using Editor;
using Sandbox;
using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace SpriteTools;

public static class PixmapCache
{
	static Dictionary<string, Pixmap> _cache = new Dictionary<string, Pixmap>();

	public static Pixmap Get ( string filePath, Rect rect )
	{
		var key = filePath + "?" + rect.ToString();
		if ( _cache.TryGetValue( key, out var cachedPixmap ) )
		{
			return cachedPixmap;
		}

		if ( !Sandbox.FileSystem.Mounted.FileExists( filePath ) )
		{
			return null;
		}

		var texture = Texture.LoadFromFileSystem( filePath, Sandbox.FileSystem.Mounted );
		if ( rect.Width == 0 || rect.Height == 0 )
		{
			rect = new Rect( 0, 0, texture.Width, texture.Height );
		}

		var pixmap = new Pixmap( (int)rect.Width, (int)rect.Height );
		var pixels = texture.GetPixels();
		List<Color32> span = new();
		for ( int y = (int)rect.Top; y < (int)rect.Bottom; y++ )
		{
			for ( int x = (int)rect.Left; x < (int)rect.Right; x++ )
			{
				var i = x + y * texture.Width;
				span.Add( new Color32( pixels[i].b, pixels[i].g, pixels[i].r, pixels[i].a ) );
			}
		}
		pixmap.UpdateFromPixels( MemoryMarshal.AsBytes<Color32>( span.ToArray() ), (int)rect.Width, (int)rect.Height );
		_cache[key] = pixmap;
		return pixmap;
	}

	public static void ClearCache ()
	{
		_cache.Clear();
	}
}