/*
 * $Id$
 *
 * Copyright (c) 2005 by Rodney Kinney
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License (LGPL) as published by the Free Software Foundation.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, copies are available
 * at http://www.opensource.org.
 */
package VASSAL.counters;

import java.util.Comparator;

/**
 * Sorts GamePieces according to their position:
 * If on different Maps, order by Map id
 * If in different Stacks order by Stack position on the Map
 * If in the same Stack, order by position within the Stack
 */
public class PieceSorter implements Comparator<GamePiece> {
  public int compare(GamePiece p1, GamePiece p2) {
    if (p1.getMap() == null) {
      return p2.getMap() == null ? 0 : 1;
    }
    else if (p2.getMap() == null) {
      return -1;
    }

    if (p1.getMap() != p2.getMap()) {
      return p1.getMap().getId().compareTo(p2.getMap().getId());
    }

    final Stack s1 = p1 instanceof Stack ? (Stack) p1 : p1.getParent();
    final Stack s2 = p2 instanceof Stack ? (Stack) p2 : p2.getParent();

    if (s1 == null) {
      return s2 == null ? 0 : 1;
    }
    else if (s2 == null) {
      return -1;
    }
    else {
      int result = p1.getMap().indexOf(s1) - p2.getMap().indexOf(s2);
      if (result == 0) { // Pieces must be in the same stack
        result = s1.indexOf(p1) - s2.indexOf(p2);
      }
      return result;
    }
  }
}