/*

 * Copyright (c) 1996, 2008, 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 java.beans;

import java.io.Serializable;

import java.io.ObjectStreamField;

import java.io.ObjectOutputStream;

import java.io.ObjectInputStream;

import java.io.IOException;

import java.util.Hashtable;

import java.util.Map.Entry;

/**

 * This is a utility class that can be used by beans that support constrained

 * properties.  It manages a list of listeners and dispatches

 * {@link PropertyChangeEvent}s to them.  You can use an instance of this class

 * as a member field of your bean and delegate these types of work to it.

 * The {@link VetoableChangeListener} can be registered for all properties

 * or for a property specified by name.

 * <p>

 * Here is an example of {@code VetoableChangeSupport} usage that follows

 * the rules and recommendations laid out in the JavaBeans™ specification:

 * <pre>

 * public class MyBean {

 *     private final VetoableChangeSupport vcs = new VetoableChangeSupport(this);

 *

 *     public void addVetoableChangeListener(VetoableChangeListener listener) {

 *         this.vcs.addVetoableChangeListener(listener);

 *     }

 *

 *     public void removeVetoableChangeListener(VetoableChangeListener listener) {

 *         this.vcs.removeVetoableChangeListener(listener);

 *     }

 *

 *     private String value;

 *

 *     public String getValue() {

 *         return this.value;

 *     }

 *

 *     public void setValue(String newValue) throws PropertyVetoException {

 *         String oldValue = this.value;

 *         this.vcs.fireVetoableChange("value", oldValue, newValue);

 *         this.value = newValue;

 *     }

 *

 *     [...]

 * }

 * </pre>

 * <p>

 * A {@code VetoableChangeSupport} instance is thread-safe.

 * <p>

 * This class is serializable.  When it is serialized it will save

 * (and restore) any listeners that are themselves serializable.  Any

 * non-serializable listeners will be skipped during serialization.

 *

 * @see PropertyChangeSupport

 */

public class VetoableChangeSupport implements Serializable {

    private VetoableChangeListenerMap map = new VetoableChangeListenerMap();

    /**

     * Constructs a <code>VetoableChangeSupport</code> object.

     *

     * @param sourceBean  The bean to be given as the source for any events.

     */

    public VetoableChangeSupport(Object sourceBean) {

        if (sourceBean == null) {

            throw new NullPointerException();

        }

        source = sourceBean;

    }

    /**

     * Add a VetoableChangeListener to the listener list.

     * The listener is registered for all properties.

     * The same listener object may be added more than once, and will be called

     * as many times as it is added.

     * If <code>listener</code> is null, no exception is thrown and no action

     * is taken.

     *

     * @param listener  The VetoableChangeListener to be added

     */

    public void addVetoableChangeListener(VetoableChangeListener listener) {

        if (listener == null) {

            return;

        }

        if (listener instanceof VetoableChangeListenerProxy) {

            VetoableChangeListenerProxy proxy =

                    (VetoableChangeListenerProxy)listener;

            // Call two argument add method.

            addVetoableChangeListener(proxy.getPropertyName(),

                                      proxy.getListener());

        } else {

            this.map.add(null, listener);

        }

    }

    /**

     * Remove a VetoableChangeListener from the listener list.

     * This removes a VetoableChangeListener that was registered

     * for all properties.

     * If <code>listener</code> was added more than once to the same event

     * source, it will be notified one less time after being removed.

     * If <code>listener</code> is null, or was never added, no exception is

     * thrown and no action is taken.

     *

     * @param listener  The VetoableChangeListener to be removed

     */

    public void removeVetoableChangeListener(VetoableChangeListener listener) {

        if (listener == null) {

            return;

        }

        if (listener instanceof VetoableChangeListenerProxy) {

            VetoableChangeListenerProxy proxy =

                    (VetoableChangeListenerProxy)listener;

            // Call two argument remove method.

            removeVetoableChangeListener(proxy.getPropertyName(),

                                         proxy.getListener());

        } else {

            this.map.remove(null, listener);

        }

    }

    /**

     * Returns an array of all the listeners that were added to the

     * VetoableChangeSupport object with addVetoableChangeListener().

