using System.Text;
using Bmp.Core.Lite.Playback.Outputs.NAudioASIO.Originals;
using NAudio.Wave;

namespace Bmp.Core.Lite.Playback.Inputs;

public class DsfAudioStream : DsdAudioStream, IHaveDecoderInfo, IHaveAsioSampleFormat
{
    public const string SIGNATURE_DSD = "DSD ";
    private const string SIGNATURE_FMT = "fmt ";
    private const string SIGNATURE_DATA = "data";

    string IHaveDecoderInfo.DecoderName => "DSF";
    string? IHaveDecoderInfo.FileFormat => $"V{_formatVersion}";
    public AsioSampleType? AsioSampleFormat => AsioSampleType.DSDInt8LSB1;

    private readonly Stream _underlyingStream;
    private readonly bool _disposeStream;

    private readonly long _dataChunkBeginOffset;
    private readonly long _dataChunkEndOffset;
    private readonly long _dataSize;
    private readonly long _pointerToMetadataChunk;

    public int ChannelNum { get; }
    public int SampleRate { get; }
    public int ClusterSizePerChannel { get; }
    public int BitPerSample { get; }

    public override WaveFormat WaveFormat { get; }

    private readonly byte[] _clusterBuf;
    private int _clusterBufSize;
    private int _clusterPtrByChannel;
    private readonly int _formatVersion;

    public static bool IsDsfFile(Stream stream)
    {
        if (stream.Length > 4)
        {
            using var binaryReader = new BinaryReader(stream, Encoding.UTF8, true);
            var signatureDSD = Encoding.ASCII.GetString(binaryReader.ReadBytes(4));
            if (signatureDSD == SIGNATURE_DSD) return true;
        }
        return false;
    }

    public DsfAudioStream(string urlOrPath) : this(InputSourceProviderLite.ReadContentAsSeekableStream(urlOrPath), true)
    {
    }

    public DsfAudioStream(Stream underlyingStream, bool disposeStream)
    {
        if (underlyingStream.CanSeek == false) throw new ArgumentException("stream not seekable");
        _underlyingStream = underlyingStream;
        _disposeStream = disposeStream;

        if (_underlyingStream.Length < 4) throw new InvalidDataException("too small as dsf file");

        _underlyingStream.Position = 0;

        using var reader = new BinaryReader(_underlyingStream, Encoding.UTF8, true);
        var dsdSignature = Encoding.ASCII.GetString(reader.ReadBytes(4));
        if (SIGNATURE_DSD != dsdSignature) throw new InvalidDataException("invalid DSD signature");
        var dsdSizeOfThisChunk = reader.ReadInt64();
        if (dsdSizeOfThisChunk != 28) throw new InvalidDataException("invalid dsd chunk size");
        var totalFileSize = reader.ReadInt64();
        if (totalFileSize != _underlyingStream.Length) throw new InvalidDataException("invalid total file size");
        _pointerToMetadataChunk = reader.ReadInt64();

        var fmtSignature = Encoding.ASCII.GetString(reader.ReadBytes(4));
        if (SIGNATURE_FMT != fmtSignature) throw new InvalidDataException("invalid FMT signature");
        var fmtSizeOfThisChunk = reader.ReadInt64();
        if (fmtSizeOfThisChunk != 52) throw new NotSupportedException("not supported fmt chunk size");
        _formatVersion = reader.ReadInt32();
        var formatId = reader.ReadInt32();
        if (formatId != 0) throw new NotSupportedException("only DSD raw supported");

        var channelType = reader.ReadInt32();
        ChannelNum = reader.ReadInt32();
        SampleRate = reader.ReadInt32();
        BitPerSample = reader.ReadInt32();

        var sampleCount = reader.ReadInt64();
        ClusterSizePerChannel = reader.ReadInt32();
        var rsv0000 = reader.ReadInt32();

        var dataSignature = Encoding.ASCII.GetString(reader.ReadBytes(4));
        if (SIGNATURE_DATA != dataSignature) throw new InvalidDataException("invalid data signature");
        var dataSizeOfThisChunk = reader.ReadInt64();

        _dataSize = dataSizeOfThisChunk - 12;
        _dataChunkBeginOffset = _underlyingStream.Position;
        _dataChunkEndOffset = _dataChunkBeginOffset + _dataSize;

        var align = ClusterSizePerChannel * ChannelNum;
        WaveFormat = WaveFormat.CreateCustomFormat(WaveFormatEncoding.Unknown, SampleRate, ChannelNum, SampleRate * channelType / 8, align, 1);

        _clusterBuf = new byte[align];
    }

    private bool ReadCluster()
    {
        //  block[ChannelNum]
        //  blockPtr
        //  blockSize = Chunk/ChannelNum

        var readCount = 0;
        do
        {
            var safeCount = Math.Min(_clusterBuf.Length - readCount, _dataChunkEndOffset - _underlyingStream.Position);
            if (safeCount <= 0) break;

            var read = _underlyingStream.Read(_clusterBuf, readCount, (int)safeCount);
            if (read == 0) break;

            readCount += read;
        } while (readCount < _clusterBuf.Length);

        _clusterBufSize = readCount;
        _clusterPtrByChannel = 0;

        return readCount != 0;
    }

    public override int Read(byte[] buffer, int offset, int countRequired)
    {
        if (countRequired == 0) return 0;

        if (countRequired < ChannelNum) throw new ArgumentOutOfRangeException(nameof(countRequired));
        var mod = countRequired % ChannelNum;
        var count = countRequired;
        if (mod != 0) count -= mod;

        //对齐 BlockSizePerChannel 声道交替字节 (FAKE BIT PER SAMPLE 8bit) or ( 16 SHORT/ 32 INT/ 64 LONG)

        //Source L[BlockSizePerChannel] R[BlockSizePerChannel] L[BlockSizePerChannel] R[BlockSizePerChannel] -> Transfer LR LR LR LR

        if (_clusterBufSize == 0)
        {
            if (ReadCluster() == false) return 0;
        }

        var bytes = count / ChannelNum;
        var dstPtr = 0;

        //TODO: DsfAudioStream optimization Unsafe moving ptr

        for (var s = 0; s < bytes; s++)
        {
            for (var ch = 0; ch < ChannelNum; ch++)
            {
                var srcPtr = ch * ClusterSizePerChannel + _clusterPtrByChannel;

                buffer[dstPtr] = _clusterBuf[srcPtr];

                ++dstPtr;
            }

            _clusterPtrByChannel++;

            if (_clusterPtrByChannel * ChannelNum == _clusterBufSize)
            {
                if (!ReadCluster()) break;
            }
        }

        return dstPtr;
    }

    public override long Length => _dataSize;

    public override long Position
    {
        get => _underlyingStream.Position - _dataChunkBeginOffset;
        set => _underlyingStream.Position = _dataChunkBeginOffset + value - value % (ClusterSizePerChannel * ChannelNum);
    }

    protected override void Dispose(bool disposing)
    {
        base.Dispose(disposing);
        if (_disposeStream) _underlyingStream.Dispose();
    }
}