/*
    * 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 javax.faces.webapp;
  
  import java.io.IOException;
  import java.lang.reflect.Method;
  import java.lang.reflect.InvocationTargetException;
  import java.util.List;
  
  import javax.faces.FactoryFinder;
  import javax.faces.FacesException;
  import javax.faces.context.FacesContext;
  import javax.faces.context.FacesContextFactory;
  import javax.faces.lifecycle.Lifecycle;
  import javax.faces.lifecycle.LifecycleFactory;
  import javax.servlet.Servlet;
  import javax.servlet.ServletConfig;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFWebConfigParam;
  
  /**
   * see Javadoc of <a href="http://java.sun.com/javaee/javaserverfaces/1.2/docs/api/index.html">JSF Specification</a>
   *
   * @author Manfred Geiler (latest modification by $Author: lu4242 $)
   * @version $Revision: 888211 $ $Date: 2009-12-07 20:07:19 -0500 (Mon, 07 Dec 2009) $
   */
  public final class FacesServlet
          implements Servlet
  {
      private static final Log log = LogFactory.getLog(FacesServlet.class);
      
      /**
       * Comma separated list of URIs of (additional) faces config files.
       * (e.g. /WEB-INF/my-config.xml)See JSF 1.0 PRD2, 10.3.2
       * Attention: You do not need to put /WEB-INF/faces-config.xml in here.
       */
      @JSFWebConfigParam(since="1.1")
      public static final String CONFIG_FILES_ATTR = "javax.faces.CONFIG_FILES";
  
      /**
       * Identify the Lifecycle instance to be used.
       */
      @JSFWebConfigParam(since="1.1")
      public static final String LIFECYCLE_ID_ATTR = "javax.faces.LIFECYCLE_ID";
  
      private static final String SERVLET_INFO = "FacesServlet of the MyFaces API implementation";
      
      /**
       * Indicate if myfaces is responsible to handle errors. 
       * See http://wiki.apache.org/myfaces/Handling_Server_Errors for details. 
       */
      @JSFWebConfigParam(defaultValue="true",expectedValues="true,false", since="1.2.4")
      private static final String ERROR_HANDLING_PARAMETER = "org.apache.myfaces.ERROR_HANDLING";
      
      /**
       * If you want to choose a different class for handling the exception.
       * <p> 
       * The error-handler needs to include the following methods:
       * </p>
       * <ul>
       * <li>handleException(FacesContext fc, Exception ex)</li>
       * <li>handleExceptionList(FacesContext facesContext, List exceptionList)</li>
       * <li>handleThrowable(FacesContext facesContext, Throwable ex)</li>
       * </ul>
       */
      @JSFWebConfigParam(since="1.2.4")
      private static final String ERROR_HANDLER_PARAMETER = "org.apache.myfaces.ERROR_HANDLER";
      private static final String ERROR_HANDLING_EXCEPTION_LIST = "org.apache.myfaces.errorHandling.exceptionList";
  
  
      private ServletConfig _servletConfig;
      private FacesContextFactory _facesContextFactory;
      private Lifecycle _lifecycle;
  
      public FacesServlet()
      {
         super();
     }
 
     public void destroy()
     {
         _servletConfig = null;
         _facesContextFactory = null;
         _lifecycle = null;
         if(log.isTraceEnabled()) log.trace("destroy");
     }
 
     public ServletConfig getServletConfig()
     {
         return _servletConfig;
     }
 
     public String getServletInfo()
     {
         return SERVLET_INFO;
     }
 
     private String getLifecycleId()
     {
         //1. check for Servlet's init-param
         //2. check for global context parameter
         //3. use default Lifecycle Id, if none of them was provided
         String serLifecycleId = _servletConfig.getInitParameter(LIFECYCLE_ID_ATTR);
         String appLifecycleId = _servletConfig.getServletContext().getInitParameter(LIFECYCLE_ID_ATTR);
         appLifecycleId = serLifecycleId == null ? appLifecycleId : serLifecycleId;
         return appLifecycleId != null ? appLifecycleId : LifecycleFactory.DEFAULT_LIFECYCLE;
     }
 
     public void init(ServletConfig servletConfig)
             throws ServletException
     {
         if(log.isTraceEnabled()) log.trace("init begin");
         _servletConfig = servletConfig;
         _facesContextFactory = (FacesContextFactory)FactoryFinder.getFactory(FactoryFinder.FACES_CONTEXT_FACTORY);
         //TODO: null-check for Weblogic, that tries to initialize Servlet before ContextListener
 
