/*
 * Copyright (c) 1997, 2014, 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.plaf.basic;

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.plaf.*;
import javax.swing.plaf.basic.*;
import javax.swing.border.*;

import java.applet.Applet;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.KeyboardFocusManager;
import java.awt.Window;
import java.awt.event.*;
import java.awt.AWTEvent;
import java.awt.Toolkit;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeEvent;

import java.util.*;

import sun.swing.DefaultLookup;
import sun.swing.UIAction;

import sun.awt.AppContext;

/**
 * A Windows L&amp;F implementation of PopupMenuUI.  This implementation
 * is a "combined" view/controller.
 *
 * @author Georges Saab
 * @author David Karlton
 * @author Arnaud Weber
 */
public class BasicPopupMenuUI extends PopupMenuUI {
    static final StringBuilder MOUSE_GRABBER_KEY = new StringBuilder(
                   "javax.swing.plaf.basic.BasicPopupMenuUI.MouseGrabber");
    static final StringBuilder MENU_KEYBOARD_HELPER_KEY = new StringBuilder(
                   "javax.swing.plaf.basic.BasicPopupMenuUI.MenuKeyboardHelper");

    /**
     * The instance of {@code JPopupMenu}.
     */
    protected JPopupMenu popupMenu = null;
    private transient PopupMenuListener popupMenuListener = null;
    private MenuKeyListener menuKeyListener = null;

    private static boolean checkedUnpostPopup;
    private static boolean unpostPopup;

    /**
     * Constructs a new instance of {@code BasicPopupMenuUI}.
     *
     * @param x a component
     * @return a new instance of {@code BasicPopupMenuUI}
     */
    public static ComponentUI createUI(JComponent x) {
        return new BasicPopupMenuUI();
    }

    /**
     * Constructs a new instance of {@code BasicPopupMenuUI}.
     */
    public BasicPopupMenuUI() {
        BasicLookAndFeel.needsEventHelper = true;
        LookAndFeel laf = UIManager.getLookAndFeel();
        if (laf instanceof BasicLookAndFeel) {
            ((BasicLookAndFeel)laf).installAWTEventListener();
        }
    }

    public void installUI(JComponent c) {
        popupMenu = (JPopupMenu) c;

        installDefaults();
        installListeners();
        installKeyboardActions();
    }

    /**
     * Installs default properties.
     */
    public void installDefaults() {
        if (popupMenu.getLayout() == null ||
            popupMenu.getLayout() instanceof UIResource)
            popupMenu.setLayout(new DefaultMenuLayout(popupMenu, BoxLayout.Y_AXIS));

        LookAndFeel.installProperty(popupMenu, "opaque", Boolean.TRUE);
        LookAndFeel.installBorder(popupMenu, "PopupMenu.border");
        LookAndFeel.installColorsAndFont(popupMenu,
                "PopupMenu.background",
                "PopupMenu.foreground",
                "PopupMenu.font");
    }

    /**
     * Registers listeners.
     */
    protected void installListeners() {
        if (popupMenuListener == null) {
            popupMenuListener = new BasicPopupMenuListener();
        }
        popupMenu.addPopupMenuListener(popupMenuListener);

        if (menuKeyListener == null) {
            menuKeyListener = new BasicMenuKeyListener();
        }
        popupMenu.addMenuKeyListener(menuKeyListener);

        AppContext context = AppContext.getAppContext();
        synchronized (MOUSE_GRABBER_KEY) {
            MouseGrabber mouseGrabber = (MouseGrabber)context.get(
                                                     MOUSE_GRABBER_KEY);
            if (mouseGrabber == null) {
                mouseGrabber = new MouseGrabber();
                context.put(MOUSE_GRABBER_KEY, mouseGrabber);
            }
        }
        synchronized (MENU_KEYBOARD_HELPER_KEY) {
            MenuKeyboardHelper helper =
                    (MenuKeyboardHelper)context.get(MENU_KEYBOARD_HELPER_KEY);
            if (helper == null) {
                helper = new MenuKeyboardHelper();
                context.put(MENU_KEYBOARD_HELPER_KEY, helper);
                MenuSelectionManager msm = MenuSelectionManager.defaultManager();
                msm.addChangeListener(helper);
            }
        }
    }

    /**
     * Registers keyboard actions.
     */
    protected void installKeyboardActions() {
    }

    static InputMap getInputMap(JPopupMenu popup, JComponent c) {
        InputMap windowInputMap = null;
        Object[] bindings = (Object[])UIManager.get("PopupMenu.selectedWindowInputMapBindings");
        if (bindings != null) {
            windowInputMap = LookAndFeel.makeComponentInputMap(c, bindings);
            if (!popup.getComponentOrientation().isLeftToRight()) {
                Object[] km = (Object[])UIManager.get("PopupMenu.selectedWindowInputMapBindings.RightToLeft");
                if (km != null) {
                    InputMap rightToLeftInputMap = LookAndFeel.makeComponentInputMap(c, km);
                    rightToLeftInputMap.setParent(windowInputMap);
                    windowInputMap = rightToLeftInputMap;
                }
            }
        }
        return windowInputMap;
    }

