/*
 * Greenshot - a free and open source screenshot tool
 * Copyright (C) 2007-2015 Thomas Braun, Jens Klingen, Robin Krom
 *
 * For more information see: http://getgreenshot.org/
 * The Greenshot project is hosted on Sourceforge: http://sourceforge.net/projects/greenshot/
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 1 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

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

namespace GreenshotPlugin.Controls
{
    /// <summary>
    /// This class is an implementation of the 'IComparer' interface.
    /// </summary>
    internal class GreenshotColumnSorter : IComparer
    {
        /// <summary>
        /// Specifies the column to be sorted
        /// </summary>
        private int _columnToSort;
        /// <summary>
        /// Specifies the order in which to sort (i.e. 'Ascending').
        /// </summary>
        private SortOrder _orderOfSort;
        /// <summary>
        /// Case insensitive comparer object
        /// </summary>
        private readonly CaseInsensitiveComparer _objectCompare;

        /// <summary>
        /// Class constructor.  Initializes various elements
        /// </summary>
        public GreenshotColumnSorter()
        {
            // Initialize the column to '0'
            _columnToSort = 0;

            // Initialize the sort order to 'none'
            _orderOfSort = SortOrder.None;

            // Initialize the CaseInsensitiveComparer object
            _objectCompare = new CaseInsensitiveComparer();
        }

        /// <summary>
        /// This method is inherited from the IComparer interface.  It compares the two objects passed using a case insensitive comparison.
        /// </summary>
        /// <param name="x">First object to be compared</param>
        /// <param name="y">Second object to be compared</param>
        /// <returns>The result of the comparison. "0" if equal, negative if 'x' is less than 'y' and positive if 'x' is greater than 'y'</returns>
        public int Compare(object x, object y)
        {
            if (x == null && y == null)
            {
                return 0;
            }
            if (x == null)
            {
                return -1;
            }
            if (y == null)
            {
                return 1;
            }
            // Cast the objects to be compared to ListViewItem objects
            var listviewX = (ListViewItem)x;
            var listviewY = (ListViewItem)y;

            // Compare the two items
            var compareResult = _objectCompare.Compare(listviewX.SubItems[_columnToSort].Text, listviewY.SubItems[_columnToSort].Text);

            // Calculate correct return value based on object comparison
            if (_orderOfSort == SortOrder.Ascending)
            {
                // Ascending sort is selected, return normal result of compare operation
                return compareResult;
            }
            if (_orderOfSort == SortOrder.Descending)
            {
                // Descending sort is selected, return negative result of compare operation
                return (-compareResult);
            }

            // Return '0' to indicate they are equal
            return 0;
        }

        /// <summary>
        /// Gets or sets the number of the column to which to apply the sorting operation (Defaults to '0').
        /// </summary>
        public int SortColumn
        {
            set
            {
                _columnToSort = value;
            }
            get
            {
                return _columnToSort;
            }
        }

        /// <summary>
        /// Gets or sets the order of sorting to apply (for example, 'Ascending' or 'Descending').
        /// </summary>
        public SortOrder Order
        {
            set
            {
                _orderOfSort = value;
            }
            get
            {
                return _orderOfSort;
            }
        }
    }
}