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using System.Collections;
using System.ComponentModel;

namespace XenAdmin.Controls.DataGridViewEx
{
    /// <summary>
    /// Abstract base class that provides a bidirectional comparator for sorting
    /// for CollapsingPoolHostDataGridViewRows
    /// </summary>
    public abstract class CollapsingPoolHostDataGridViewRowSorter : IComparer
    {
        private readonly ListSortDirection direction;
        private CollapsingPoolHostDataGridViewRow lhs;
        private CollapsingPoolHostDataGridViewRow rhs;

        protected CollapsingPoolHostDataGridViewRow Lhs
        {
            get { return lhs; }
        }

        protected CollapsingPoolHostDataGridViewRow Rhs
        {
            get { return rhs; }
        }

        protected CollapsingPoolHostDataGridViewRowSorter()
        {
            direction = ListSortDirection.Ascending;
        }

        protected CollapsingPoolHostDataGridViewRowSorter(ListSortDirection direction)
        {
            this.direction = direction;
        }

        protected ListSortDirection Direction
        {
            get { return direction; }
        }

        /// <summary>
        /// Interface member correcting the sort for the direction required
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <returns>0,1 or -1 depending on the comparison</returns>
        public int Compare(object x, object y)
        {
            if (x == null || y == null)
                return 1;

            lhs = x as CollapsingPoolHostDataGridViewRow;
            rhs = y as CollapsingPoolHostDataGridViewRow;

            if (lhs == null || rhs == null)
                return 1;

            if (direction == ListSortDirection.Ascending)
                return PerformSort();
            else
                return -1 * PerformSort();
        }

        /// <summary>
        /// Method to perform the sort on the two CollapsingPoolHostDataGridViewRows
        /// </summary>
        /// <returns></returns>
        protected abstract int PerformSort();
    }
}
