/*
    * 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.Context;
  import org.apache.commons.workflow.ContextEvent;
  import org.apache.commons.workflow.ContextListener;
  import org.apache.commons.workflow.Step;
  import org.apache.commons.workflow.StepException;
  
  
  /**
   * <strong>ContextSupport</strong> is a convenience class for managing the
   * firing of <code>ContextEvents</code> to registered
   * <code>ContextListeners</code>.
   *
   * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
   * @author Craig R. McClanahan
   */
  
  public class ContextSupport {
  
  
      // ----------------------------------------------------------- Constructors
  
  
      /**
       * Construct a new ContextSupport object associated with the
       * specified Context.
       *
       * @param context Context for whom we will fire events
       */
      public ContextSupport(Context context) {
  
          super();
          this.context = context;
  
      }
  
  
      // ----------------------------------------------------- Instance Variables
  
  
      /**
       * The set of registered <code>ContextListener</code> event listeners.
       */
      protected ContextListener listeners[] = new ContextListener[0];
  
  
      /**
       * The <code>Context</code> for whom we will fire events.
       */
      protected Context context = null;
  
  
      // ------------------------------------------------- Event Listener Methods
  
  
      /**
       * Add a listener that is notified each time beans are added,
       * replaced, or removed in this context.
       *
       * @param listener The ContextListener to be added
       */
      public void addContextListener(ContextListener listener) {
  
        synchronized (listeners) {
            ContextListener results[] =
              new ContextListener[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 context.
       *
       * @param listener The ContextListener to be removed
       */
     public void removeContextListener(ContextListener 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;
             ContextListener results[] =
               new ContextListener[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>afterActivity</code> event to all registered listeners.
      *
      * @param step Step that was executed last
      */
     public void fireAfterActivity(Step step) {
 
         if (listeners.length == 0)
             return;
         ContextEvent event = new ContextEvent(context, step);
         ContextListener interested[] = null;
         synchronized (listeners) {
             interested = (ContextListener[]) listeners.clone();
         }
         for (int i = 0; i < interested.length; i++)
             interested[i].afterActivity(event);
 
     }
 
 
     /**
      * Fire a <code>afterActivity</code> event to all registered listeners.
      *
      * @param step Step that was executed last
      * @param exception StepException thrown by the last Step
      */
     public void fireAfterActivity(Step step, StepException exception) {
 
         if (listeners.length == 0)
             return;
         ContextEvent event = new ContextEvent(context, step, exception);
         ContextListener interested[] = null;
         synchronized (listeners) {
             interested = (ContextListener[]) listeners.clone();
         }
         for (int i = 0; i < interested.length; i++)
             interested[i].afterActivity(event);
 
     }
 
 
     /**
      * Fire a <code>afterStep</code> event to all registered listeners.
      *
      * @param step Step that was executed
      */
     public void fireAfterStep(Step step) {
 
         if (listeners.length == 0)
             return;
         ContextEvent event = new ContextEvent(context, step);
         ContextListener interested[] = null;
         synchronized (listeners) {
             interested = (ContextListener[]) listeners.clone();
         }
         for (int i = 0; i < interested.length; i++)
             interested[i].afterStep(event);
 
     }
 
 
     /**
      * Fire a <code>afterStep</code> event to all registered listeners.
      *
      * @param step Step that was executed
      * @param exception StepException thrown by the executed step
      */
     public void fireAfterStep(Step step, StepException exception) {
 
         if (listeners.length == 0)
             return;
         ContextEvent event = new ContextEvent(context, step, exception);
         ContextListener interested[] = null;
         synchronized (listeners) {
             interested = (ContextListener[]) listeners.clone();
         }
         for (int i = 0; i < interested.length; i++)
             interested[i].afterStep(event);
 
     }
 
 
     /**
      * Fire a <code>beforeActivity</code> event to all registered listeners.
      *
      * @param step Step that will be executed first
      */
     public void fireBeforeActivity(Step step) {
 
         if (listeners.length == 0)
             return;
         ContextEvent event = new ContextEvent(context, step);
         ContextListener interested[] = null;
         synchronized (listeners) {
             interested = (ContextListener[]) listeners.clone();
         }
         for (int i = 0; i < interested.length; i++)
             interested[i].beforeActivity(event);
 
     }
 
 
     /**
      * Fire a <code>beforeStep</code> event to all registered listeners.
      *
      * @param step Step that is about to be executed
      */
     public void fireBeforeStep(Step step) {
 
         if (listeners.length == 0)
             return;
         ContextEvent event = new ContextEvent(context, step);
         ContextListener interested[] = null;
         synchronized (listeners) {
             interested = (ContextListener[]) listeners.clone();
         }
         for (int i = 0; i < interested.length; i++)
             interested[i].beforeStep(event);
 
     }
 
 
 }