/*

 * Copyright (c) 2005, 2015, 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

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 * questions.

 */

package com.sun.java.accessibility.util;

import java.util.*;

import java.beans.*;

import java.awt.*;

import java.awt.event.*;

import javax.accessibility.*;

/**

 * <P>The {@code AccessibilityListenerList} is a copy of the Swing

 * {@link javax.swing.event.EventListenerList EventListerList} class.

 *

 */

public class AccessibilityListenerList {

    /* A null array to be shared by all empty listener lists */

    private final static Object[] NULL_ARRAY = new Object[0];

    /**

     * The list of listener type, listener pairs

     */

    protected transient Object[] listenerList = NULL_ARRAY;

    /**

     * Passes back the event listener list as an array of listener type, listener pairs.

     * Note that for performance reasons, this implementation passes back the actual

     * data structure in which the listener data is stored internally. This method

     * is guaranteed to pass back a non-null array, so that no null-checking

     * is required in fire methods. A zero-length array of Object is returned if

     * there are currently no listeners.

     * <p>

     * Absolutely no modification of the data contained in this array should be

     * made.  If any such manipulation is necessary, it should be done on a copy

     * of the array returned rather than the array itself.

     *

     * @return an array of listener type, listener pairs.

     */

    public Object[] getListenerList() {

        return listenerList;

    }

    /**

     * Returns the total number of listeners for this listener list.

     *

     * @return the total number of listeners for this listener list.

     */

    public int getListenerCount() {

        return listenerList.length/2;

    }

    /**

     * Return the total number of listeners of the supplied type

     * for this listener list.

     *

     * @param t the type of the listener to be counted

     * @return the number of listeners found

     */

    public int getListenerCount(Class<? extends EventListener> t) {

        int count = 0;

        Object[] lList = listenerList;

        for (int i = 0; i < lList.length; i+=2) {

            if (t == (Class)lList[i])

                count++;

        }

        return count;

    }

    /**

     * Add the listener as a listener of the specified type.

     *

     * @param t the type of the listener to be added

     * @param l the listener to be added

     */

    public synchronized void add(Class<? extends EventListener> t, EventListener l) {

        if (!t.isInstance(l)) {

            throw new IllegalArgumentException("Listener " + l +

                                         " is not of type " + t);

        }

        if (l ==null) {

            throw new IllegalArgumentException("Listener " + l +

                                         " is null");

        }

        if (listenerList == NULL_ARRAY) {

            // if this is the first listener added,

            // initialize the lists

            listenerList = new Object[] { t, l };

        } else {

            // Otherwise copy the array and add the new listener

            int i = listenerList.length;

            Object[] tmp = new Object[i+2];

            System.arraycopy(listenerList, 0, tmp, 0, i);

            tmp[i] = t;

            tmp[i+1] = l;

            listenerList = tmp;

        }

    }

    /**

     * Remove the listener as a listener of the specified type.

     *

     * @param t the type of the listener to be removed

     * @param l the listener to be removed

     */

    public synchronized void remove(Class<? extends EventListener> t, EventListener l) {

        if (!t.isInstance(l)) {

            throw new IllegalArgumentException("Listener " + l +

                                         " is not of type " + t);

        }

        if (l ==null) {

            throw new IllegalArgumentException("Listener " + l +

                                         " is null");

        }

        // Is l on the list?

        int index = -1;

        for (int i = listenerList.length-2; i>=0; i-=2) {

            if ((listenerList[i]==t) && (listenerList[i+1] == l)) {

                index = i;

                break;

            }

        }

        // If so,  remove it

        if (index != -1) {

            Object[] tmp = new Object[listenerList.length-2];

            // Copy the list up to index

            System.arraycopy(listenerList, 0, tmp, 0, index);

            // Copy from two past the index, up to

            // the end of tmp (which is two elements

            // shorter than the old list)

            if (index < tmp.length)

                System.arraycopy(listenerList, index+2, tmp, index,

                                 tmp.length - index);

            // set the listener array to the new array or null

            listenerList = (tmp.length == 0) ? NULL_ARRAY : tmp;

            }

    }

    /**

     * Return a string representation of the {@code AccessibilityListenerList}.

     *

     * @return a string representation of the {@code AccessibilityListenerList}.

     */

    public String toString() {

        Object[] lList = listenerList;

        String s = "EventListenerList: ";

        s += lList.length/2 + " listeners: ";

        for (int i = 0 ; i <= lList.length-2 ; i+=2) {

            s += " type " + ((Class)lList[i]).getName();

            s += " listener " + lList[i+1];

        }

        return s;

    }

}