    static ActionMap getActionMap() {
        return LazyActionMap.getActionMap(BasicPopupMenuUI.class,
                                          "PopupMenu.actionMap");
    }

    static void loadActionMap(LazyActionMap map) {
        map.put(new Actions(Actions.CANCEL));
        map.put(new Actions(Actions.SELECT_NEXT));
        map.put(new Actions(Actions.SELECT_PREVIOUS));
        map.put(new Actions(Actions.SELECT_PARENT));
        map.put(new Actions(Actions.SELECT_CHILD));
        map.put(new Actions(Actions.RETURN));
        BasicLookAndFeel.installAudioActionMap(map);
    }

    public void uninstallUI(JComponent c) {
        uninstallDefaults();
        uninstallListeners();
        uninstallKeyboardActions();

        popupMenu = null;
    }

    /**
     * Uninstalls default properties.
     */
    protected void uninstallDefaults() {
        LookAndFeel.uninstallBorder(popupMenu);
    }

    /**
     * Unregisters listeners.
     */
    protected void uninstallListeners() {
        if (popupMenuListener != null) {
            popupMenu.removePopupMenuListener(popupMenuListener);
        }
        if (menuKeyListener != null) {
            popupMenu.removeMenuKeyListener(menuKeyListener);
        }
    }

    /**
     * Unregisters keyboard actions.
     */
    protected void uninstallKeyboardActions() {
        SwingUtilities.replaceUIActionMap(popupMenu, null);
        SwingUtilities.replaceUIInputMap(popupMenu,
                                  JComponent.WHEN_IN_FOCUSED_WINDOW, null);
    }

    static MenuElement getFirstPopup() {
        MenuSelectionManager msm = MenuSelectionManager.defaultManager();
        MenuElement[] p = msm.getSelectedPath();
        MenuElement me = null;

        for(int i = 0 ; me == null && i < p.length ; i++) {
            if (p[i] instanceof JPopupMenu)
                me = p[i];
        }

        return me;
    }

    static JPopupMenu getLastPopup() {
        MenuSelectionManager msm = MenuSelectionManager.defaultManager();
        MenuElement[] p = msm.getSelectedPath();
        JPopupMenu popup = null;

        for(int i = p.length - 1; popup == null && i >= 0; i--) {
            if (p[i] instanceof JPopupMenu)
                popup = (JPopupMenu)p[i];
        }
        return popup;
    }

    static List<JPopupMenu> getPopups() {
        MenuSelectionManager msm = MenuSelectionManager.defaultManager();
        MenuElement[] p = msm.getSelectedPath();

        List<JPopupMenu> list = new ArrayList<JPopupMenu>(p.length);
        for (MenuElement element : p) {
            if (element instanceof JPopupMenu) {
                list.add((JPopupMenu) element);
            }
        }
        return list;
    }

    public boolean isPopupTrigger(MouseEvent e) {
        return ((e.getID()==MouseEvent.MOUSE_RELEASED)
                && ((e.getModifiers() & MouseEvent.BUTTON3_MASK)!=0));
    }

    private static boolean checkInvokerEqual(MenuElement present, MenuElement last) {
        Component invokerPresent = present.getComponent();
        Component invokerLast = last.getComponent();

        if (invokerPresent instanceof JPopupMenu) {
            invokerPresent = ((JPopupMenu)invokerPresent).getInvoker();
    }
        if (invokerLast instanceof JPopupMenu) {
            invokerLast = ((JPopupMenu)invokerLast).getInvoker();
        }
        return (invokerPresent == invokerLast);
    }


    /**
     * This Listener fires the Action that provides the correct auditory
     * feedback.
     *
     * @since 1.4
     */
    private class BasicPopupMenuListener implements PopupMenuListener {
        public void popupMenuCanceled(PopupMenuEvent e) {
        }

        public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
        }

        public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
            BasicLookAndFeel.playSound((JPopupMenu)e.getSource(),
                                       "PopupMenu.popupSound");
        }
    }

    /**
     * Handles mnemonic for children JMenuItems.
     * @since 1.5
     */
    private class BasicMenuKeyListener implements MenuKeyListener {
        MenuElement menuToOpen = null;

        public void menuKeyTyped(MenuKeyEvent e) {
            if (menuToOpen != null) {
                // we have a submenu to open
                JPopupMenu subpopup = ((JMenu)menuToOpen).getPopupMenu();
                MenuElement subitem = findEnabledChild(
                        subpopup.getSubElements(), -1, true);

                ArrayList<MenuElement> lst = new ArrayList<MenuElement>(Arrays.asList(e.getPath()));
                lst.add(menuToOpen);
                lst.add(subpopup);
                if (subitem != null) {
                    lst.add(subitem);
                }
                MenuElement newPath[] = new MenuElement[0];
                newPath = lst.toArray(newPath);
                MenuSelectionManager.defaultManager().setSelectedPath(newPath);
                e.consume();
            }
            menuToOpen = null;
        }

        public void menuKeyPressed(MenuKeyEvent e) {
            char keyChar = e.getKeyChar();

