// ClassicalSharp copyright 2014-2016 UnknownShadow200 | Licensed under MIT
using System;
using System.Drawing;
using ClassicalSharp.GraphicsAPI;

namespace ClassicalSharp {
	public sealed class TextAtlas : IDisposable {
		
		public Texture tex;
		Game game;
		int[] widths;
		internal int offset, curX, totalWidth;
		
		public TextAtlas(Game game) {
			this.game = game;
		}
		
		public void Pack(string chars, Font font, string prefix) {
			DrawTextArgs args = new DrawTextArgs("", font, true);
			widths = new int[chars.Length];
			
			using(IDrawer2D drawer = game.Drawer2D) {
				args.Text = prefix;
				Size size = game.Drawer2D.MeasureChatSize(ref args);
				offset = size.Width;
				size.Width += 16 * chars.Length;
				
				using(Bitmap bmp = IDrawer2D.CreatePow2Bitmap(size)) {
					drawer.SetBitmap(bmp);
					drawer.DrawChatText(ref args, 0, 0);
					
					for (int i = 0; i < chars.Length; i++) {
						args.Text = new String(chars[i], 1);
						widths[i] = game.Drawer2D.MeasureChatSize(ref args).Width;
						drawer.DrawChatText(ref args, offset + 16 * i, 0);
					}
					
					tex = drawer.Make2DTexture(bmp, size, 0, 0);
					drawer.ReducePadding(ref tex, Utils.Floor(font.Size));
					
					tex.U2 = (float)offset / bmp.Width;
					tex.Width = (short)offset;
					totalWidth = bmp.Width;
				}
			}
		}
		
		public void Dispose() { game.Graphics.DeleteTexture(ref tex); }
		
		
		public void Add(int charIndex, VertexP3fT2fC4b[] vertices, ref int index) {
			int width = widths[charIndex];			
			Texture part = tex;
			part.X1 = curX; part.Width = (short)width;
			part.U1 = (offset + charIndex * 16) / (float)totalWidth;
			part.U2 = part.U1 + width / (float)totalWidth;
			
			curX += width;
			IGraphicsApi.Make2DQuad(ref part, FastColour.WhitePacked, 
			                        vertices, ref index);
		}
		
		public void AddInt(int value, VertexP3fT2fC4b[] vertices, ref int index) {
			if (value < 0) Add(10, vertices, ref index); // - sign
			
			int count = 0;
			value = Reverse(Math.Abs(value), out count);
			for (int i = 0; i < count; i++) {
				Add(value % 10, vertices, ref index); value /= 10;
			}
		}
		
		static int Reverse(int value, out int count) {
			int orig = value, reversed = 0;
			count = 1; value /= 10;
			while (value > 0) {
				count++; value /= 10;
			}
			
			for (int i = 0; i < count; i++) {
				reversed *= 10;
				reversed += orig % 10;
				orig /= 10;
			}
			return reversed;
		}
	}
}