     * <p>

     * If some listeners have been added with a named property, then

     * the returned array will be a mixture of VetoableChangeListeners

     * and <code>VetoableChangeListenerProxy</code>s. If the calling

     * method is interested in distinguishing the listeners then it must

     * test each element to see if it's a

     * <code>VetoableChangeListenerProxy</code>, perform the cast, and examine

     * the parameter.

     *

     * <pre>

     * VetoableChangeListener[] listeners = bean.getVetoableChangeListeners();

     * for (int i = 0; i < listeners.length; i++) {

     *        if (listeners[i] instanceof VetoableChangeListenerProxy) {

     *     VetoableChangeListenerProxy proxy =

     *                    (VetoableChangeListenerProxy)listeners[i];

     *     if (proxy.getPropertyName().equals("foo")) {

     *       // proxy is a VetoableChangeListener which was associated

     *       // with the property named "foo"

     *     }

     *   }

     * }

     *</pre>

     *

     * @see VetoableChangeListenerProxy

     * @return all of the <code>VetoableChangeListeners</code> added or an

     *         empty array if no listeners have been added

     * @since 1.4

     */

    public VetoableChangeListener[] getVetoableChangeListeners(){

        return this.map.getListeners();

    }

    /**

     * Add a VetoableChangeListener for a specific property.  The listener

     * will be invoked only when a call on fireVetoableChange names that

     * specific property.

     * The same listener object may be added more than once.  For each

     * property,  the listener will be invoked the number of times it was added

     * for that property.

     * If <code>propertyName</code> or <code>listener</code> is null, no

     * exception is thrown and no action is taken.

     *

     * @param propertyName  The name of the property to listen on.

     * @param listener  The VetoableChangeListener to be added

     */

    public void addVetoableChangeListener(

                                String propertyName,

                VetoableChangeListener listener) {

        if (listener == null || propertyName == null) {

            return;

        }

        listener = this.map.extract(listener);

        if (listener != null) {

            this.map.add(propertyName, listener);

        }

    }

    /**

     * Remove a VetoableChangeListener for a specific property.

     * If <code>listener</code> was added more than once to the same event

     * source for the specified property, it will be notified one less time

     * after being removed.

     * If <code>propertyName</code> is null, no exception is thrown and no

     * action is taken.

     * If <code>listener</code> is null, or was never added for the specified

     * property, no exception is thrown and no action is taken.

     *

     * @param propertyName  The name of the property that was listened on.

     * @param listener  The VetoableChangeListener to be removed

     */

    public void removeVetoableChangeListener(

                                String propertyName,

                VetoableChangeListener listener) {

        if (listener == null || propertyName == null) {

            return;

        }

        listener = this.map.extract(listener);

        if (listener != null) {

            this.map.remove(propertyName, listener);

        }

    }

    /**

     * Returns an array of all the listeners which have been associated

     * with the named property.

     *

     * @param propertyName  The name of the property being listened to

     * @return all the <code>VetoableChangeListeners</code> associated with

     *         the named property.  If no such listeners have been added,

     *         or if <code>propertyName</code> is null, an empty array is

     *         returned.

     * @since 1.4

     */

    public VetoableChangeListener[] getVetoableChangeListeners(String propertyName) {

        return this.map.getListeners(propertyName);

    }

    /**

     * Reports a constrained property update to listeners

     * that have been registered to track updates of

     * all properties or a property with the specified name.

     * <p>

     * Any listener can throw a {@code PropertyVetoException} to veto the update.

     * If one of the listeners vetoes the update, this method passes

     * a new "undo" {@code PropertyChangeEvent} that reverts to the old value

     * to all listeners that already confirmed this update

     * and throws the {@code PropertyVetoException} again.

     * <p>

     * No event is fired if old and new values are equal and non-null.

     * <p>

     * This is merely a convenience wrapper around the more general

     * {@link #fireVetoableChange(PropertyChangeEvent)} method.

     *

     * @param propertyName  the programmatic name of the property that is about to change

     * @param oldValue      the old value of the property

     * @param newValue      the new value of the property

     * @throws PropertyVetoException if one of listeners vetoes the property update

     */

    public void fireVetoableChange(String propertyName, Object oldValue, Object newValue)

            throws PropertyVetoException {

        if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {

            fireVetoableChange(new PropertyChangeEvent(this.source, propertyName, oldValue, newValue));

        }

    }

    /**

     * Reports an integer constrained property update to listeners

     * that have been registered to track updates of

     * all properties or a property with the specified name.