         //Javadoc says: Lifecycle instance is shared across multiple simultaneous requests, it must be implemented in a thread-safe manner.
         //So we can acquire it here once:
         LifecycleFactory lifecycleFactory = (LifecycleFactory)FactoryFinder.getFactory(FactoryFinder.LIFECYCLE_FACTORY);
         _lifecycle = lifecycleFactory.getLifecycle(getLifecycleId());
         if(log.isTraceEnabled()) log.trace("init end");
     }
 
     public void service(ServletRequest request,
                         ServletResponse response)
             throws IOException,
                    ServletException
     {
 
         HttpServletRequest httpRequest = ((HttpServletRequest) request);
         String pathInfo = httpRequest.getPathInfo();
 
         // if it is a prefix mapping ...
         if (pathInfo != null
                 && (pathInfo.startsWith("/WEB-INF") || pathInfo
                         .startsWith("/META-INF")))
         {
             StringBuffer buffer = new StringBuffer();
 
             buffer.append(" Someone is trying to access a secure resource : ").append(pathInfo);
             buffer.append("\n remote address is ").append(httpRequest.getRemoteAddr());
             buffer.append("\n remote host is ").append(httpRequest.getRemoteHost());
             buffer.append("\n remote user is ").append(httpRequest.getRemoteUser());
             buffer.append("\n request URI is ").append(httpRequest.getRequestURI());
 
             log.warn(buffer.toString());
 
             // Why does RI return a 404 and not a 403, SC_FORBIDDEN ?
 
             ((HttpServletResponse) response)
                     .sendError(HttpServletResponse.SC_NOT_FOUND);
             return;
         }
 
         if(log.isTraceEnabled()) log.trace("service begin");
 
         FacesContext facesContext = prepareFacesContext(request, response);
 
         try {
             _lifecycle.execute(facesContext);
 
             if (!handleQueuedExceptions(facesContext))
             {
                 _lifecycle.render(facesContext);
             }
         }
         catch (Exception e)
         {
             handleLifecycleException(facesContext, e);
         }
         catch (Throwable e)
         {
             handleLifecycleThrowable(facesContext, e);
         }
         finally
         {
             facesContext.release();
         }
         if(log.isTraceEnabled()) log.trace("service end");
     }
 
     /**This method makes sure we see an exception page also
      * if an exception has been thrown in UIInput.updateModel();
      * In this method, according to the spec, we may not rethrow the
      * exception, so we add it to a list and process it here.
      *
      * Attention: if you use redirects, the exceptions will get lost - exactly
      * like in the case of FacesMessages. If you want them to be taken over to the
      * next request, you should try the redirect-tracker of MyFaces.
      *
      * @param facesContext
      * @throws FacesException
      */
     private boolean handleQueuedExceptions(FacesContext facesContext) throws IOException, ServletException {
         List li = (List)
                 facesContext.getExternalContext().getRequestMap().get(ERROR_HANDLING_EXCEPTION_LIST);
 
         if(li != null && li.size()>=1)  {
             //todo: for now, we only handle the first exception out of the list - we just rethrow this
             //first exception.
             //in the end, we should enable the error handler to show all the exceptions at once
             boolean errorHandling = getBooleanValue(facesContext.getExternalContext().getInitParameter(ERROR_HANDLING_PARAMETER), true);
 
             if(errorHandling) {
                 String errorHandlerClass = facesContext.getExternalContext().getInitParameter(ERROR_HANDLER_PARAMETER);            
                 if(errorHandlerClass != null) {
                     try {
                         Class clazz = Class.forName(errorHandlerClass);
 
                         Object errorHandler = clazz.newInstance();
 
                         Method m = clazz.getMethod("handleExceptionList", new Class[]{FacesContext.class,List.class});
                         m.invoke(errorHandler, new Object[]{facesContext, li});
                     }
                     catch(ClassNotFoundException ex) {
                         throw new ServletException("Error-Handler : " +errorHandlerClass+ " was not found. Fix your web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                     } catch (IllegalAccessException ex) {
                         throw new ServletException("Constructor of error-Handler : " +errorHandlerClass+ " is not accessible. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                     } catch (InstantiationException ex) {
                         throw new ServletException("Error-Handler : " +errorHandlerClass+ " could not be instantiated. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                     } catch (NoSuchMethodException ex) {
                         //Handle in the old way, since no custom method handleExceptionList found,
                         //throwing the first FacesException on the list.
                         throw (FacesException) li.get(0);
                     } catch (InvocationTargetException ex) {
                         throw new ServletException("Excecution of method handleException in Error-Handler : " +errorHandlerClass+ " threw an exception. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                     }
                 }
                 else {
                     _ErrorPageWriter.handleExceptionList(facesContext, li);
                 }
             }
             else {
                 _ErrorPageWriter.throwException((Exception) li.get(0));
             }
             return true;
         }
         return false;
     }
 
