;
        const ushort FHEXTRA_HASH = 0x02;
        const ushort FHEXTRA_HTIME = 0x03;
        // const ushort FHEXTRA_VERSION = 0x04;
        const ushort FHEXTRA_REDIR = 0x05;
        // const ushort FHEXTRA_UOWNER = 0x06;
        // const ushort FHEXTRA_SUBDATA = 0x07;

        while (RemainingHeaderBytes(reader) > 0)
        {
            var size = reader.ReadRarVIntUInt16();
            var n = RemainingHeaderBytes(reader);
            var type = reader.ReadRarVIntUInt16();
            switch (type)
            {
                case FHEXTRA_CRYPT: // file encryption
                    {
                        Rar5CryptoInfo = Rar5CryptoInfo.Create(reader, true);

                        if (Rar5CryptoInfo.PswCheck.All(singleByte => singleByte == 0))
                        {
                            Rar5CryptoInfo = null;
                        }
                    }
                    break;
                case FHEXTRA_HASH:
                    {
                        const uint FHEXTRA_HASH_BLAKE2 = 0x0;
                        const int BLAKE2_DIGEST_SIZE = 0x20;
                        if ((uint)reader.ReadRarVInt() == FHEXTRA_HASH_BLAKE2)
                        {
                            _hash = reader.ReadBytes(BLAKE2_DIGEST_SIZE);
                        }
                    }
                    break;
                case FHEXTRA_HTIME: // file time
                    {
                        var flags = reader.ReadRarVIntUInt16();
                        var isWindowsTime = (flags & 1) == 0;
                        if ((flags & 0x2) == 0x2)
                        {
                            FileLastModifiedTime = ReadExtendedTimeV5(reader, isWindowsTime);
                        }
                        if ((flags & 0x4) == 0x4)
                        {
                            FileCreatedTime = ReadExtendedTimeV5(reader, isWindowsTime);
                        }
                        if ((flags & 0x8) == 0x8)
                        {
                            FileLastAccessedTime = ReadExtendedTimeV5(reader, isWindowsTime);
                        }
                    }
                    break;
                case FHEXTRA_REDIR: // file system redirection
                    {
                        RedirType = reader.ReadRarVIntByte();
                        RedirFlags = reader.ReadRarVIntByte();
                        var nn = reader.ReadRarVIntUInt16();
                        var bb = reader.ReadBytes(nn);
                        RedirTargetName = ConvertPathV5(Encoding.UTF8.GetString(bb, 0, bb.Length));
                    }
                    break;
                default:
                    break;
            }
            // drain any trailing bytes of extra record
            var did = n - RemainingHeaderBytes(reader);
            var drain = size - did;
            if (drain > 0)
            {
                reader.ReadBytes(drain);
            }
        }

        if (AdditionalDataSize != 0)
        {
            CompressedSize = AdditionalDataSize;
        }
    }

    private static DateTime ReadExtendedTimeV5(MarkingBinaryReader reader, bool isWindowsTime)
    {
        if (isWindowsTime)
        {
            return DateTime.FromFileTime(reader.ReadInt64());
        }
        else
        {
            return Utility.UnixTimeToDateTime(reader.ReadUInt32());
        }
    }

    private static string ConvertPathV5(string path)
    {
        if (Path.DirectorySeparatorChar == '\\')
        {
            // replace embedded \\ with valid filename char
            return path.Replace('\\', '-').Replace('/', '\\');
        }
        return path;
    }

    private void ReadFromReaderV4(MarkingBinaryReader reader)
    {
        Flags = HeaderFlags;
        IsSolid = HasFlag(FileFlagsV4.SOLID);
        WindowSize = IsDirectory
            ? 0U
            : ((size_t)0x10000) << ((Flags & FileFlagsV4.WINDOW_MASK) >> 5);

        var lowUncompressedSize = reader.ReadUInt32();

        _ = reader.ReadByte();

        FileCrc = reader.ReadBytes(4);

