using Dashboard.Pal;

namespace Dashboard.Drawing
{
    public record ImageData(
        TextureType Type,
        PixelFormat Format,
        int Width,
        int Height,
        byte[] Bitmap)
    {
        public int Depth { get; init; } = 1;
        public int Levels { get; init; } = 1;
        public bool Premultiplied { get; init; } = false;
        public int Alignment { get; init; } = 4;

        public long GetLevelOffset(int level)
        {
            ArgumentOutOfRangeException.ThrowIfLessThan(level, 0, nameof(level));
            ArgumentOutOfRangeException.ThrowIfGreaterThan(level, Levels, nameof(level));
            ArgumentOutOfRangeException.ThrowIfGreaterThan(level, Math.ILogB(Math.Max(Width, Height)));

            long offset = 0;

            long row = Width * Format switch
            {
                PixelFormat.R8I => 1,
                PixelFormat.R16F => 2,
                PixelFormat.Rg8I => 2,
                PixelFormat.Rg16F => 4,
                PixelFormat.Rgb8I => 3,
                PixelFormat.Rgb16F => 6,
                PixelFormat.Rgba8I => 4,
                PixelFormat.Rgba16F => 8,
            };

            row += Alignment - (row % Alignment);
            long plane = row * Height;
            long volume = plane * Depth;

            for (int i = 0; i < level; i++)
            {
                if (Depth == 1)
                {
                    offset += plane / (1 << i) / (1 << i);
                }
                else
                {
                    offset += volume / (1 << i) / (1 << i) / (1 << i);
                }
            }

            return offset;
        }
    }

    public interface IImageLoader : IApplicationExtension
    {
        public ImageData LoadImageData(Stream stream);
    }
}