/*

 * Copyright 2000-2002 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.swing;

import java.awt.FocusTraversalPolicy;

import java.awt.Component;

import java.awt.Container;

import java.awt.Window;

import java.util.HashMap;

import java.util.HashSet;

import java.io.*;

/**

 * A FocusTraversalPolicy which provides support for legacy applications which

 * handle focus traversal via JComponent.setNextFocusableComponent or by

 * installing a custom DefaultFocusManager. If a specific traversal has not

 * been hard coded, then that traversal is provided either by the custom

 * DefaultFocusManager, or by a wrapped FocusTraversalPolicy instance.

 *

 * @author David Mendenhall

 */

final class LegacyGlueFocusTraversalPolicy extends FocusTraversalPolicy

    implements Serializable

{

    private transient FocusTraversalPolicy delegatePolicy;

    private transient DefaultFocusManager delegateManager;

    private HashMap forwardMap = new HashMap(),

        backwardMap = new HashMap();

    LegacyGlueFocusTraversalPolicy(FocusTraversalPolicy delegatePolicy) {

        this.delegatePolicy = delegatePolicy;

    }

    LegacyGlueFocusTraversalPolicy(DefaultFocusManager delegateManager) {

        this.delegateManager = delegateManager;

    }

    void setNextFocusableComponent(Component left, Component right) {

        forwardMap.put(left, right);

        backwardMap.put(right, left);

    }

    void unsetNextFocusableComponent(Component left, Component right) {

        forwardMap.remove(left);

        backwardMap.remove(right);

    }

    public Component getComponentAfter(Container focusCycleRoot,

                                       Component aComponent) {

        Component hardCoded = aComponent, prevHardCoded;

        HashSet sanity = new HashSet();

        do {

            prevHardCoded = hardCoded;

            hardCoded = (Component)forwardMap.get(hardCoded);

            if (hardCoded == null) {

                if (delegatePolicy != null &&

                    prevHardCoded.isFocusCycleRoot(focusCycleRoot)) {

                    return delegatePolicy.getComponentAfter(focusCycleRoot,

                                                            prevHardCoded);

                } else if (delegateManager != null) {

                    return delegateManager.

                        getComponentAfter(focusCycleRoot, aComponent);

                } else {

                    return null;

                }

            }

            if (sanity.contains(hardCoded)) {

                // cycle detected; bail

                return null;

            }

            sanity.add(hardCoded);

        } while (!accept(hardCoded));

        return hardCoded;

    }

    public Component getComponentBefore(Container focusCycleRoot,

                                        Component aComponent) {

        Component hardCoded = aComponent, prevHardCoded;

        HashSet sanity = new HashSet();

        do {

            prevHardCoded = hardCoded;

            hardCoded = (Component)backwardMap.get(hardCoded);

            if (hardCoded == null) {

                if (delegatePolicy != null &&

                    prevHardCoded.isFocusCycleRoot(focusCycleRoot)) {

                    return delegatePolicy.getComponentBefore(focusCycleRoot,

                                                       prevHardCoded);

                } else if (delegateManager != null) {

                    return delegateManager.

                        getComponentBefore(focusCycleRoot, aComponent);

                } else {

                    return null;

                }

            }

            if (sanity.contains(hardCoded)) {

                // cycle detected; bail

                return null;

            }

            sanity.add(hardCoded);

        } while (!accept(hardCoded));

        return hardCoded;

    }

    public Component getFirstComponent(Container focusCycleRoot) {

        if (delegatePolicy != null) {

            return delegatePolicy.getFirstComponent(focusCycleRoot);

        } else if (delegateManager != null) {

            return delegateManager.getFirstComponent(focusCycleRoot);

        } else {

            return null;

        }

    }

    public Component getLastComponent(Container focusCycleRoot) {

        if (delegatePolicy != null) {

            return delegatePolicy.getLastComponent(focusCycleRoot);

        } else if (delegateManager != null) {

            return delegateManager.getLastComponent(focusCycleRoot);

        } else {

            return null;

        }

    }

    public Component getDefaultComponent(Container focusCycleRoot) {

        if (delegatePolicy != null) {

            return delegatePolicy.getDefaultComponent(focusCycleRoot);

        } else {

            return getFirstComponent(focusCycleRoot);

        }

    }

    private boolean accept(Component aComponent) {

        if (!(aComponent.isVisible() && aComponent.isDisplayable() &&

              aComponent.isFocusable() && aComponent.isEnabled())) {

            return false;

        }

        // Verify that the Component is recursively enabled. Disabling a

        // heavyweight Container disables its children, whereas disabling

        // a lightweight Container does not.

        if (!(aComponent instanceof Window)) {

            for (Container enableTest = aComponent.getParent();

                 enableTest != null;

                 enableTest = enableTest.getParent())

            {

                if (!(enableTest.isEnabled() || enableTest.isLightweight())) {

                    return false;

                }

                if (enableTest instanceof Window) {

                    break;

                }

            }

        }

        return true;

    }

    private void writeObject(ObjectOutputStream out) throws IOException {

        out.defaultWriteObject();

        if (delegatePolicy instanceof Serializable) {

            out.writeObject(delegatePolicy);

        } else {

            out.writeObject(null);

        }

        if (delegateManager instanceof Serializable) {

            out.writeObject(delegateManager);

        } else {

            out.writeObject(null);

        }

    }

    private void readObject(ObjectInputStream in)

        throws IOException, ClassNotFoundException

    {

        in.defaultReadObject();

        delegatePolicy = (FocusTraversalPolicy)in.readObject();

        delegateManager = (DefaultFocusManager)in.readObject();

    }

}