        FileLastModifiedTime = Utility.DosDateToDateTime(reader.ReadUInt32());

        CompressionAlgorithm = reader.ReadByte();
        CompressionMethod = (byte)(reader.ReadByte() - 0x30);

        var nameSize = reader.ReadInt16();

        FileAttributes = reader.ReadUInt32();

        uint highCompressedSize = 0;
        uint highUncompressedkSize = 0;
        if (HasFlag(FileFlagsV4.LARGE))
        {
            highCompressedSize = reader.ReadUInt32();
            highUncompressedkSize = reader.ReadUInt32();
        }
        else
        {
            if (lowUncompressedSize == 0xffffffff)
            {
                lowUncompressedSize = 0xffffffff;
                highUncompressedkSize = int.MaxValue;
            }
        }
        CompressedSize = UInt32To64(highCompressedSize, checked((uint)AdditionalDataSize));
        UncompressedSize = UInt32To64(highUncompressedkSize, lowUncompressedSize);

        nameSize = nameSize > 4 * 1024 ? (short)(4 * 1024) : nameSize;

        var fileNameBytes = reader.ReadBytes(nameSize);

        const int newLhdSize = 32;

        switch (HeaderCode)
        {
            case HeaderCodeV.RAR4_FILE_HEADER:
                {
                    if (HasFlag(FileFlagsV4.UNICODE))
                    {
                        var length = 0;
                        while (length < fileNameBytes.Length && fileNameBytes[length] != 0)
                        {
                            length++;
                        }
                        if (length != nameSize)
                        {
                            length++;
                            FileName = FileNameDecoder.Decode(fileNameBytes, length);
                        }
                        else
                        {
                            FileName = ArchiveEncoding.Decode(fileNameBytes);
                        }
                    }
                    else
                    {
                        FileName = ArchiveEncoding.Decode(fileNameBytes);
                    }
                    FileName = ConvertPathV4(FileName);
                }
                break;
            case HeaderCodeV.RAR4_NEW_SUB_HEADER:
                {
                    var datasize = HeaderSize - newLhdSize - nameSize;
                    if (HasFlag(FileFlagsV4.SALT))
                    {
                        datasize -= EncryptionConstV5.SIZE_SALT30;
                    }
                    if (datasize > 0)
                    {
                        SubData = reader.ReadBytes(datasize);
                    }

                    if (NewSubHeaderType.SUBHEAD_TYPE_RR.Equals(fileNameBytes))
                    {
                        if (SubData is null)
                        {
                            throw new InvalidFormatException();
                        }
                        RecoverySectors =
                            SubData[8]
                            + (SubData[9] << 8)
                            + (SubData[10] << 16)
                            + (SubData[11] << 24);
                    }
                }
                break;
        }

        if (HasFlag(FileFlagsV4.SALT))
        {
            R4Salt = reader.ReadBytes(EncryptionConstV5.SIZE_SALT30);
        }
        if (HasFlag(FileFlagsV4.EXT_TIME))
        {
            if (RemainingHeaderBytes(reader) >= 2)
            {
                var extendedFlags = reader.ReadUInt16();
                if (FileLastModifiedTime is not null)
                {
                    FileLastModifiedTime = ProcessExtendedTimeV4(
                        extendedFlags,
                        FileLastModifiedTime,
                        reader,
                        0
                    );
                }

                FileCreatedTime = ProcessExtendedTimeV4(extendedFlags, null, reader, 1);
                FileLastAccessedTime = ProcessExtendedTimeV4(extendedFlags, null, reader, 2);
                FileArchivedTime = ProcessExtendedTimeV4(extendedFlags, null, reader, 3);
            }
        }
    }

    private static long UInt32To64(uint x, uint y)
    {
        long l = x;
        l <<= 32;
        return l + y;
    }

