/*

 * 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;

import org.apidesign.bck2brwsr.emul.lang.System;

/**

 * 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;

    }

}