/*

  * 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.application.viewstate;

 import java.util.Map;

 import javax.faces.context.ExternalContext;

 import javax.faces.context.FacesContext;

 import org.apache.myfaces.shared.renderkit.RendererUtils;

 /**

  *

  */

 class CounterKeyFactory extends KeyFactory<Integer>

 {

     /**

      * Take the counter from session scope and increment

      *

      * @param facesContext

      * @return

      */

     @Override

     public Integer generateKey(FacesContext facesContext)

     {

         ExternalContext externalContext = facesContext.getExternalContext();

         Object sessionObj = externalContext.getSession(true);

         Integer sequence = null;

         // synchronized to increase sequence if multiple requests

         // are handled at the same time for the session

         synchronized (sessionObj) 

         {

             Map<String, Object> map = externalContext.getSessionMap();

             sequence = (Integer) map.get(RendererUtils.SEQUENCE_PARAM);

             if (sequence == null || sequence.intValue() == Integer.MAX_VALUE)

             {

                 sequence = Integer.valueOf(1);

             }

             else

             {

                 sequence = Integer.valueOf(sequence.intValue() + 1);

             }

             map.put(RendererUtils.SEQUENCE_PARAM, sequence);

         }

         return sequence;

     }

     public String encode(Integer sequence)

     {

         return Integer.toString(sequence, Character.MAX_RADIX);

     }

     public Integer decode(String serverStateId)

     {

         return Integer.valueOf((String) serverStateId, Character.MAX_RADIX);

     }

 }