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	/*
	* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package javax.swing;

	import java.awt.Component;
	import java.awt.Container;
	import java.awt.Window;
	import java.util.*;
	import java.awt.FocusTraversalPolicy;
	import sun.util.logging.PlatformLogger;
	import java.lang.reflect.InvocationTargetException;
	import java.lang.reflect.Method;
	import sun.security.action.GetPropertyAction;
	import java.security.AccessController;
	import java.security.PrivilegedAction;

	/**
	* A FocusTraversalPolicy that determines traversal order by sorting the
	* Components of a focus traversal cycle based on a given Comparator. Portions
	* of the Component hierarchy that are not visible and displayable will not be
	* included.
	* <p>
	* By default, SortingFocusTraversalPolicy implicitly transfers focus down-
	* cycle. That is, during normal focus traversal, the Component
	* traversed after a focus cycle root will be the focus-cycle-root's default
	* Component to focus. This behavior can be disabled using the
	* <code>setImplicitDownCycleTraversal</code> method.
	* <p>
	* By default, methods of this class with return a Component only if it is
	* visible, displayable, enabled, and focusable. Subclasses can modify this
	* behavior by overriding the <code>accept</code> method.
	* <p>
	* This policy takes into account <a
	* href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal
	* policy providers</a>. When searching for first/last/next/previous Component,
	* if a focus traversal policy provider is encountered, its focus traversal
	* policy is used to perform the search operation.
	*
	* @author David Mendenhall
	*
	* @see java.util.Comparator
	* @since 1.4
	*/
	public class SortingFocusTraversalPolicy
	extends InternalFrameFocusTraversalPolicy
	{
	private Comparator<? super Component> comparator;
	private boolean implicitDownCycleTraversal = true;

	private PlatformLogger log = PlatformLogger.getLogger("javax.swing.SortingFocusTraversalPolicy");

	/**
	* Used by getComponentAfter and getComponentBefore for efficiency. In
	* order to maintain compliance with the specification of
	* FocusTraversalPolicy, if traversal wraps, we should invoke
	* getFirstComponent or getLastComponent. These methods may be overriden in
	* subclasses to behave in a non-generic way. However, in the generic case,
	* these methods will simply return the first or last Components of the
	* sorted list, respectively. Since getComponentAfter and
	* getComponentBefore have already built the sorted list before determining
	* that they need to invoke getFirstComponent or getLastComponent, the
	* sorted list should be reused if possible.
	*/
	transient private Container cachedRoot;
	transient private List<Component> cachedCycle;

	// Delegate our fitness test to ContainerOrder so that we only have to
	// code the algorithm once.
	private static final SwingContainerOrderFocusTraversalPolicy
	fitnessTestPolicy = new SwingContainerOrderFocusTraversalPolicy();

	final private int FORWARD_TRAVERSAL = 0;
	final private int BACKWARD_TRAVERSAL = 1;

	/*
	* When true (by default), the legacy merge-sort algo is used to sort an FTP cycle.
	* When false, the default (tim-sort) algo is used, which may lead to an exception.
	* See: JDK-8048887
	*/
	private static final boolean legacySortingFTPEnabled;
	private static final Method legacyMergeSortMethod;

	static {
	legacySortingFTPEnabled = "true".equals(AccessController.doPrivileged(
	new GetPropertyAction("swing.legacySortingFTPEnabled", "true")));
	legacyMergeSortMethod = legacySortingFTPEnabled ?
	AccessController.doPrivileged(new PrivilegedAction<Method>() {
	public Method run() {
	try {
	Class c = Class.forName("java.util.Arrays");
	Method m = c.getDeclaredMethod("legacyMergeSort", new Class[]{Object[].class, Comparator.class});
	m.setAccessible(true);
	return m;
	} catch (ClassNotFoundException \| NoSuchMethodException e) {
	// using default sorting algo
	return null;
	}
	}
	}) :
	null;
	}