     * <p>

     * Any listener can throw a {@code PropertyVetoException} to veto the update.

     * If one of the listeners vetoes the update, this method passes

     * a new "undo" {@code PropertyChangeEvent} that reverts to the old value

     * to all listeners that already confirmed this update

     * and throws the {@code PropertyVetoException} again.

     * <p>

     * No event is fired if old and new values are equal.

     * <p>

     * This is merely a convenience wrapper around the more general

     * {@link #fireVetoableChange(String, Object, Object)} method.

     *

     * @param propertyName  the programmatic name of the property that is about to change

     * @param oldValue      the old value of the property

     * @param newValue      the new value of the property

     * @throws PropertyVetoException if one of listeners vetoes the property update

     */

    public void fireVetoableChange(String propertyName, int oldValue, int newValue)

            throws PropertyVetoException {

        if (oldValue != newValue) {

            fireVetoableChange(propertyName, Integer.valueOf(oldValue), Integer.valueOf(newValue));

        }

    }

    /**

     * Reports a boolean constrained property update to listeners

     * that have been registered to track updates of

     * all properties or a property with the specified name.

     * <p>

     * Any listener can throw a {@code PropertyVetoException} to veto the update.

     * If one of the listeners vetoes the update, this method passes

     * a new "undo" {@code PropertyChangeEvent} that reverts to the old value

     * to all listeners that already confirmed this update

     * and throws the {@code PropertyVetoException} again.

     * <p>

     * No event is fired if old and new values are equal.

     * <p>

     * This is merely a convenience wrapper around the more general

     * {@link #fireVetoableChange(String, Object, Object)} method.

     *

     * @param propertyName  the programmatic name of the property that is about to change

     * @param oldValue      the old value of the property

     * @param newValue      the new value of the property

     * @throws PropertyVetoException if one of listeners vetoes the property update

     */

    public void fireVetoableChange(String propertyName, boolean oldValue, boolean newValue)

            throws PropertyVetoException {

        if (oldValue != newValue) {

            fireVetoableChange(propertyName, Boolean.valueOf(oldValue), Boolean.valueOf(newValue));

        }

    }

    /**

     * Fires a property change event to listeners

     * that have been registered to track updates of

     * all properties or a property with the specified name.

     * <p>

     * Any listener can throw a {@code PropertyVetoException} to veto the update.

     * If one of the listeners vetoes the update, this method passes

     * a new "undo" {@code PropertyChangeEvent} that reverts to the old value

     * to all listeners that already confirmed this update

     * and throws the {@code PropertyVetoException} again.

     * <p>

     * No event is fired if the given event's old and new values are equal and non-null.

     *

     * @param event  the {@code PropertyChangeEvent} to be fired

     * @throws PropertyVetoException if one of listeners vetoes the property update

     */

    public void fireVetoableChange(PropertyChangeEvent event)

            throws PropertyVetoException {

        Object oldValue = event.getOldValue();

        Object newValue = event.getNewValue();

        if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {

            String name = event.getPropertyName();

            VetoableChangeListener[] common = this.map.get(null);

            VetoableChangeListener[] named = (name != null)

                        ? this.map.get(name)

                        : null;

            VetoableChangeListener[] listeners;

            if (common == null) {

                listeners = named;

            }

            else if (named == null) {

                listeners = common;

            }

            else {

                listeners = new VetoableChangeListener[common.length + named.length];

                System.arraycopy(common, 0, listeners, 0, common.length);

                System.arraycopy(named, 0, listeners, common.length, named.length);

            }

            if (listeners != null) {

                int current = 0;

                try {

                    while (current < listeners.length) {

                        listeners[current].vetoableChange(event);

                        current++;

                    }

                }

                catch (PropertyVetoException veto) {

                    event = new PropertyChangeEvent(this.source, name, newValue, oldValue);

                    for (int i = 0; i < current; i++) {

                        try {

                            listeners[i].vetoableChange(event);

                        }

                        catch (PropertyVetoException exception) {

                            // ignore exceptions that occur during rolling back

                        }

                    }

                    throw veto; // rethrow the veto exception

                }

            }

        }

    }

    /**

     * Check if there are any listeners for a specific property, including

     * those registered on all properties.  If <code>propertyName</code>

     * is null, only check for listeners registered on all properties.