    private static DateTime? ProcessExtendedTimeV4(
        ushort extendedFlags,
        DateTime? time,
        MarkingBinaryReader reader,
        int i
    )
    {
        var rmode = (uint)extendedFlags >> ((3 - i) * 4);
        if ((rmode & 8) == 0)
        {
            return null;
        }
        if (i != 0)
        {
            var dosTime = reader.ReadUInt32();
            time = Utility.DosDateToDateTime(dosTime);
        }
        if ((rmode & 4) == 0 && time is not null)
        {
            time = time.Value.AddSeconds(1);
        }
        uint nanosecondHundreds = 0;
        var count = (int)rmode & 3;
        for (var j = 0; j < count; j++)
        {
            var b = reader.ReadByte();
            nanosecondHundreds |= (((uint)b) << ((j + 3 - count) * 8));
        }

        //10^-7 to 10^-3
        if (time is not null)
        {
            return time.Value.AddMilliseconds(nanosecondHundreds * Math.Pow(10, -4));
        }
        return null;
    }

    private static string ConvertPathV4(string path)
    {
        if (Path.DirectorySeparatorChar == '/')
        {
            return path.Replace('\\', '/');
        }
        else if (Path.DirectorySeparatorChar == '\\')
        {
            return path.Replace('/', '\\');
        }
        return path;
    }

    public override string ToString() => FileName ?? "FileHeader";

    private ushort Flags { get; set; }

    private bool HasFlag(ushort flag) => (Flags & flag) == flag;

    internal byte[]? FileCrc
    {
        get => _hash;
        private set => _hash = value;
    }

    // 0 - storing
    // 1 - fastest compression
    // 2 - fast compression
    // 3 - normal compression
    // 4 - good compression
    // 5 - best compression
    internal byte CompressionMethod { get; private set; }
    internal bool IsStored => CompressionMethod == 0;

    // eg (see DoUnpack())
    //case 15: // rar 1.5 compression
    //case 20: // rar 2.x compression
    //case 26: // files larger than 2GB
    //case 29: // rar 3.x compression
    //case 50: // RAR 5.0 compression algorithm.
    internal byte CompressionAlgorithm { get; private set; }

    public bool IsSolid { get; private set; }

    public byte RedirType { get; private set; }
    public bool IsRedir => RedirType != 0;
    public byte RedirFlags { get; private set; }
    public bool IsRedirDirectory => (RedirFlags & RedirFlagV5.DIRECTORY) != 0;
    public string? RedirTargetName { get; private set; }

    // unused for UnpackV1 implementation (limitation)
    internal size_t WindowSize { get; private set; }

    internal byte[]? R4Salt { get; private set; }
    internal Rar5CryptoInfo? Rar5CryptoInfo { get; private set; }
    internal uint FileAttributes { get; private set; }
    internal long CompressedSize { get; private set; }
    internal long UncompressedSize { get; private set; }
    internal string? FileName { get; private set; }
    internal byte[]? SubData { get; private set; }
    internal int RecoverySectors { get; private set; }
    internal long DataStartPosition { get; set; }
    public Stream? PackedStream { get; set; }

    public bool IsSplitBefore =>
        IsRar5 ? HasHeaderFlag(HeaderFlagsV5.SPLIT_BEFORE) : HasFlag(FileFlagsV4.SPLIT_BEFORE);
    public bool IsSplitAfter =>
        IsRar5 ? HasHeaderFlag(HeaderFlagsV5.SPLIT_AFTER) : HasFlag(FileFlagsV4.SPLIT_AFTER);

    public bool IsDirectory => HasFlag(IsRar5 ? FileFlagsV5.DIRECTORY : FileFlagsV4.DIRECTORY);

    public bool IsEncrypted => IsRar5 ? Rar5CryptoInfo != null : HasFlag(FileFlagsV4.PASSWORD);

    internal DateTime? FileLastModifiedTime { get; private set; }

    internal DateTime? FileCreatedTime { get; private set; }

    internal DateTime? FileLastAccessedTime { get; private set; }

    internal DateTime? FileArchivedTime { get; private set; }
}