	/**
	* Constructs a SortingFocusTraversalPolicy without a Comparator.
	* Subclasses must set the Comparator using <code>setComparator</code>
	* before installing this FocusTraversalPolicy on a focus cycle root or
	* KeyboardFocusManager.
	*/
	protected SortingFocusTraversalPolicy() {
	}

	/**
	* Constructs a SortingFocusTraversalPolicy with the specified Comparator.
	*/
	public SortingFocusTraversalPolicy(Comparator<? super Component> comparator) {
	this.comparator = comparator;
	}

	private List<Component> getFocusTraversalCycle(Container aContainer) {
	List<Component> cycle = new ArrayList<Component>();
	enumerateAndSortCycle(aContainer, cycle);
	return cycle;
	}
	private int getComponentIndex(List<Component> cycle, Component aComponent) {
	int index;
	try {
	index = Collections.binarySearch(cycle, aComponent, comparator);
	} catch (ClassCastException e) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### During the binary search for " + aComponent + " the exception occurred: ", e);
	}
	return -1;
	}
	if (index < 0) {
	// Fix for 5070991.
	// A workaround for a transitivity problem caused by ROW_TOLERANCE,
	// because of that the component may be missed in the binary search.
	// Try to search it again directly.
	index = cycle.indexOf(aComponent);
	}
	return index;
	}

	private void enumerateAndSortCycle(Container focusCycleRoot, List<Component> cycle) {
	if (focusCycleRoot.isShowing()) {
	enumerateCycle(focusCycleRoot, cycle);
	if (!legacySortingFTPEnabled \|\|
	!legacySort(cycle, comparator))
	{
	Collections.sort(cycle, comparator);
	}
	}
	}

	private boolean legacySort(List<Component> l, Comparator<? super Component> c) {
	if (legacyMergeSortMethod == null)
	return false;

	Object[] a = l.toArray();
	try {
	legacyMergeSortMethod.invoke(null, a, c);
	} catch (IllegalAccessException \| InvocationTargetException e) {
	return false;
	}
	ListIterator<Component> i = l.listIterator();
	for (Object e : a) {
	i.next();
	i.set((Component)e);
	}
	return true;
	}

	private void enumerateCycle(Container container, List<Component> cycle) {
	if (!(container.isVisible() && container.isDisplayable())) {
	return;
	}

	cycle.add(container);

	Component[] components = container.getComponents();
	for (Component comp : components) {
	if (comp instanceof Container) {
	Container cont = (Container)comp;

	if (!cont.isFocusCycleRoot() &&
	!cont.isFocusTraversalPolicyProvider() &&
	!((cont instanceof JComponent) && ((JComponent)cont).isManagingFocus()))
	{
	enumerateCycle(cont, cycle);
	continue;
	}
	}
	cycle.add(comp);
	}
	}

	Container getTopmostProvider(Container focusCycleRoot, Component aComponent) {
	Container aCont = aComponent.getParent();
	Container ftp = null;
	while (aCont != focusCycleRoot && aCont != null) {
	if (aCont.isFocusTraversalPolicyProvider()) {
	ftp = aCont;
	}
	aCont = aCont.getParent();
	}
	if (aCont == null) {
	return null;
	}
	return ftp;
	}

	/*
	* Checks if a new focus cycle takes place and returns a Component to traverse focus to.
	* @param comp a possible focus cycle root or policy provider
	* @param traversalDirection the direction of the traversal
	* @return a Component to traverse focus to if {@code comp} is a root or provider
	* and implicit down-cycle is set, otherwise {@code null}
	*/
	private Component getComponentDownCycle(Component comp, int traversalDirection) {
	Component retComp = null;

	if (comp instanceof Container) {
	Container cont = (Container)comp;

	if (cont.isFocusCycleRoot()) {
	if (getImplicitDownCycleTraversal()) {
	retComp = cont.getFocusTraversalPolicy().getDefaultComponent(cont);

	if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Transfered focus down-cycle to " + retComp +
	" in the focus cycle root " + cont);
	}
	} else {
	return null;
	}
	} else if (cont.isFocusTraversalPolicyProvider()) {
	retComp = (traversalDirection == FORWARD_TRAVERSAL ?
	cont.getFocusTraversalPolicy().getDefaultComponent(cont) :
	cont.getFocusTraversalPolicy().getLastComponent(cont));

	if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Transfered focus to " + retComp + " in the FTP provider " + cont);
	}
	}
	}
	return retComp;
	}

