/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.myfaces.custom.valueChangeNotifier;
  
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import javax.faces.FacesException;
  import javax.faces.context.FacesContext;
  import javax.faces.el.MethodBinding;
  import javax.faces.el.MethodNotFoundException;
  import javax.faces.event.AbortProcessingException;
  import javax.faces.event.ValueChangeEvent;
  
  /**
   * Manage valueChange events to be fired after the UPDATE_MODEL phase.
   * 
   * @author Mario Ivankovits <imario - at - apache.org>  (latest modification by $Author$)
   * @version $Revision$ $Date$
   */
  public final class ValueChangeManager
  {
      public final static Class[] SIGNATURE = new Class[]
                                                          { ValueChangeEvent.class };
      private final static String VCL_MANAGER = "_VCL_MANAGER_"
              + ValueChangeNotifierTag.class.getName();
  
      private List events = new ArrayList(10);
  
      private static class Entry
      {
          private final String method;
          private final ValueChangeEvent event;
          private final List restoreStateCommands;
  
          public Entry(String method,
                  ValueChangeEvent event,
                  List restoreStateCommands)
          {
              this.method = method;
              this.event = event;
              this.restoreStateCommands = restoreStateCommands;
          }
      }
  
      private ValueChangeManager()
      {
      }
  
      /**
       * add a new event 
       */
      public void addEvent(String method,
              ValueChangeEvent event,
              List restoreStateCommands)
      {
          events.add(new Entry(method, event, restoreStateCommands));
      }
  
      /**
       * walk through list and fire collected events 
       */
      public void fireEvents(FacesContext context)
      {
          try
          {
              Iterator iterEvents = events.iterator();
              while (iterEvents.hasNext())
              {
                  Entry entry = (Entry) iterEvents.next();
  
                  saveCurrentStates(entry.restoreStateCommands);
                  
                  try
                  {
                      restoreEventStates(entry.restoreStateCommands);
                      
                      MethodBinding mb = context.getApplication().createMethodBinding(entry.method, SIGNATURE);
                      mb.invoke(context, new Object[] { entry.event });
                  }
                  catch (MethodNotFoundException e)
                 {
                     throw new FacesException(e);
                 }
                 catch (AbortProcessingException e)
                 {
                     // ignore any other value change event
                     return;
                 }
                 finally
                 {
                     restoreCurrentStates(entry.restoreStateCommands);
                 }
             }
         }
         finally
         {
             events.clear();            
         }
     }
 
     protected void saveCurrentStates(List restoreStateCommands)
     {
         for (int i = 0; i<restoreStateCommands.size(); i++)
         {
             RestoreStateCommand cmd = (RestoreStateCommand) restoreStateCommands.get(i);
             cmd.saveCurrentState();
         }
     }
     
     protected void restoreCurrentStates(List restoreStateCommands)
     {
         for (int i = restoreStateCommands.size()-1; i>=0; i--)
         {
             RestoreStateCommand cmd = (RestoreStateCommand) restoreStateCommands.get(i);
             cmd.restoreCurrentState();
         }
     }
 
     protected void restoreEventStates(List restoreStateCommands)
     {
         for (int i = restoreStateCommands.size()-1; i>=0; i--)
         {
             RestoreStateCommand cmd = (RestoreStateCommand) restoreStateCommands.get(i);
             cmd.restoreEventState();
         }
     }
 
     /**
      * check if the current request has a manager.<br />
      * The current request has a manager if, and only if it
      * collected valueChange events 
      */
     public static boolean hasManager(FacesContext context)
     {
         Map requestMap = context.getExternalContext().getRequestMap();
         return requestMap.get(VCL_MANAGER) != null;
     }
 
     /**
      * get the manager for this request. Create one if needed. 
      */
     public static ValueChangeManager getManager(FacesContext context)
     {
         Map requestMap = context.getExternalContext().getRequestMap();
         ValueChangeManager manager = (ValueChangeManager) requestMap
                 .get(VCL_MANAGER);
         if (manager == null)
         {
             manager = new ValueChangeManager();
             requestMap.put(VCL_MANAGER, manager);
         }
 
         return manager;
     }
 }