            // Handle the case for Escape or Enter...
            if (!Character.isLetterOrDigit(keyChar)) {
                return;
            }

            MenuSelectionManager manager = e.getMenuSelectionManager();
            MenuElement path[] = e.getPath();
            MenuElement items[] = popupMenu.getSubElements();
            int currentIndex = -1;
            int matches = 0;
            int firstMatch = -1;
            int indexes[] = null;

            for (int j = 0; j < items.length; j++) {
                if (! (items[j] instanceof JMenuItem)) {
                    continue;
                }
                JMenuItem item = (JMenuItem)items[j];
                int mnemonic = item.getMnemonic();
                if (item.isEnabled() &&
                    item.isVisible() && lower(keyChar) == lower(mnemonic)) {
                    if (matches == 0) {
                        firstMatch = j;
                        matches++;
                    } else {
                        if (indexes == null) {
                            indexes = new int[items.length];
                            indexes[0] = firstMatch;
                        }
                        indexes[matches++] = j;
                    }
                }
                if (item.isArmed() || item.isSelected()) {
                    currentIndex = matches - 1;
                }
            }

            if (matches == 0) {
                // no op
            } else if (matches == 1) {
                // Invoke the menu action
                JMenuItem item = (JMenuItem)items[firstMatch];
                if (item instanceof JMenu) {
                    // submenus are handled in menuKeyTyped
                    menuToOpen = item;
                } else if (item.isEnabled()) {
                    // we have a menu item
                    manager.clearSelectedPath();
                    item.doClick();
                }
                e.consume();
            } else {
                // Select the menu item with the matching mnemonic. If
                // the same mnemonic has been invoked then select the next
                // menu item in the cycle.
                MenuElement newItem;

                newItem = items[indexes[(currentIndex + 1) % matches]];

                MenuElement newPath[] = new MenuElement[path.length+1];
                System.arraycopy(path, 0, newPath, 0, path.length);
                newPath[path.length] = newItem;
                manager.setSelectedPath(newPath);
                e.consume();
            }
        }

        public void menuKeyReleased(MenuKeyEvent e) {
        }

        private char lower(char keyChar) {
            return Character.toLowerCase(keyChar);
        }

        private char lower(int mnemonic) {
            return Character.toLowerCase((char) mnemonic);
        }
    }

    private static class Actions extends UIAction {
        // Types of actions
        private static final String CANCEL = "cancel";
        private static final String SELECT_NEXT = "selectNext";
        private static final String SELECT_PREVIOUS = "selectPrevious";
        private static final String SELECT_PARENT = "selectParent";
        private static final String SELECT_CHILD = "selectChild";
        private static final String RETURN = "return";

        // Used for next/previous actions
        private static final boolean FORWARD = true;
        private static final boolean BACKWARD = false;

        // Used for parent/child actions
        private static final boolean PARENT = false;
        private static final boolean CHILD = true;


        Actions(String key) {
            super(key);
        }

        public void actionPerformed(ActionEvent e) {
            String key = getName();
            if (key == CANCEL) {
                cancel();
            }
            else if (key == SELECT_NEXT) {
                selectItem(FORWARD);
            }
            else if (key == SELECT_PREVIOUS) {
                selectItem(BACKWARD);
            }
            else if (key == SELECT_PARENT) {
                selectParentChild(PARENT);
            }
            else if (key == SELECT_CHILD) {
                selectParentChild(CHILD);
            }
            else if (key == RETURN) {
                doReturn();
            }
        }

        private void doReturn() {
            KeyboardFocusManager fmgr =
                KeyboardFocusManager.getCurrentKeyboardFocusManager();
            Component focusOwner = fmgr.getFocusOwner();
            if(focusOwner != null && !(focusOwner instanceof JRootPane)) {
                return;
            }

            MenuSelectionManager msm = MenuSelectionManager.defaultManager();
            MenuElement path[] = msm.getSelectedPath();
            MenuElement lastElement;
            if(path.length > 0) {
                lastElement = path[path.length-1];
                if(lastElement instanceof JMenu) {
                    MenuElement newPath[] = new MenuElement[path.length+1];
                    System.arraycopy(path,0,newPath,0,path.length);
                    newPath[path.length] = ((JMenu)lastElement).getPopupMenu();
                    msm.setSelectedPath(newPath);
                } else if(lastElement instanceof JMenuItem) {
                    JMenuItem mi = (JMenuItem)lastElement;

                    if (mi.getUI() instanceof BasicMenuItemUI) {
                        ((BasicMenuItemUI)mi.getUI()).doClick(msm);
                    }
                    else {
                        msm.clearSelectedPath();
                        mi.doClick(0);
                    }
                }
            }
        }
        private void selectParentChild(boolean direction) {
            MenuSelectionManager msm = MenuSelectionManager.defaultManager();
            MenuElement path[] = msm.getSelectedPath();
            int len = path.length;

            if (direction == PARENT) {
                // selecting parent
                int popupIndex = len-1;

                if (len > 2 &&
                    // check if we have an open submenu. A submenu item may or
                    // may not be selected, so submenu popup can be either the
                    // last or next to the last item.
                    (path[popupIndex] instanceof JPopupMenu ||
                     path[--popupIndex] instanceof JPopupMenu) &&
                    !((JMenu)path[popupIndex-1]).isTopLevelMenu()) {