	/**
	* Returns the Component that should receive the focus after aComponent.
	* aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
	* <p>
	* By default, SortingFocusTraversalPolicy implicitly transfers focus down-
	* cycle. That is, during normal focus traversal, the Component
	* traversed after a focus cycle root will be the focus-cycle-root's
	* default Component to focus. This behavior can be disabled using the
	* <code>setImplicitDownCycleTraversal</code> method.
	* <p>
	* If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
	* traversal policy provider</a>, the focus is always transferred down-cycle.
	*
	* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
	* @param aComponent a (possibly indirect) child of aContainer, or
	* aContainer itself
	* @return the Component that should receive the focus after aComponent, or
	* null if no suitable Component can be found
	* @throws IllegalArgumentException if aContainer is not a focus cycle
	* root of aComponent or a focus traversal policy provider, or if either aContainer or
	* aComponent is null
	*/
	public Component getComponentAfter(Container aContainer, Component aComponent) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Searching in " + aContainer + " for component after " + aComponent);
	}

	if (aContainer == null \|\| aComponent == null) {
	throw new IllegalArgumentException("aContainer and aComponent cannot be null");
	}
	if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
	throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");

	} else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
	throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
	}

	// Before all the ckecks below we first see if it's an FTP provider or a focus cycle root.
	// If it's the case just go down cycle (if it's set to "implicit").
	Component comp = getComponentDownCycle(aComponent, FORWARD_TRAVERSAL);
	if (comp != null) {
	return comp;
	}

	// See if the component is inside of policy provider.
	Container provider = getTopmostProvider(aContainer, aComponent);
	if (provider != null) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Asking FTP " + provider + " for component after " + aComponent);
	}

	// FTP knows how to find component after the given. We don't.
	FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
	Component afterComp = policy.getComponentAfter(provider, aComponent);

	// Null result means that we overstepped the limit of the FTP's cycle.
	// In that case we must quit the cycle, otherwise return the component found.
	if (afterComp != null) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### FTP returned " + afterComp);
	}
	return afterComp;
	}
	aComponent = provider;
	}

	List<Component> cycle = getFocusTraversalCycle(aContainer);

	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Cycle is " + cycle + ", component is " + aComponent);
	}

	int index = getComponentIndex(cycle, aComponent);

	if (index < 0) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
	}
	return getFirstComponent(aContainer);
	}

	for (index++; index < cycle.size(); index++) {
	comp = cycle.get(index);
	if (accept(comp)) {
	return comp;
	} else if ((comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null) {
	return comp;
	}
	}

	if (aContainer.isFocusCycleRoot()) {
	this.cachedRoot = aContainer;
	this.cachedCycle = cycle;

	comp = getFirstComponent(aContainer);

	this.cachedRoot = null;
	this.cachedCycle = null;

	return comp;
	}
	return null;
	}

	/**
	* Returns the Component that should receive the focus before aComponent.
	* aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
	* <p>
	* By default, SortingFocusTraversalPolicy implicitly transfers focus down-
	* cycle. That is, during normal focus traversal, the Component
	* traversed after a focus cycle root will be the focus-cycle-root's
	* default Component to focus. This behavior can be disabled using the
	* <code>setImplicitDownCycleTraversal</code> method.
	* <p>
	* If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
	* traversal policy provider</a>, the focus is always transferred down-cycle.
	*
	* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
	* @param aComponent a (possibly indirect) child of aContainer, or
	* aContainer itself
	* @return the Component that should receive the focus before aComponent,
	* or null if no suitable Component can be found
	* @throws IllegalArgumentException if aContainer is not a focus cycle
	* root of aComponent or a focus traversal policy provider, or if either aContainer or
	* aComponent is null
	*/
	public Component getComponentBefore(Container aContainer, Component aComponent) {
	if (aContainer == null \|\| aComponent == null) {
	throw new IllegalArgumentException("aContainer and aComponent cannot be null");
	}
	if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
	throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");

