using System;
using System.IO;
using SharpAvi;
using SharpAvi.Codecs;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Formats.Jpeg;
using SixLabors.ImageSharp.PixelFormats;

namespace DispenserUI.ViewModels.Recorder;

public class MJpegImageVideoEncoder : IVideoEncoder
{
    private readonly int _width;
    private readonly int _height;
    private readonly JpegEncoder _jpegEncoder;
    private readonly MemoryStream _buffer;

    /// <summary>
    /// Creates a new instance of <see cref="T:SharpAvi.Codecs.MJpegImageSharpVideoEncoder" />.
    /// </summary>
    /// <param name="width">Frame width.</param>
    /// <param name="height">Frame height.</param>
    /// <param name="quality">
    /// Compression quality in the range [1..100].
    /// Less values mean less size and lower image quality.
    /// </param>
    public MJpegImageVideoEncoder(int width, int height, int quality)
    {
        this._width = width;
        this._height = height;
        _buffer = new MemoryStream(this.MaxEncodedSize);
        _jpegEncoder = new JpegEncoder
        {
            Quality = quality,
        };
    }

    /// <summary>Video codec.</summary>
    public FourCC Codec => CodecIds.MotionJpeg;

    /// <summary>Number of bits per pixel in encoded image.</summary>
    public BitsPerPixel BitsPerPixel => BitsPerPixel.Bpp24;

    /// <summary>Maximum size of encoded frmae.</summary>
    public int MaxEncodedSize => Math.Max(_width * _height * 3, 1024);

    /// <summary>Encodes a frame.</summary>
    public int EncodeFrame(
        byte[] source,
        int srcOffset,
        byte[] destination,
        int destOffset,
        out bool isKeyFrame)
    {
        int num;
        using (MemoryStream destination1 = new MemoryStream(destination))
        {
            destination1.Position = destOffset;
            num = LoadAndEncodeImage(source.AsSpan(srcOffset), destination1);
        }

        isKeyFrame = true;
        return num;
    }

    /// <summary>Encodes a frame.</summary>
    public int EncodeFrame(ReadOnlySpan<byte> source, Span<byte> destination, out bool isKeyFrame)
    {
        _buffer.SetLength(0L);
        var length = LoadAndEncodeImage(source, _buffer);
        _buffer.GetBuffer().AsSpan(0, length).CopyTo(destination);
        isKeyFrame = true;
        return length;
    }

    private int LoadAndEncodeImage(ReadOnlySpan<byte> source, Stream destination)
    {
        var position = (int)destination.Position;
        using (var image = Image.LoadPixelData<Bgra32>(source, _width, _height))
            _jpegEncoder.Encode(image, destination);
        destination.Flush();
        return (int)(destination.Position - position);
    }
}