/*
 * Copyright (c) 2000, 2008, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */
package javax.swing;

import java.util.Comparator;
import java.util.LinkedList;
import java.util.ListIterator;
import java.awt.Component;
import java.awt.ComponentOrientation;
import java.awt.Window;


/**
 * Comparator which attempts to sort Components based on their size and
 * position. Code adapted from original javax.swing.DefaultFocusManager
 * implementation.
 *
 * @author David Mendenhall
 */
final class LayoutComparator implements Comparator<Component>, java.io.Serializable {

 private static final int ROW_TOLERANCE = 10;

 private boolean horizontal = true;
 private boolean leftToRight = true;

 void setComponentOrientation(ComponentOrientation orientation) {
 horizontal = orientation.isHorizontal();
 leftToRight = orientation.isLeftToRight();
 }

 public int compare(Component a, Component b) {
 if (a == b) {
 return 0;
 }

 // Row/Column algorithm only applies to siblings. If 'a' and 'b'
 // aren't siblings, then we need to find their most inferior
 // ancestors which share a parent. Compute the ancestory lists for
 // each Component and then search from the Window down until the
 // hierarchy branches.
 if (a.getParent() != b.getParent()) {
 LinkedList<Component> aAncestory = new LinkedList<Component>();

 for(; a != null; a = a.getParent()) {
 aAncestory.add(a);
 if (a instanceof Window) {
 break;
 }
 }
 if (a == null) {
 // 'a' is not part of a Window hierarchy. Can't cope.
 throw new ClassCastException();
 }

 LinkedList<Component> bAncestory = new LinkedList<Component>();

 for(; b != null; b = b.getParent()) {
 bAncestory.add(b);
 if (b instanceof Window) {
 break;
 }
 }
 if (b == null) {
 // 'b' is not part of a Window hierarchy. Can't cope.
 throw new ClassCastException();
 }

 for (ListIterator<Component>
 aIter = aAncestory.listIterator(aAncestory.size()),
 bIter = bAncestory.listIterator(bAncestory.size()); ;) {
 if (aIter.hasPrevious()) {
 a = aIter.previous();
 } else {
 // a is an ancestor of b
 return -1;
 }

 if (bIter.hasPrevious()) {
 b = bIter.previous();
 } else {
 // b is an ancestor of a
 return 1;
 }

 if (a != b) {
 break;
 }
 }
 }

 int ax = a.getX(), ay = a.getY(), bx = b.getX(), by = b.getY();

 int zOrder = a.getParent().getComponentZOrder(a) - b.getParent().getComponentZOrder(b);
 if (horizontal) {
 if (leftToRight) {

 // LT - Western Europe (optional for Japanese, Chinese, Korean)

 if (Math.abs(ay - by) < ROW_TOLERANCE) {
 return (ax < bx) ? -1 : ((ax > bx) ? 1 : zOrder);
 } else {
 return (ay < by) ? -1 : 1;
 }
 } else { // !leftToRight

 // RT - Middle East (Arabic, Hebrew)

 if (Math.abs(ay - by) < ROW_TOLERANCE) {
 return (ax > bx) ? -1 : ((ax < bx) ? 1 : zOrder);
 } else {
 return (ay < by) ? -1 : 1;
 }
 }
 } else { // !horizontal
 if (leftToRight) {

 // TL - Mongolian

 if (Math.abs(ax - bx) < ROW_TOLERANCE) {
 return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
 } else {
 return (ax < bx) ? -1 : 1;
 }
 } else { // !leftToRight

 // TR - Japanese, Chinese, Korean

 if (Math.abs(ax - bx) < ROW_TOLERANCE) {
 return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder);
 } else {
 return (ax > bx) ? -1 : 1;
 }
 }
 }
 }
}