using System;
using System.Collections.Generic;
using System.Drawing;
using System.Security.Cryptography;
using System.IO;
using System.Configuration;
using System.Drawing.Text;

namespace SpritePacker
{
	public class Packer
	{
		private List<Sprite> sprites = new List<Sprite>();

		public Packer()
		{
			
		}

		public void Add(Sprite sprite)
		{
			sprites.Add(sprite);
		}
		public bool Remove(Sprite sprite)
		{
			return sprites.Remove(sprite);
		}

		public void Arrange()
		{
			List<Sprite> arrangedSprites = new List<Sprite>();
			foreach(Sprite cspr in sprites)
			{
				Point scanLines = Point.Empty;
				Point nextScanLines = new Point(int.MaxValue, int.MaxValue);
				while(true)
				{
					if (!cspr.IntersectsWith(arrangedSprites))
						break;

					// Scan along the X axis
					cspr.X = 0;
					cspr.Y = scanLines.Y;

					bool foundPosition = false;
					while(cspr.X < scanLines.X)
					{
						if (!cspr.IntersectsWith(arrangedSprites))
						{
							foundPosition = true;
							break;
						}

						// Get the edge furthest to the right
						List<Sprite> problems = cspr.GetIntersectors(arrangedSprites);
						Sprite rightProblem = problems[0];
						foreach (Sprite probSpr in problems)
						{
							if (probSpr.Right > rightProblem.Right)
								rightProblem = probSpr;
							if (probSpr.Top < nextScanLines.Y)
								nextScanLines.Y = probSpr.Top + 1;
						}

						// Move up to the position furthest to the right
						// NOTE: We may need to add one here.
						cspr.X = rightProblem.Right + 1;

					}

					if (!foundPosition)
					{
						// We didn't find anything along the x axis - let's scan the y axis next
						cspr.X = scanLines.X;
						cspr.Y = 0;
						while (cspr.Y < scanLines.Y)
						{
							if (!cspr.IntersectsWith(arrangedSprites))
							{
								foundPosition = true;
								break;
							}

							// Get the edge furthest downwards
							List<Sprite> problems = cspr.GetIntersectors(arrangedSprites);
							Sprite downProblem = problems[0];
							foreach (Sprite probSpr in problems)
							{
								if (probSpr.Bottom > downProblem.Bottom)
									downProblem = probSpr;
								if (probSpr.Left < nextScanLines.X)
									nextScanLines.X = probSpr.Left + 1;
							}
							// Move up to the position furthest downwards
							cspr.Y = downProblem.Bottom + 1;
						}
					}

					// If we found a new position, then we don't need to move the scan lines up and try again
					if (foundPosition)
						break;

					// Make sure that the next scan lines are sane
					if (nextScanLines.X == int.MaxValue)
						nextScanLines.X = scanLines.X;
					if (nextScanLines.Y == int.MaxValue)
						nextScanLines.Y = scanLines.Y;

					// If the next scan lines and the current scan lines are identical,
					// then something is very wrong
					if(nextScanLines.Equals(scanLines))
						throw new Exception("Failed to find the next set of lines to scan!");

					// Move the scan lines up to the next nearest ones we've found
					scanLines = nextScanLines;
					nextScanLines = new Point(int.MaxValue, int.MaxValue);
				}

				arrangedSprites.Add(cspr);
			}

			// We don't need to copy the list of arranged sprites across to the main list here
			// because Sprite is a class and classes are passed by _reference_.
		}

		public override string ToString()
		{
			string result = string.Format("SpritePacker:");

			foreach (Sprite spr in sprites)
				result += string.Format("\t{0}\n", spr);

			return result;
		}
	}
}