     *

     * @param propertyName  the property name.

     * @return true if there are one or more listeners for the given property

     */

    public boolean hasListeners(String propertyName) {

        return this.map.hasListeners(propertyName);

    }

    /**

     * @serialData Null terminated list of <code>VetoableChangeListeners</code>.

     * <p>

     * At serialization time we skip non-serializable listeners and

     * only serialize the serializable listeners.

     */

    private void writeObject(ObjectOutputStream s) throws IOException {

        Hashtable<String, VetoableChangeSupport> children = null;

        VetoableChangeListener[] listeners = null;

        synchronized (this.map) {

            for (Entry<String, VetoableChangeListener[]> entry : this.map.getEntries()) {

                String property = entry.getKey();

                if (property == null) {

                    listeners = entry.getValue();

                } else {

                    if (children == null) {

                        children = new Hashtable<String, VetoableChangeSupport>();

                    }

                    VetoableChangeSupport vcs = new VetoableChangeSupport(this.source);

                    vcs.map.set(null, entry.getValue());

                    children.put(property, vcs);

                }

            }

        }

        ObjectOutputStream.PutField fields = s.putFields();

        fields.put("children", children);

        fields.put("source", this.source);

        fields.put("vetoableChangeSupportSerializedDataVersion", 2);

        s.writeFields();

        if (listeners != null) {

            for (VetoableChangeListener l : listeners) {

                if (l instanceof Serializable) {

                    s.writeObject(l);

                }

            }

        }

        s.writeObject(null);

    }

    private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException {

        this.map = new VetoableChangeListenerMap();

        ObjectInputStream.GetField fields = s.readFields();

        Hashtable<String, VetoableChangeSupport> children = (Hashtable<String, VetoableChangeSupport>) fields.get("children", null);

        this.source = fields.get("source", null);

        fields.get("vetoableChangeSupportSerializedDataVersion", 2);

        Object listenerOrNull;

        while (null != (listenerOrNull = s.readObject())) {

            this.map.add(null, (VetoableChangeListener)listenerOrNull);

        }

        if (children != null) {

            for (Entry<String, VetoableChangeSupport> entry : children.entrySet()) {

                for (VetoableChangeListener listener : entry.getValue().getVetoableChangeListeners()) {

                    this.map.add(entry.getKey(), listener);

                }

            }

        }

    }

    /**

     * The object to be provided as the "source" for any generated events.

     */

    private Object source;

    /**

     * @serialField children                                   Hashtable

     * @serialField source                                     Object

     * @serialField propertyChangeSupportSerializedDataVersion int

     */

    private static final ObjectStreamField[] serialPersistentFields = {

            new ObjectStreamField("children", Hashtable.class),

            new ObjectStreamField("source", Object.class),

            new ObjectStreamField("vetoableChangeSupportSerializedDataVersion", Integer.TYPE)

    };

    /**

     * Serialization version ID, so we're compatible with JDK 1.1

     */

    static final long serialVersionUID = -5090210921595982017L;

    /**

     * This is a {@link ChangeListenerMap ChangeListenerMap} implementation

     * that works with {@link VetoableChangeListener VetoableChangeListener} objects.

     */

    private static final class VetoableChangeListenerMap extends ChangeListenerMap<VetoableChangeListener> {

        private static final VetoableChangeListener[] EMPTY = {};

        /**

         * Creates an array of {@link VetoableChangeListener VetoableChangeListener} objects.

         * This method uses the same instance of the empty array

         * when {@code length} equals {@code 0}.

         *

         * @param length  the array length

         * @return        an array with specified length

         */

        @Override

        protected VetoableChangeListener[] newArray(int length) {

            return (0 < length)

                    ? new VetoableChangeListener[length]

                    : EMPTY;

        }

        /**

         * Creates a {@link VetoableChangeListenerProxy VetoableChangeListenerProxy}

         * object for the specified property.