                    // we have a submenu, just close it
                    MenuElement newPath[] = new MenuElement[popupIndex];
                    System.arraycopy(path, 0, newPath, 0, popupIndex);
                    msm.setSelectedPath(newPath);
                    return;
                }
            } else {
                // selecting child
                if (len > 0 && path[len-1] instanceof JMenu &&
                    !((JMenu)path[len-1]).isTopLevelMenu()) {

                    // we have a submenu, open it
                    JMenu menu = (JMenu)path[len-1];
                    JPopupMenu popup = menu.getPopupMenu();
                    MenuElement[] subs = popup.getSubElements();
                    MenuElement item = findEnabledChild(subs, -1, true);
                    MenuElement[] newPath;

                    if (item == null) {
                        newPath = new MenuElement[len+1];
                    } else {
                        newPath = new MenuElement[len+2];
                        newPath[len+1] = item;
                    }
                    System.arraycopy(path, 0, newPath, 0, len);
                    newPath[len] = popup;
                    msm.setSelectedPath(newPath);
                    return;
                }
            }

            // check if we have a toplevel menu selected.
            // If this is the case, we select another toplevel menu
            if (len > 1 && path[0] instanceof JMenuBar) {
                MenuElement currentMenu = path[1];
                MenuElement nextMenu = findEnabledChild(
                    path[0].getSubElements(), currentMenu, direction);

                if (nextMenu != null && nextMenu != currentMenu) {
                    MenuElement newSelection[];
                    if (len == 2) {
                        // menu is selected but its popup not shown
                        newSelection = new MenuElement[2];
                        newSelection[0] = path[0];
                        newSelection[1] = nextMenu;
                    } else {
                        // menu is selected and its popup is shown
                        newSelection = new MenuElement[3];
                        newSelection[0] = path[0];
                        newSelection[1] = nextMenu;
                        newSelection[2] = ((JMenu)nextMenu).getPopupMenu();
                    }
                    msm.setSelectedPath(newSelection);
                }
            }
        }

        private void selectItem(boolean direction) {
            MenuSelectionManager msm = MenuSelectionManager.defaultManager();
            MenuElement path[] = msm.getSelectedPath();
            if (path.length == 0) {
                return;
            }
            int len = path.length;
            if (len == 1 && path[0] instanceof JPopupMenu) {

                JPopupMenu popup = (JPopupMenu) path[0];
                MenuElement[] newPath = new MenuElement[2];
                newPath[0] = popup;
                newPath[1] = findEnabledChild(popup.getSubElements(), -1, direction);
                msm.setSelectedPath(newPath);
            } else if (len == 2 &&
                    path[0] instanceof JMenuBar && path[1] instanceof JMenu) {

                // a toplevel menu is selected, but its popup not shown.
                // Show the popup and select the first item
                JPopupMenu popup = ((JMenu)path[1]).getPopupMenu();
                MenuElement next =
                    findEnabledChild(popup.getSubElements(), -1, FORWARD);
                MenuElement[] newPath;

                if (next != null) {
                    // an enabled item found -- include it in newPath
                    newPath = new MenuElement[4];
                    newPath[3] = next;
                } else {
                    // menu has no enabled items -- still must show the popup
                    newPath = new MenuElement[3];
                }
                System.arraycopy(path, 0, newPath, 0, 2);
                newPath[2] = popup;
                msm.setSelectedPath(newPath);

            } else if (path[len-1] instanceof JPopupMenu &&
                       path[len-2] instanceof JMenu) {

                // a menu (not necessarily toplevel) is open and its popup
                // shown. Select the appropriate menu item
                JMenu menu = (JMenu)path[len-2];
                JPopupMenu popup = menu.getPopupMenu();
                MenuElement next =
                    findEnabledChild(popup.getSubElements(), -1, direction);

                if (next != null) {
                    MenuElement[] newPath = new MenuElement[len+1];
                    System.arraycopy(path, 0, newPath, 0, len);
                    newPath[len] = next;
                    msm.setSelectedPath(newPath);
                } else {
                    // all items in the popup are disabled.
                    // We're going to find the parent popup menu and select
                    // its next item. If there's no parent popup menu (i.e.
                    // current menu is toplevel), do nothing
                    if (len > 2 && path[len-3] instanceof JPopupMenu) {
                        popup = ((JPopupMenu)path[len-3]);
                        next = findEnabledChild(popup.getSubElements(),
                                                menu, direction);

                        if (next != null && next != menu) {
                            MenuElement[] newPath = new MenuElement[len-1];
                            System.arraycopy(path, 0, newPath, 0, len-2);
                            newPath[len-2] = next;
                            msm.setSelectedPath(newPath);
                        }
                    }
                }

