/*
 * Copyright © 2005, Mathew Hall
 * All rights reserved.
 * 
 * Sort algorithm modified from the C# implementation written by Jonathan de Halleux, 
 * Marc Clifton, and Robert Rohde (see http://www.codeproject.com/csharp/cssorters.asp) 
 * based on Java implementations by James Gosling, Jason Harrison, Jack Snoeyink, Jim Boritz, 
 * Denis Ahrens, Alvin Raj (see http://www.cs.ubc.ca/spider/harrison/Java/sorting-demo.html).
 *
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 *
 *    - Redistributions of source code must retain the above copyright notice, 
 *      this list of conditions and the following disclaimer.
 * 
 *    - Redistributions in binary form must reproduce the above copyright notice, 
 *      this list of conditions and the following disclaimer in the documentation 
 *      and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
 * IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, 
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
 * OF SUCH DAMAGE.
 */


using System;
using System.Collections;
using System.Windows.Forms;

using XPTable.Models;


namespace XPTable.Sorting
{
	/// <summary>
	/// A HeapSort implementation for sorting the Cells contained in a TableModel
	/// </summary>
	public class HeapSorter : SorterBase
	{
		/// <summary>
		/// Initializes a new instance of the HeapSorter class with the specified 
		/// TableModel, Column index, IComparer and SortOrder
		/// </summary>
		/// <param name="tableModel">The TableModel that contains the data to be sorted</param>
		/// <param name="column">The index of the Column to be sorted</param>
		/// <param name="comparer">The IComparer used to sort the Column's Cells</param>
		/// <param name="sortOrder">Specifies how the Column is to be sorted</param>
		public HeapSorter(TableModel tableModel, int column, IComparer comparer, SortOrder sortOrder) : base(tableModel, column, comparer, sortOrder)
		{
			
		}

		
		/// <summary>
		/// Starts sorting the Cells in the TableModel
		/// </summary>
		public override void Sort()
		{
			int n;
			int i;

			n = this.TableModel.Rows.Count;

			for (i=n/2; i>0; i--) 
			{
				this.DownHeap(i, n);
			}
			do 
			{
				this.Swap(0, n-1);

				n = n - 1;

				this.DownHeap(1, n);
			} while (n>1);
		}


		/// <summary>
		/// 
		/// </summary>
		/// <param name="k"></param>
		/// <param name="n"></param>
		private void DownHeap(int k, int n)
		{
			int j;
			bool loop = true;

			while ((k <= n / 2) && loop) 
			{
				j = k + k;

				if (j < n) 
				{
					if (this.Compare(this.TableModel[j-1, this.SortColumn], this.TableModel[j, this.SortColumn]) < 0) 
					{					
						j++;
					}
				}	

				if (this.Compare(this.TableModel[k-1, this.SortColumn], this.TableModel[j-1, this.SortColumn]) >= 0) 
				{
					loop = false;
				} 
				else 
				{
					this.Swap(k-1, j-1);
					
					k = j;
				}
			}
		}
	}
}
