using System;
using System.Collections;

namespace ProcessInfo
{
	public class ProcessListViewItemComparer : IComparer
	{
		// we need to support sort order in the IComparer because ListView only does ascending sort
		private bool ascending = true;
		private ProcessField compareField = ProcessField.Pid;
		
		public ProcessListViewItemComparer()
		{
		}

		public ProcessListViewItemComparer( ProcessField compareField, bool ascending )
		{
			this.compareField = compareField;
			this.ascending = ascending;
		}

		public int Compare( ProcessListViewItem a, ProcessListViewItem b )
		{
			if ( ( a == null ) || ( b == null ) )
			{
				throw new ArgumentNullException();
			}

			int comparison = new ProcessComparer( compareField ).Compare( a.Process, b.Process );

			if ( !ascending )
			{
				comparison *= -1;
			}

			return comparison;
		}

		int IComparer.Compare( Object a, Object b )
		{
			return this.Compare( (ProcessListViewItem)a, (ProcessListViewItem)b );
		}

		
		public bool Ascending
		{
			get { return ascending; }
			set { ascending = value; }
		}

		public ProcessField CompareField
		{
			get { return compareField; }
			set { compareField = value; }
		}
	}
}