            } else {
                // just select the next item, no path expansion needed
                MenuElement subs[] = path[len-2].getSubElements();
                MenuElement nextChild =
                    findEnabledChild(subs, path[len-1], direction);
                if (nextChild == null) {
                    nextChild = findEnabledChild(subs, -1, direction);
                }
                if (nextChild != null) {
                    path[len-1] = nextChild;
                    msm.setSelectedPath(path);
                }
            }
        }

        private void cancel() {
            // 4234793: This action should call JPopupMenu.firePopupMenuCanceled but it's
            // a protected method. The real solution could be to make
            // firePopupMenuCanceled public and call it directly.
            JPopupMenu lastPopup = getLastPopup();
            if (lastPopup != null) {
                lastPopup.putClientProperty("JPopupMenu.firePopupMenuCanceled", Boolean.TRUE);
            }
            String mode = UIManager.getString("Menu.cancelMode");
            if ("hideMenuTree".equals(mode)) {
                MenuSelectionManager.defaultManager().clearSelectedPath();
            } else {
                shortenSelectedPath();
            }
        }

        private void shortenSelectedPath() {
            MenuElement path[] = MenuSelectionManager.defaultManager().getSelectedPath();
            if (path.length <= 2) {
                MenuSelectionManager.defaultManager().clearSelectedPath();
                return;
            }
            // unselect MenuItem and its Popup by default
            int value = 2;
            MenuElement lastElement = path[path.length - 1];
            JPopupMenu lastPopup = getLastPopup();
            if (lastElement == lastPopup) {
                MenuElement previousElement = path[path.length - 2];
                if (previousElement instanceof JMenu) {
                    JMenu lastMenu = (JMenu) previousElement;
                    if (lastMenu.isEnabled() && lastPopup.getComponentCount() > 0) {
                        // unselect the last visible popup only
                        value = 1;
                    } else {
                        // unselect invisible popup and two visible elements
                        value = 3;
                    }
                }
            }
            if (path.length - value <= 2
                    && !UIManager.getBoolean("Menu.preserveTopLevelSelection")) {
                // clear selection for the topLevelMenu
                value = path.length;
            }
            MenuElement newPath[] = new MenuElement[path.length - value];
            System.arraycopy(path, 0, newPath, 0, path.length - value);
            MenuSelectionManager.defaultManager().setSelectedPath(newPath);
        }
    }

    private static MenuElement nextEnabledChild(MenuElement e[],
                                                int fromIndex, int toIndex) {
        for (int i=fromIndex; i<=toIndex; i++) {
            if (e[i] != null) {
                Component comp = e[i].getComponent();
                if ( comp != null
                        && (comp.isEnabled() || UIManager.getBoolean("MenuItem.disabledAreNavigable"))
                        && comp.isVisible()) {
                    return e[i];
                }
            }
        }
        return null;
    }

    private static MenuElement previousEnabledChild(MenuElement e[],
                                                int fromIndex, int toIndex) {
        for (int i=fromIndex; i>=toIndex; i--) {
            if (e[i] != null) {
                Component comp = e[i].getComponent();
                if ( comp != null
                        && (comp.isEnabled() || UIManager.getBoolean("MenuItem.disabledAreNavigable"))
                        && comp.isVisible()) {
                    return e[i];
                }
            }
        }
        return null;
    }

    static MenuElement findEnabledChild(MenuElement e[], int fromIndex,
                                                boolean forward) {
        MenuElement result;
        if (forward) {
            result = nextEnabledChild(e, fromIndex+1, e.length-1);
            if (result == null) result = nextEnabledChild(e, 0, fromIndex-1);
        } else {
            result = previousEnabledChild(e, fromIndex-1, 0);
            if (result == null) result = previousEnabledChild(e, e.length-1,
                                                              fromIndex+1);
        }
        return result;
    }

    static MenuElement findEnabledChild(MenuElement e[],
                                   MenuElement elem, boolean forward) {
        for (int i=0; i<e.length; i++) {
            if (e[i] == elem) {
                return findEnabledChild(e, i, forward);
            }
        }
        return null;
    }

    static class MouseGrabber implements ChangeListener,
        AWTEventListener, ComponentListener, WindowListener {

        Window grabbedWindow;
        MenuElement[] lastPathSelected;

        public MouseGrabber() {
            MenuSelectionManager msm = MenuSelectionManager.defaultManager();
            msm.addChangeListener(this);
            this.lastPathSelected = msm.getSelectedPath();
            if(this.lastPathSelected.length != 0) {
                grabWindow(this.lastPathSelected);
            }
        }

        void uninstall() {
            synchronized (MOUSE_GRABBER_KEY) {
                MenuSelectionManager.defaultManager().removeChangeListener(this);
                ungrabWindow();
                AppContext.getAppContext().remove(MOUSE_GRABBER_KEY);
            }
        }

        void grabWindow(MenuElement[] newPath) {
            // A grab needs to be added
            final Toolkit tk = Toolkit.getDefaultToolkit();
            java.security.AccessController.doPrivileged(
                new java.security.PrivilegedAction<Object>() {
                    public Object run() {
                        tk.addAWTEventListener(MouseGrabber.this,
                                AWTEvent.MOUSE_EVENT_MASK |
                                AWTEvent.MOUSE_MOTION_EVENT_MASK |
                                AWTEvent.MOUSE_WHEEL_EVENT_MASK |
                                AWTEvent.WINDOW_EVENT_MASK | sun.awt.SunToolkit.GRAB_EVENT_MASK);
                        return null;
                    }
                }
            );

