/*
    * 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.webapp;
  
  import java.util.logging.Level;
  import java.util.logging.Logger;
  import javax.el.ExpressionFactory;
  import javax.faces.FacesException;
  import javax.faces.context.ExternalContext;
  import javax.servlet.ServletContext;
  /**
   * This initializer initializes only Facelets. Specially checks for
   * org.apache.myfaces.EXPRESSION_FACTORY parameter.
   * 
   * @author Martin Koci
   */
  public class FaceletsInitilializer extends org.apache.myfaces.webapp.AbstractFacesInitializer
  {
      private static final Logger log = Logger.getLogger(FaceletsInitilializer.class.getName());
  
      @Override
      protected void initContainerIntegration(ServletContext servletContext, ExternalContext externalContext)
      {
          ExpressionFactory expressionFactory = getUserDefinedExpressionFactory(externalContext);
          if (expressionFactory == null)
          {
              String[] candidates = new String[] { "org.apache.el.ExpressionFactoryImpl",
                  "com.sun.el.ExpressionFactoryImpl", "de.odysseus.el.ExpressionFactoryImpl",
                  "org.jboss.el.ExpressionFactoryImpl", "com.caucho.el.ExpressionFactoryImpl" };
              
              for (String candidate : candidates)
              {
                  expressionFactory = loadExpressionFactory(candidate, false);
                  if (expressionFactory != null)
                  {
                      if (log.isLoggable(Level.FINE))
                      {
                          log.fine("javax.el.ExpressionFactory implementation found: " + candidate);
                      }
                      break;
                  }
              }
          }
  
          if (expressionFactory == null)
          {
              throw new FacesException("No javax.el.ExpressionFactory found. Please provide" +
                      " <context-param> in web.xml: org.apache.myfaces.EXPRESSION_FACTORY");
          }
          
          buildConfiguration(servletContext, externalContext, expressionFactory);
      }
  
  }