using System;

namespace ScreenConnect;

public class ZStandardEncoder : ZStandardCoder<Native.libzstd.ZSTD_cParameter>
{
	public int WindowLog { get; }

	public int CompressionLevel { get; }

	public ZStandardEncoder(int compressionLevel, int windowLog)
	{
		WindowLog = windowLog;
		CompressionLevel = compressionLevel;
	}

	protected override (Native.libzstd.ZSTD_cParameter, int)[] GetParameterValues()
	{
		return new(Native.libzstd.ZSTD_cParameter, int)[6]
		{
			(Native.libzstd.ZSTD_cParameter.ZSTD_c_compressionLevel, CompressionLevel),
			(Native.libzstd.ZSTD_cParameter.ZSTD_c_windowLog, WindowLog),
			(Native.libzstd.ZSTD_cParameter.ZSTD_c_enableLongDistanceMatching, 1),
			(Native.libzstd.ZSTD_cParameter.ZSTD_c_strategy, 2),
			(Native.libzstd.ZSTD_cParameter.ZSTD_c_hashLog, Math.Max(WindowLog - 7, 0)),
			(Native.libzstd.ZSTD_cParameter.ZSTD_c_chainLog, Math.Max(WindowLog - 7, 0))
		};
	}

	protected override IntPtr CreateStream()
	{
		return NativeLibrarySingleton<Native.libzstd, Toolkit>.Instance.ZSTD_createCCtx();
	}

	protected override IntPtr InitializeStream(IntPtr stream)
	{
		return IntPtr.Zero;
	}

	protected override IntPtr FreeStream(IntPtr stream)
	{
		return NativeLibrarySingleton<Native.libzstd, Toolkit>.Instance.ZSTD_freeCStream(stream);
	}

	protected override IntPtr SetParameterValue(IntPtr stream, Native.libzstd.ZSTD_cParameter parameter, int value)
	{
		return NativeLibrarySingleton<Native.libzstd, Toolkit>.Instance.ZSTD_CCtx_setParameter(stream, parameter, value);
	}

	protected override IntPtr GetInputSize()
	{
		return NativeLibrarySingleton<Native.libzstd, Toolkit>.Instance.ZSTD_CStreamInSize();
	}

	protected override IntPtr GetOutputSize()
	{
		return NativeLibrarySingleton<Native.libzstd, Toolkit>.Instance.ZSTD_CStreamOutSize();
	}

	protected override IntPtr Process(IntPtr stream, ref Native.libzstd.ZSTD_Buffer input, ref Native.libzstd.ZSTD_Buffer output, CoderFlushType flushType)
	{
		return NativeLibrarySingleton<Native.libzstd, Toolkit>.Instance.ZSTD_compressStream2(stream, ref output, ref input, (flushType == CoderFlushType.Sync) ? Native.libzstd.ZSTD_EndDirective.ZSTD_e_flush : Native.libzstd.ZSTD_EndDirective.ZSTD_e_continue);
	}

	public override IntPtr GetCurrentSize(IntPtr stream)
	{
		return NativeLibrarySingleton<Native.libzstd, Toolkit>.Instance.ZSTD_sizeof_CCtx(stream);
	}
}