// ClassicalSharp copyright 2014-2016 UnknownShadow200 | Licensed under MIT
using System;
using System.Drawing;
using ClassicalSharp.GraphicsAPI;
#if ANDROID
using Android.Graphics;
#endif

namespace ClassicalSharp {
	
	/// <summary> Represents a 2D packed texture atlas, specifically for terrain.png. </summary>
	public class TerrainAtlas2D : IDisposable {
		
		public const int ElementsPerRow = 16, RowsCount = 16;
		public const float invElementSize = 1 / 16f;
		public Bitmap AtlasBitmap;
		public int elementSize;
		IGraphicsApi gfx;
		IDrawer2D drawer;
		
		public TerrainAtlas2D( IGraphicsApi gfx, IDrawer2D drawer ) {
			this.gfx = gfx;
			this.drawer = drawer;
		}
		
		/// <summary> Updates the underlying atlas bitmap, fields, and texture. </summary>
		public void UpdateState( BlockInfo info, Bitmap bmp ) {
			if( !Platform.Is32Bpp( bmp ) ) {
				Utils.LogDebug( "Converting terrain atlas to 32bpp image" );
				drawer.ConvertTo32Bpp( ref bmp );
			}
			
			AtlasBitmap = bmp;
			elementSize = bmp.Width / ElementsPerRow;
			using( FastBitmap fastBmp = new FastBitmap( bmp, true, true ) )
				info.RecalculateSpriteBB( fastBmp );
		}
		
		/// <summary> Creates a new texture that contains the tile at the specified index. </summary>
		public int LoadTextureElement( int index ) {
			int size = elementSize;
			using( FastBitmap atlas = new FastBitmap( AtlasBitmap, true, true ) )
				using( Bitmap bmp = Platform.CreateBmp( size, size ) )
					using( FastBitmap dst = new FastBitmap( bmp, true, false ) )
			{
				int x = index % ElementsPerRow, y = index / ElementsPerRow;
				FastBitmap.MovePortion( x * size, y * size, 0, 0, atlas, dst, size );
				return gfx.CreateTexture( dst, true );
			}
		}
		
		/// <summary> Disposes of the underlying atlas bitmap and texture. </summary>
		public void Dispose() {
			if( AtlasBitmap != null )
				AtlasBitmap.Dispose();
		}
	}
}