/*
    * 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.Iterator;
  
  import javax.el.ExpressionFactory;
  import javax.faces.FactoryFinder;
  import javax.faces.context.ExternalContext;
  import javax.faces.event.PhaseListener;
  import javax.faces.lifecycle.LifecycleFactory;
  import javax.servlet.ServletContext;
  import javax.servlet.jsp.JspApplicationContext;
  import javax.servlet.jsp.JspFactory;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.myfaces.config.RuntimeConfig;
  import org.apache.myfaces.el.ResolverForJSPInitializer;
  import org.apache.myfaces.el.unified.ELResolverBuilder;
  import org.apache.myfaces.el.unified.ResolverBuilderForJSP;
  import org.apache.myfaces.el.unified.resolver.FacesCompositeELResolver;
  import org.apache.myfaces.el.unified.resolver.FacesCompositeELResolver.Scope;
  
  /**
   * Initializes MyFaces in a JSP 2.1 environment.
   *
   */
  public class Jsp21FacesInitializer extends AbstractFacesInitializer
  {
      /**
       * The logger instance for this class.
       */
      private static final Log log = LogFactory.getLog(Jsp21FacesInitializer.class);
      
      /**
       * Cached instance of the JspFactory to use.
       */
      private JspFactory jspFactory;
      
      @Override
      protected void initContainerIntegration(
              ServletContext servletContext, ExternalContext externalContext)
      {
          JspApplicationContext appCtx = 
              getJspFactory().getJspApplicationContext(servletContext);
          appCtx.addELContextListener(new FacesELContextListener());
          
          // check for user-specified ExpressionFactory
          ExpressionFactory expressionFactory = getUserDefinedExpressionFactory(externalContext);
          if (expressionFactory == null)
          {
              expressionFactory = appCtx.getExpressionFactory();
          }
  
          RuntimeConfig runtimeConfig =
              buildConfiguration(servletContext, externalContext, expressionFactory);
          
          // configure the el resolver for jsp
          configureResolverForJSP(appCtx, runtimeConfig);
      }
      
      protected JspFactory getJspFactory()
      {
          if (jspFactory == null) {
              // TODO: this Class.forName will be removed when Tomcat fixes a bug
              // also, we should then be able to remove jasper.jar from the deployment
              try {
                  Class.forName("org.apache.jasper.compiler.JspRuntimeContext");
              } catch (ClassNotFoundException e) {
                  ; // ignore
              } catch (Exception ex) {
                  log.debug("An unexpected exception occured "
                          + "while loading the JspRuntimeContext.", ex);
              }
  
              jspFactory = JspFactory.getDefaultFactory();
          }
  
          return jspFactory;
      }
  
      /**
      * Sets the JspFactory to use. Currently, this method just simplifies
      * testing.
      * 
      * @param jspFactory
      *            the JspFactory to use
      */
     protected void setJspFactory(JspFactory jspFactory)
     {
         this.jspFactory = jspFactory;
     }
 
     /**
      * Register a phase listener to every lifecycle. This listener will lazy fill the el resolver for jsp as soon as the
      * first lifecycle is executed. This is necessarry to allow a faces application further setup after MyFaces has been
      * initialized. When the first request is processed no further configuation of the el resolvers is allowed.
      * 
      * @param appCtx
      * @param runtimeConfig
      */
     private void configureResolverForJSP(JspApplicationContext appCtx, RuntimeConfig runtimeConfig)
     {
         FacesCompositeELResolver facesCompositeELResolver = new FacesCompositeELResolver(Scope.JSP);
         appCtx.addELResolver(facesCompositeELResolver);
         PhaseListener resolverForJSPInitializer = new ResolverForJSPInitializer(
                 createResolverBuilderForJSP(runtimeConfig), facesCompositeELResolver);
 
         LifecycleFactory factory = (LifecycleFactory) FactoryFinder.getFactory(FactoryFinder.LIFECYCLE_FACTORY);
         for (Iterator<String> iter = factory.getLifecycleIds(); iter.hasNext();)
         {
             factory.getLifecycle(iter.next()).addPhaseListener(resolverForJSPInitializer);
         }
     }
     
     protected ELResolverBuilder createResolverBuilderForJSP(RuntimeConfig runtimeConfig)
     {
         return new ResolverBuilderForJSP(runtimeConfig);
     }
 }