            Component invoker = newPath[0].getComponent();
            if (invoker instanceof JPopupMenu) {
                invoker = ((JPopupMenu)invoker).getInvoker();
            }
            grabbedWindow = (invoker == null)
                    ? null
                    : ((invoker instanceof Window)
                            ? (Window) invoker
                            : SwingUtilities.getWindowAncestor(invoker));
            if(grabbedWindow != null) {
                if(tk instanceof sun.awt.SunToolkit) {
                    ((sun.awt.SunToolkit)tk).grab(grabbedWindow);
                } else {
                    grabbedWindow.addComponentListener(this);
                    grabbedWindow.addWindowListener(this);
                }
            }
        }

        void ungrabWindow() {
            final Toolkit tk = Toolkit.getDefaultToolkit();
            // The grab should be removed
             java.security.AccessController.doPrivileged(
                new java.security.PrivilegedAction<Object>() {
                    public Object run() {
                        tk.removeAWTEventListener(MouseGrabber.this);
                        return null;
                    }
                }
            );
            realUngrabWindow();
        }

        void realUngrabWindow() {
            Toolkit tk = Toolkit.getDefaultToolkit();
            if(grabbedWindow != null) {
                if(tk instanceof sun.awt.SunToolkit) {
                    ((sun.awt.SunToolkit)tk).ungrab(grabbedWindow);
                } else {
                    grabbedWindow.removeComponentListener(this);
                    grabbedWindow.removeWindowListener(this);
                }
                grabbedWindow = null;
            }
        }

        public void stateChanged(ChangeEvent e) {
            MenuSelectionManager msm = MenuSelectionManager.defaultManager();
            MenuElement[] p = msm.getSelectedPath();

            if (lastPathSelected.length == 0 && p.length != 0) {
                grabWindow(p);
            }

            if (lastPathSelected.length != 0 && p.length == 0) {
                ungrabWindow();
            }

            lastPathSelected = p;
        }

        public void eventDispatched(AWTEvent ev) {
            if(ev instanceof sun.awt.UngrabEvent) {
                // Popup should be canceled in case of ungrab event
                cancelPopupMenu( );
                return;
            }
            if (!(ev instanceof MouseEvent)) {
                // We are interested in MouseEvents only
                return;
            }
            MouseEvent me = (MouseEvent) ev;
            Component src = me.getComponent();
            switch (me.getID()) {
            case MouseEvent.MOUSE_PRESSED:
                if (isInPopup(src) ||
                    (src instanceof JMenu && ((JMenu)src).isSelected())) {
                    return;
                }
                if (!(src instanceof JComponent) ||
                   ! (((JComponent)src).getClientProperty("doNotCancelPopup")
                         == BasicComboBoxUI.HIDE_POPUP_KEY)) {
                    // Cancel popup only if this property was not set.
                    // If this property is set to TRUE component wants
                    // to deal with this event by himself.
                    cancelPopupMenu();
                    // Ask UIManager about should we consume event that closes
                    // popup. This made to match native apps behaviour.
                    boolean consumeEvent =
                        UIManager.getBoolean("PopupMenu.consumeEventOnClose");
                    // Consume the event so that normal processing stops.
                    if(consumeEvent && !(src instanceof MenuElement)) {
                        me.consume();
                    }
                }
                break;

            case MouseEvent.MOUSE_RELEASED:
                if(!(src instanceof MenuElement)) {
                    // Do not forward event to MSM, let component handle it
                    if (isInPopup(src)) {
                        break;
                    }
                }
                if(src instanceof JMenu || !(src instanceof JMenuItem)) {
                    MenuSelectionManager.defaultManager().
                        processMouseEvent(me);
                }
                break;
            case MouseEvent.MOUSE_DRAGGED:
                if(!(src instanceof MenuElement)) {
                    // For the MOUSE_DRAGGED event the src is
                    // the Component in which mouse button was pressed.
                    // If the src is in popupMenu,
                    // do not forward event to MSM, let component handle it.
                    if (isInPopup(src)) {
                        break;
                    }
                }
                MenuSelectionManager.defaultManager().
                    processMouseEvent(me);
                break;
            case MouseEvent.MOUSE_WHEEL:
                if (isInPopup(src)
                    || ((src instanceof JComboBox) && ((JComboBox) src).isPopupVisible())) {

                    return;
                }
                cancelPopupMenu();
                break;
            }
        }

