/*
 * MoveListItemStrategy.java
 *
 * Copyright (C) 2002-2009 Takis Diakoumis
 *
 * 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 3
 * of the License, or 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/>.
 *
 */

package org.underworldlabs.swing;

import java.util.List;

/**
 *
 * @author   Takis Diakoumis
 * @version  $Revision: 1460 $
 * @date     $Date: 2009-01-25 11:06:46 +1100 (Sun, 25 Jan 2009) $
 */
public class MoveListItemStrategy<T> {

    private List<T> list;
    
    private static final int MOVE_DOWN = 1;
    
    private static final int MOVE_UP = -1;
    
    public void setList(List<T> list) {

        this.list = list;
    }

    public int moveDown(int index) {

        if (canMoveDown(index)) {
        
            return moveIndex(MOVE_DOWN, index);
        }
        
        return index;
    }

    private boolean canMoveDown(int index) {

        return (index != -1 && index < list.size() - 1) ;
    }

    public int moveUp(int index) {

        if (canMoveUp(index)) {

            return moveIndex(MOVE_UP, index);
        }
        
        return index;
    }

    private boolean canMoveUp(int index) {

        return (index > 0);
    }

    private int moveIndex(int increment, int index) {

        T element = list.get(index);

        list.remove(index);

        int newIndex = index + increment;
        list.add(newIndex, element);
        
        return newIndex;
    }

}






