using System.IO;

namespace XTSSharp;

public class XtsSectorStream : SectorStream
{
    public const int DEFAULT_SECTOR_SIZE = 512;
    private readonly byte[] _tempBuffer;
    private readonly Xts _xts;
    private XtsCryptoTransform _decryptor;
    private XtsCryptoTransform _encryptor;

    public XtsSectorStream(Stream baseStream, Xts xts)
        : this(baseStream, xts, 512)
    {
    }

    public XtsSectorStream(Stream baseStream, Xts xts, int sectorSize)
        : this(baseStream, xts, sectorSize, 0L)
    {
    }

    public XtsSectorStream(Stream baseStream, Xts xts, int sectorSize, long offset)
        : base(baseStream, sectorSize, offset)
    {
        _xts = xts;
        _tempBuffer = new byte[sectorSize];
    }

    protected override void Dispose(bool disposing)
    {
        base.Dispose(disposing);
        if (_encryptor != null)
        {
            _encryptor.Dispose();
        }
        if (_decryptor != null)
        {
            _decryptor.Dispose();
        }
    }

    public override void Write(byte[] buffer, int offset, int count)
    {
        ValidateSize(count);
        if (count != 0)
        {
            ulong currentSector = base.CurrentSector;
            if (_encryptor == null)
            {
                _encryptor = _xts.CreateEncryptor();
            }
            int count2 = _encryptor.TransformBlock(buffer, offset, count, _tempBuffer, 0, currentSector);
            base.Write(_tempBuffer, 0, count2);
        }
    }

    public override int Read(byte[] buffer, int offset, int count)
    {
        ValidateSize(count);
        ulong currentSector = base.CurrentSector;
        int num = base.Read(_tempBuffer, 0, count);
        if (num == 0)
        {
            return 0;
        }
        if (_decryptor == null)
        {
            _decryptor = _xts.CreateDecryptor();
        }
        return _decryptor.TransformBlock(_tempBuffer, 0, num, buffer, offset, currentSector);
    }
}