/*

  * Copyright (c) 2007, 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.util.ArrayList;

 import java.util.Collections;

 import java.util.EventListener;

 import java.util.EventListenerProxy;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 import java.util.Map.Entry;

 import java.util.Set;

 /**

  * This is an abstract class that provides base functionality

  * for the {@link PropertyChangeSupport PropertyChangeSupport} class

  * and the {@link VetoableChangeSupport VetoableChangeSupport} class.

  *

  * @see PropertyChangeListenerMap

  * @see VetoableChangeListenerMap

  *

  * @author Sergey A. Malenkov

  */

 abstract class ChangeListenerMap<L extends EventListener> {

     private Map<String, L[]> map;

     /**

      * Creates an array of listeners.

      * This method can be optimized by using

      * the same instance of the empty array

      * when {@code length} is equal to {@code 0}.

      *

      * @param length  the array length

      * @return        an array with specified length

      */

     protected abstract L[] newArray(int length);

     /**

      * Creates a proxy listener for the specified property.

      *

      * @param name      the name of the property to listen on

      * @param listener  the listener to process events

      * @return          a proxy listener

      */

     protected abstract L newProxy(String name, L listener);

     /**

      * Adds a listener to the list of listeners for the specified property.

      * This listener is called as many times as it was added.

      *

      * @param name      the name of the property to listen on

      * @param listener  the listener to process events

      */

     public final synchronized void add(String name, L listener) {

         if (this.map == null) {

             this.map = new HashMap<String, L[]>();

         }

         L[] array = this.map.get(name);

         int size = (array != null)

                 ? array.length

                 : 0;

         L[] clone = newArray(size + 1);

         clone[size] = listener;

         if (array != null) {

             System.arraycopy(array, 0, clone, 0, size);

         }

         this.map.put(name, clone);

     }

     /**

      * Removes a listener from the list of listeners for the specified property.

      * If the listener was added more than once to the same event source,

      * this listener will be notified one less time after being removed.

      *

      * @param name      the name of the property to listen on

      * @param listener  the listener to process events

      */

     public final synchronized void remove(String name, L listener) {

         if (this.map != null) {

             L[] array = this.map.get(name);

             if (array != null) {

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

                     if (listener.equals(array[i])) {

                         int size = array.length - 1;

                         if (size > 0) {

                             L[] clone = newArray(size);

                             System.arraycopy(array, 0, clone, 0, i);

                             System.arraycopy(array, i + 1, clone, i, size - i);

                             this.map.put(name, clone);

                         }

                         else {

                             this.map.remove(name);

                             if (this.map.isEmpty()) {

                                 this.map = null;

                             }

                         }

                         break;

                     }

                 }

             }

         }

     }

     /**

      * Returns the list of listeners for the specified property.

      *

      * @param name  the name of the property

      * @return      the corresponding list of listeners

      */

     public final synchronized L[] get(String name) {

         return (this.map != null)

                 ? this.map.get(name)

                 : null;

     }

     /**

      * Sets new list of listeners for the specified property.

      *

      * @param name       the name of the property

      * @param listeners  new list of listeners

      */

     public final void set(String name, L[] listeners) {

         if (listeners != null) {

             if (this.map == null) {

                 this.map = new HashMap<String, L[]>();

             }

             this.map.put(name, listeners);

         }

         else if (this.map != null) {

             this.map.remove(name);

             if (this.map.isEmpty()) {

                 this.map = null;

             }

         }

     }

     /**

      * Returns all listeners in the map.

      *

      * @return an array of all listeners

      */

     public final synchronized L[] getListeners() {

         if (this.map == null) {

             return newArray(0);

         }

         List<L> list = new ArrayList<L>();

         L[] listeners = this.map.get(null);

         if (listeners != null) {

             for (L listener : listeners) {

                 list.add(listener);

             }

         }

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

             String name = entry.getKey();

             if (name != null) {

                 for (L listener : entry.getValue()) {

                     list.add(newProxy(name, listener));

                 }

             }

         }

         return list.toArray(newArray(list.size()));

     }

     /**

      * Returns listeners that have been associated with the named property.

      *

      * @param name  the name of the property

      * @return an array of listeners for the named property

      */

     public final L[] getListeners(String name) {

         if (name != null) {

             L[] listeners = get(name);

             if (listeners != null) {

                 return listeners.clone();

             }

         }

         return newArray(0);

     }

     /**

      * Indicates whether the map contains

      * at least one listener to be notified.

      *

      * @param name  the name of the property

      * @return      {@code true} if at least one listener exists or

      *              {@code false} otherwise

      */

     public final synchronized boolean hasListeners(String name) {

         if (this.map == null) {

             return false;

         }

         L[] array = this.map.get(null);

         return (array != null) || ((name != null) && (null != this.map.get(name)));

     }

     /**

      * Returns a set of entries from the map.

      * Each entry is a pair consisted of the property name

      * and the corresponding list of listeners.

      *

      * @return a set of entries from the map

      */

     public final Set<Entry<String, L[]>> getEntries() {

         return (this.map != null)

                 ? this.map.entrySet()

                 : Collections.<Entry<String, L[]>>emptySet();

     }

     /**

      * Extracts a real listener from the proxy listener.

      * It is necessary because default proxy class is not serializable.

      *

      * @return a real listener

      */

     public final L extract(L listener) {

         while (listener instanceof EventListenerProxy) {

             EventListenerProxy<L> proxy = (EventListenerProxy<L>) listener;

             listener = proxy.getListener();

         }

         return listener;

     }

 }