	} else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
	throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
	}

	// See if the component is inside of policy provider.
	Container provider = getTopmostProvider(aContainer, aComponent);
	if (provider != null) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Asking FTP " + provider + " for component after " + aComponent);
	}

	// FTP knows how to find component after the given. We don't.
	FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
	Component beforeComp = policy.getComponentBefore(provider, aComponent);

	// Null result means that we overstepped the limit of the FTP's cycle.
	// In that case we must quit the cycle, otherwise return the component found.
	if (beforeComp != null) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### FTP returned " + beforeComp);
	}
	return beforeComp;
	}
	aComponent = provider;

	// If the provider is traversable it's returned.
	if (accept(aComponent)) {
	return aComponent;
	}
	}

	List<Component> cycle = getFocusTraversalCycle(aContainer);

	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Cycle is " + cycle + ", component is " + aComponent);
	}

	int index = getComponentIndex(cycle, aComponent);

	if (index < 0) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
	}
	return getLastComponent(aContainer);
	}

	Component comp;
	Component tryComp;

	for (index--; index>=0; index--) {
	comp = cycle.get(index);
	if (comp != aContainer && (tryComp = getComponentDownCycle(comp, BACKWARD_TRAVERSAL)) != null) {
	return tryComp;
	} else if (accept(comp)) {
	return comp;
	}
	}

	if (aContainer.isFocusCycleRoot()) {
	this.cachedRoot = aContainer;
	this.cachedCycle = cycle;

	comp = getLastComponent(aContainer);

	this.cachedRoot = null;
	this.cachedCycle = null;

	return comp;
	}
	return null;
	}

	/**
	* Returns the first Component in the traversal cycle. This method is used
	* to determine the next Component to focus when traversal wraps in the
	* forward direction.
	*
	* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose
	* first Component is to be returned
	* @return the first Component in the traversal cycle of aContainer,
	* or null if no suitable Component can be found
	* @throws IllegalArgumentException if aContainer is null
	*/
	public Component getFirstComponent(Container aContainer) {
	List<Component> cycle;

	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Getting first component in " + aContainer);
	}
	if (aContainer == null) {
	throw new IllegalArgumentException("aContainer cannot be null");
	}

	if (this.cachedRoot == aContainer) {
	cycle = this.cachedCycle;
	} else {
	cycle = getFocusTraversalCycle(aContainer);
	}

	if (cycle.size() == 0) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Cycle is empty");
	}
	return null;
	}
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Cycle is " + cycle);
	}

	for (Component comp : cycle) {
	if (accept(comp)) {
	return comp;
	} else if (comp != aContainer &&
	(comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null)
	{
	return comp;
	}
	}
	return null;
	}

	/**
	* Returns the last Component in the traversal cycle. This method is used
	* to determine the next Component to focus when traversal wraps in the
	* reverse direction.
	*
	* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose
	* last Component is to be returned
	* @return the last Component in the traversal cycle of aContainer,
	* or null if no suitable Component can be found
	* @throws IllegalArgumentException if aContainer is null
	*/
	public Component getLastComponent(Container aContainer) {
	List<Component> cycle;
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Getting last component in " + aContainer);
	}

	if (aContainer == null) {
	throw new IllegalArgumentException("aContainer cannot be null");
	}

	if (this.cachedRoot == aContainer) {
	cycle = this.cachedCycle;
	} else {
	cycle = getFocusTraversalCycle(aContainer);
	}

	if (cycle.size() == 0) {
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Cycle is empty");
	}
	return null;
	}
	if (log.isLoggable(PlatformLogger.Level.FINE)) {
	log.fine("### Cycle is " + cycle);
	}

	for (int i= cycle.size() - 1; i >= 0; i--) {
	Component comp = cycle.get(i);
	if (accept(comp)) {
	return comp;
	} else if (comp instanceof Container && comp != aContainer) {
	Container cont = (Container)comp;
	if (cont.isFocusTraversalPolicyProvider()) {
	Component retComp = cont.getFocusTraversalPolicy().getLastComponent(cont);
	if (retComp != null) {
	return retComp;
	}
	}
	}
	}
	return null;
	}