        @SuppressWarnings("deprecation")
        boolean isInPopup(Component src) {
            for (Component c=src; c!=null; c=c.getParent()) {
                if (c instanceof Applet || c instanceof Window) {
                    break;
                } else if (c instanceof JPopupMenu) {
                    return true;
                }
            }
            return false;
        }

        void cancelPopupMenu() {
            // We should ungrab window if a user code throws
            // an unexpected runtime exception. See 6495920.
            try {
                // 4234793: This action should call firePopupMenuCanceled but it's
                // a protected method. The real solution could be to make
                // firePopupMenuCanceled public and call it directly.
                List<JPopupMenu> popups = getPopups();
                for (JPopupMenu popup : popups) {
                    popup.putClientProperty("JPopupMenu.firePopupMenuCanceled", Boolean.TRUE);
                }
                MenuSelectionManager.defaultManager().clearSelectedPath();
            } catch (RuntimeException ex) {
                realUngrabWindow();
                throw ex;
            } catch (Error err) {
                realUngrabWindow();
                throw err;
            }
        }

        public void componentResized(ComponentEvent e) {
            cancelPopupMenu();
        }
        public void componentMoved(ComponentEvent e) {
            cancelPopupMenu();
        }
        public void componentShown(ComponentEvent e) {
            cancelPopupMenu();
        }
        public void componentHidden(ComponentEvent e) {
            cancelPopupMenu();
        }
        public void windowClosing(WindowEvent e) {
            cancelPopupMenu();
        }
        public void windowClosed(WindowEvent e) {
            cancelPopupMenu();
        }
        public void windowIconified(WindowEvent e) {
            cancelPopupMenu();
        }
        public void windowDeactivated(WindowEvent e) {
            cancelPopupMenu();
        }
        public void windowOpened(WindowEvent e) {}
        public void windowDeiconified(WindowEvent e) {}
        public void windowActivated(WindowEvent e) {}
    }

    /**
     * This helper is added to MenuSelectionManager as a ChangeListener to
     * listen to menu selection changes. When a menu is activated, it passes
     * focus to its parent JRootPane, and installs an ActionMap/InputMap pair
     * on that JRootPane. Those maps are necessary in order for menu
     * navigation to work. When menu is being deactivated, it restores focus
     * to the component that has had it before menu activation, and uninstalls
     * the maps.
     * This helper is also installed as a KeyListener on root pane when menu
     * is active. It forwards key events to MenuSelectionManager for mnemonic
     * keys handling.
     */
    static class MenuKeyboardHelper
        implements ChangeListener, KeyListener {

        private Component lastFocused = null;
        private MenuElement[] lastPathSelected = new MenuElement[0];
        private JPopupMenu lastPopup;

        private JRootPane invokerRootPane;
        private ActionMap menuActionMap = getActionMap();
        private InputMap menuInputMap;
        private boolean focusTraversalKeysEnabled;

        /*
         * Fix for 4213634
         * If this is false, KEY_TYPED and KEY_RELEASED events are NOT
         * processed. This is needed to avoid activating a menuitem when
         * the menu and menuitem share the same mnemonic.
         */
        private boolean receivedKeyPressed = false;

        void removeItems() {
            if (lastFocused != null) {
                if(!lastFocused.requestFocusInWindow()) {
                    // Workarounr for 4810575.
                    // If lastFocused is not in currently focused window
                    // requestFocusInWindow will fail. In this case we must
                    // request focus by requestFocus() if it was not
                    // transferred from our popup.
                    Window cfw = KeyboardFocusManager
                                 .getCurrentKeyboardFocusManager()
                                  .getFocusedWindow();
                    if(cfw != null &&
                       "###focusableSwingPopup###".equals(cfw.getName())) {
                        lastFocused.requestFocus();
                    }

                }
                lastFocused = null;
            }
            if (invokerRootPane != null) {
                invokerRootPane.removeKeyListener(this);
                invokerRootPane.setFocusTraversalKeysEnabled(focusTraversalKeysEnabled);
                removeUIInputMap(invokerRootPane, menuInputMap);
                removeUIActionMap(invokerRootPane, menuActionMap);
                invokerRootPane = null;
            }
            receivedKeyPressed = false;
        }

        private FocusListener rootPaneFocusListener = new FocusAdapter() {
                public void focusGained(FocusEvent ev) {
                    Component opposite = ev.getOppositeComponent();
                    if (opposite != null) {
                        lastFocused = opposite;
                    }
                    ev.getComponent().removeFocusListener(this);
                }
            };

        /**
         * Return the last JPopupMenu in <code>path</code>,
         * or <code>null</code> if none found
         */
        JPopupMenu getActivePopup(MenuElement[] path) {
            for (int i=path.length-1; i>=0; i--) {
                MenuElement elem = path[i];
                if (elem instanceof JPopupMenu) {
                    return (JPopupMenu)elem;
                }
            }
            return null;
        }

        void addUIInputMap(JComponent c, InputMap map) {
            InputMap lastNonUI = null;
            InputMap parent = c.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);

            while (parent != null && !(parent instanceof UIResource)) {
                lastNonUI = parent;
                parent = parent.getParent();
            }

            if (lastNonUI == null) {
                c.setInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW, map);
            } else {
                lastNonUI.setParent(map);
            }
            map.setParent(parent);
        }

