/*

  * Copyright 1999-2001,2004 The Apache Software Foundation.

  * 

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  * 

  *      http://www.apache.org/licenses/LICENSE-2.0

  * 

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.apache.commons.workflow.util;

 import java.util.Map;

 import org.apache.commons.workflow.Scope;

 import org.apache.commons.workflow.ScopeEvent;

 import org.apache.commons.workflow.ScopeListener;

 /**

  * <strong>ScopeSupport</strong> is a convenience class for managing the

  * firing of <code>ScopeEvents</code> to registered

  * <code>ScopeListeners</code>.

  *

  * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $

  * @author Craig R. McClanahan

  */

 public class ScopeSupport {

     // ----------------------------------------------------------- Constructors

     /**

      * Construct a new ScopeSupport object associated with the specified Scope.

      *

      * @param scope Scope for whom we will fire events

      */

     public ScopeSupport(Scope scope) {

         super();

         this.scope = scope;

     }

     // ----------------------------------------------------- Instance Variables

     /**

      * The set of registered <code>ScopeListener</code> event listeners.

      */

     protected ScopeListener listeners[] = new ScopeListener[0];

     /**

      * The <code>Scope</code> for whom we will fire events.

      */

     protected Scope scope = null;

     // ------------------------------------------------- Event Listener Methods

     /**

      * Add a listener that is notified each time beans are added,

      * replaced, or removed in this scope.

      *

      * @param listener The ScopeListener to be added

      */

     public void addScopeListener(ScopeListener listener) {

       synchronized (listeners) {

           ScopeListener results[] =

             new ScopeListener[listeners.length + 1];

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

           results[listeners.length] = listener;

           listeners = results;

       }

     }

     /**

      * Remove a listener that is notified each time beans are added,

      * replaced, or removed in this scope.

      *

      * @param listener The ScopeListener to be removed

      */

     public void removeScopeListener(ScopeListener listener) {

         synchronized (listeners) {

             int n = -1;

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

                 if (listeners[i] == listener) {

                     n = i;

                     break;

                 }

             }

             if (n < 0)

                 return;

             ScopeListener results[] =

               new ScopeListener[listeners.length - 1];

             int j = 0;

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

                 if (i != n)

                     results[j++] = listeners[i];

             }

             listeners = results;

         }

     }

     // --------------------------------------------------- Event Firing Methods

     /**

      * Fire a <code>beanAdded()</code> event to all registered listeners.

      *

      * @param key Key of the bean that was added

      * @param value Value of the bean that was added

      */

     public void fireBeanAdded(String key, Object value) {

         if (listeners.length == 0)

             return;

         ScopeEvent event = new ScopeEvent(scope, key, value);

         ScopeListener interested[] = null;

         synchronized (listeners) {

             interested = (ScopeListener[]) listeners.clone();

         }

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

             interested[i].beanAdded(event);

     }

     /**

      * Fire a <code>beanRemoved()</code> event to all registered listeners.

      *

      * @param key Key of the bean that was removed

      * @param value Value of the bean that was removed

      */

     public void fireBeanRemoved(String key, Object value) {

         if (listeners.length == 0)

             return;

         ScopeEvent event = new ScopeEvent(scope, key, value);

         ScopeListener interested[] = null;

         synchronized (listeners) {

             interested = (ScopeListener[]) listeners.clone();

         }

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

             interested[i].beanRemoved(event);

     }

     /**

      * Fire a <code>beanReplaced()</code> event to all registered listeners.

      *

      * @param key Key of the bean that was replaced

      * @param value Old value of the bean that was replaced

      */

     public void fireBeanReplaced(String key, Object value) {

         if (listeners.length == 0)

             return;

         ScopeEvent event = new ScopeEvent(scope, key, value);

         ScopeListener interested[] = null;

         synchronized (listeners) {

             interested = (ScopeListener[]) listeners.clone();

         }

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

             interested[i].beanReplaced(event);

     }

     /**

      * Fire a <code>scopeCleared()</code> event to all registered listeners.

      */

     public void fireScopeCleared() {

         if (listeners.length == 0)

             return;

         ScopeEvent event = new ScopeEvent(scope, null, null);

         ScopeListener interested[] = null;

         synchronized (listeners) {

             interested = (ScopeListener[]) listeners.clone();

         }

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

             interested[i].scopeCleared(event);

     }

 }