	/**
	* Returns the default Component to focus. This Component will be the first
	* to receive focus when traversing down into a new focus traversal cycle
	* rooted at aContainer. The default implementation of this method
	* returns the same Component as <code>getFirstComponent</code>.
	*
	* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose
	* default Component is to be returned
	* @return the default Component in the traversal cycle of aContainer,
	* or null if no suitable Component can be found
	* @see #getFirstComponent
	* @throws IllegalArgumentException if aContainer is null
	*/
	public Component getDefaultComponent(Container aContainer) {
	return getFirstComponent(aContainer);
	}

	/**
	* Sets whether this SortingFocusTraversalPolicy transfers focus down-cycle
	* implicitly. If <code>true</code>, during normal focus traversal,
	* the Component traversed after a focus cycle root will be the focus-
	* cycle-root's default Component to focus. If <code>false</code>, the
	* next Component in the focus traversal cycle rooted at the specified
	* focus cycle root will be traversed instead. The default value for this
	* property is <code>true</code>.
	*
	* @param implicitDownCycleTraversal whether this
	* SortingFocusTraversalPolicy transfers focus down-cycle implicitly
	* @see #getImplicitDownCycleTraversal
	* @see #getFirstComponent
	*/
	public void setImplicitDownCycleTraversal(boolean implicitDownCycleTraversal) {
	this.implicitDownCycleTraversal = implicitDownCycleTraversal;
	}

	/**
	* Returns whether this SortingFocusTraversalPolicy transfers focus down-
	* cycle implicitly. If <code>true</code>, during normal focus
	* traversal, the Component traversed after a focus cycle root will be the
	* focus-cycle-root's default Component to focus. If <code>false</code>,
	* the next Component in the focus traversal cycle rooted at the specified
	* focus cycle root will be traversed instead.
	*
	* @return whether this SortingFocusTraversalPolicy transfers focus down-
	* cycle implicitly
	* @see #setImplicitDownCycleTraversal
	* @see #getFirstComponent
	*/
	public boolean getImplicitDownCycleTraversal() {
	return implicitDownCycleTraversal;
	}

	/**
	* Sets the Comparator which will be used to sort the Components in a
	* focus traversal cycle.
	*
	* @param comparator the Comparator which will be used for sorting
	*/
	protected void setComparator(Comparator<? super Component> comparator) {
	this.comparator = comparator;
	}

	/**
	* Returns the Comparator which will be used to sort the Components in a
	* focus traversal cycle.
	*
	* @return the Comparator which will be used for sorting
	*/
	protected Comparator<? super Component> getComparator() {
	return comparator;
	}

	/**
	* Determines whether a Component is an acceptable choice as the new
	* focus owner. By default, this method will accept a Component if and
	* only if it is visible, displayable, enabled, and focusable.
	*
	* @param aComponent the Component whose fitness as a focus owner is to
	* be tested
	* @return <code>true</code> if aComponent is visible, displayable,
	* enabled, and focusable; <code>false</code> otherwise
	*/
	protected boolean accept(Component aComponent) {
	return fitnessTestPolicy.accept(aComponent);
	}
	}

	// Create our own subclass and change accept to public so that we can call
	// accept.
	class SwingContainerOrderFocusTraversalPolicy
	extends java.awt.ContainerOrderFocusTraversalPolicy
	{
	public boolean accept(Component aComponent) {
	return super.accept(aComponent);
	}
	}

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