        void addUIActionMap(JComponent c, ActionMap map) {
            ActionMap lastNonUI = null;
            ActionMap parent = c.getActionMap();

            while (parent != null && !(parent instanceof UIResource)) {
                lastNonUI = parent;
                parent = parent.getParent();
            }

            if (lastNonUI == null) {
                c.setActionMap(map);
            } else {
                lastNonUI.setParent(map);
            }
            map.setParent(parent);
        }

        void removeUIInputMap(JComponent c, InputMap map) {
            InputMap im = null;
            InputMap parent = c.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);

            while (parent != null) {
                if (parent == map) {
                    if (im == null) {
                        c.setInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW,
                                      map.getParent());
                    } else {
                        im.setParent(map.getParent());
                    }
                    break;
                }
                im = parent;
                parent = parent.getParent();
            }
        }

        void removeUIActionMap(JComponent c, ActionMap map) {
            ActionMap im = null;
            ActionMap parent = c.getActionMap();

            while (parent != null) {
                if (parent == map) {
                    if (im == null) {
                        c.setActionMap(map.getParent());
                    } else {
                        im.setParent(map.getParent());
                    }
                    break;
                }
                im = parent;
                parent = parent.getParent();
            }
        }

        @SuppressWarnings("deprecation")
        public void stateChanged(ChangeEvent ev) {
            if (!(UIManager.getLookAndFeel() instanceof BasicLookAndFeel)) {
                uninstall();
                return;
            }
            MenuSelectionManager msm = (MenuSelectionManager)ev.getSource();
            MenuElement[] p = msm.getSelectedPath();
            JPopupMenu popup = getActivePopup(p);
            if (popup != null && !popup.isFocusable()) {
                // Do nothing for non-focusable popups
                return;
            }

            if (lastPathSelected.length != 0 && p.length != 0 ) {
                if (!checkInvokerEqual(p[0],lastPathSelected[0])) {
                    removeItems();
                    lastPathSelected = new MenuElement[0];
                }
            }

            if (lastPathSelected.length == 0 && p.length > 0) {
                // menu posted
                JComponent invoker;

                if (popup == null) {
                    if (p.length == 2 && p[0] instanceof JMenuBar &&
                        p[1] instanceof JMenu) {
                        // a menu has been selected but not open
                        invoker = (JComponent)p[1];
                        popup = ((JMenu)invoker).getPopupMenu();
                    } else {
                        return;
                    }
                } else {
                    Component c = popup.getInvoker();
                    if(c instanceof JFrame) {
                        invoker = ((JFrame)c).getRootPane();
                    } else if(c instanceof JDialog) {
                        invoker = ((JDialog)c).getRootPane();
                    } else if(c instanceof JApplet) {
                        invoker = ((JApplet)c).getRootPane();
                    } else {
                        while (!(c instanceof JComponent)) {
                            if (c == null) {
                                return;
                            }
                            c = c.getParent();
                        }
                        invoker = (JComponent)c;
                    }
                }

                // remember current focus owner
                lastFocused = KeyboardFocusManager.
                    getCurrentKeyboardFocusManager().getFocusOwner();

                // request focus on root pane and install keybindings
                // used for menu navigation
                invokerRootPane = SwingUtilities.getRootPane(invoker);
                if (invokerRootPane != null) {
                    invokerRootPane.addFocusListener(rootPaneFocusListener);
                    invokerRootPane.requestFocus(true);
                    invokerRootPane.addKeyListener(this);
                    focusTraversalKeysEnabled = invokerRootPane.
                                      getFocusTraversalKeysEnabled();
                    invokerRootPane.setFocusTraversalKeysEnabled(false);

                    menuInputMap = getInputMap(popup, invokerRootPane);
                    addUIInputMap(invokerRootPane, menuInputMap);
                    addUIActionMap(invokerRootPane, menuActionMap);
                }
            } else if (lastPathSelected.length != 0 && p.length == 0) {
                // menu hidden -- return focus to where it had been before
                // and uninstall menu keybindings
                   removeItems();
            } else {
                if (popup != lastPopup) {
                    receivedKeyPressed = false;
                }
            }

            // Remember the last path selected
            lastPathSelected = p;
            lastPopup = popup;
        }

        public void keyPressed(KeyEvent ev) {
            receivedKeyPressed = true;
            MenuSelectionManager.defaultManager().processKeyEvent(ev);
        }

        public void keyReleased(KeyEvent ev) {
            if (receivedKeyPressed) {
                receivedKeyPressed = false;
                MenuSelectionManager.defaultManager().processKeyEvent(ev);
            }
        }

        public void keyTyped(KeyEvent ev) {
            if (receivedKeyPressed) {
                MenuSelectionManager.defaultManager().processKeyEvent(ev);
            }
        }

        void uninstall() {
            synchronized (MENU_KEYBOARD_HELPER_KEY) {
                MenuSelectionManager.defaultManager().removeChangeListener(this);
                AppContext.getAppContext().remove(MENU_KEYBOARD_HELPER_KEY);
            }
        }
    }
}