using System;
using System.IO;
using Nerfed.Runtime.Graphics;

namespace Nerfed.Runtime.Video;

/// <summary>
/// This class takes in a filename for AV1 data in .obu (open bitstream unit) format
/// </summary>
public unsafe class VideoAV1 : GraphicsResource
{
	public string Filename { get; }

	public int Width => width;
	public int Height => height;
	public double FramesPerSecond { get; set; }
	public Dav1dfile.PixelLayout PixelLayout => pixelLayout;
	public int UVWidth { get; }
	public int UVHeight { get; }

	private int width;
	private int height;
	private Dav1dfile.PixelLayout pixelLayout;

	/// <summary>
	/// Opens an AV1 file so it can be loaded by VideoPlayer. You must also provide a playback framerate.
	/// </summary>
	public VideoAV1(GraphicsDevice device, string filename, double framesPerSecond) : base(device)
	{
		if (!File.Exists(filename))
		{
			throw new ArgumentException("Video file not found!");
		}

		if (Dav1dfile.df_fopen(filename, out IntPtr handle) == 0)
		{
			throw new Exception("Failed to open video file!");
		}

		Dav1dfile.df_videoinfo(handle, out width, out height, out pixelLayout);
		Dav1dfile.df_close(handle);

		if (pixelLayout == Dav1dfile.PixelLayout.I420)
		{
			UVWidth = Width / 2;
			UVHeight = Height / 2;
		}
		else if (pixelLayout == Dav1dfile.PixelLayout.I422)
		{
			UVWidth = Width / 2;
			UVHeight = Height;
		}
		else if (pixelLayout == Dav1dfile.PixelLayout.I444)
		{
			UVWidth = width;
			UVHeight = height;
		}
		else
		{
			throw new NotSupportedException("Unrecognized YUV format!");
		}

		FramesPerSecond = framesPerSecond;

		Filename = filename;
	}
}