     private void handleLifecycleException(FacesContext facesContext, Exception e) throws IOException, ServletException {
 
         boolean errorHandling = getBooleanValue(facesContext.getExternalContext().getInitParameter(ERROR_HANDLING_PARAMETER), true);
 
         if(errorHandling) {
             String errorHandlerClass = facesContext.getExternalContext().getInitParameter(ERROR_HANDLER_PARAMETER);
             if(errorHandlerClass != null) {
                 try {
                     Class clazz = Class.forName(errorHandlerClass);
 
                     Object errorHandler = clazz.newInstance();
 
                     Method m = clazz.getMethod("handleException", new Class[]{FacesContext.class,Exception.class});
                     m.invoke(errorHandler, new Object[]{facesContext, e});
                 }
                 catch(ClassNotFoundException ex) {
                     throw new ServletException("Error-Handler : " +errorHandlerClass+ " was not found. Fix your web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 } catch (IllegalAccessException ex) {
                     throw new ServletException("Constructor of error-Handler : " +errorHandlerClass+ " is not accessible. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 } catch (InstantiationException ex) {
                     throw new ServletException("Error-Handler : " +errorHandlerClass+ " could not be instantiated. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 } catch (NoSuchMethodException ex) {
                     log.error("Error-Handler : " +errorHandlerClass+ " did not have a method with name : handleException and parameters : javax.faces.context.FacesContext, java.lang.Exception. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                     //Try to look if it is implemented more general method handleThrowable
                     handleLifecycleThrowable(facesContext, e);
                 } catch (InvocationTargetException ex) {
                     throw new ServletException("Excecution of method handleException in Error-Handler : " +errorHandlerClass+ " caused an exception. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 }
             }
             else {
                 _ErrorPageWriter.handleException(facesContext, e);
             }
         }
         else {
             _ErrorPageWriter.throwException(e);
         }
     }
     
     private void handleLifecycleThrowable(FacesContext facesContext, Throwable e) throws IOException, ServletException {
 
         boolean errorHandling = getBooleanValue(facesContext.getExternalContext().getInitParameter(ERROR_HANDLING_PARAMETER), true);
 
         if(errorHandling) {
             String errorHandlerClass = facesContext.getExternalContext().getInitParameter(ERROR_HANDLER_PARAMETER);            
             if(errorHandlerClass != null) {
                 try {
                     Class clazz = Class.forName(errorHandlerClass);
 
                     Object errorHandler = clazz.newInstance();
 
                     Method m = clazz.getMethod("handleThrowable", new Class[]{FacesContext.class,Throwable.class});
                     m.invoke(errorHandler, new Object[]{facesContext, e});
                 }
                 catch(ClassNotFoundException ex) {
                     throw new ServletException("Error-Handler : " +errorHandlerClass+ " was not found. Fix your web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 } catch (IllegalAccessException ex) {
                     throw new ServletException("Constructor of error-Handler : " +errorHandlerClass+ " is not accessible. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 } catch (InstantiationException ex) {
                     throw new ServletException("Error-Handler : " +errorHandlerClass+ " could not be instantiated. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 } catch (NoSuchMethodException ex) {
                     throw new ServletException("Error-Handler : " +errorHandlerClass+ " did not have a method with name : handleException and parameters : javax.faces.context.FacesContext, java.lang.Exception. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 } catch (InvocationTargetException ex) {
                     throw new ServletException("Excecution of method handleException in Error-Handler : " +errorHandlerClass+ " threw an exception. Error-Handler is specified in web.xml-parameter : "+ERROR_HANDLER_PARAMETER,ex);
                 }
             }
             else {
                 _ErrorPageWriter.handleThrowable(facesContext, e);
             }
         }
         else {
             _ErrorPageWriter.throwException(e);
         }
     }
 
     private static boolean getBooleanValue(String initParameter, boolean defaultVal) {
 
         if(initParameter == null || initParameter.trim().length()==0)
             return defaultVal;
 
         return (initParameter.equalsIgnoreCase("on") || initParameter.equals("1") || initParameter.equalsIgnoreCase("true"));
     }
 
     private FacesContext prepareFacesContext(ServletRequest request, ServletResponse response) {
         FacesContext facesContext
                 = _facesContextFactory.getFacesContext(_servletConfig.getServletContext(),
                                                        request,
                                                        response,
                                                        _lifecycle);
         return facesContext;
     }
 }