/*

  * $Id: ServletUtil.java 1375743 2012-08-21 20:05:58Z nlebas $

  *

  * 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.tiles.request.servlet;

 import java.io.IOException;

 import javax.servlet.ServletContext;

 import javax.servlet.ServletException;

 import org.apache.tiles.request.ApplicationContext;

 import org.apache.tiles.request.ApplicationAccess;

 import org.apache.tiles.request.RequestWrapper;

 import org.apache.tiles.request.Request;

 /**

  * Utilities for Tiles request servlet support.

  *

  * @version $Rev: 1375743 $ $Date: 2012-08-22 06:05:58 +1000 (Wed, 22 Aug 2012) $

  */

 public final class ServletUtil {

     /**

      * Constructor.

      */

     private ServletUtil() {

     }

     /**

      * Wraps a ServletException to create an IOException with the root cause if present.

      *

      * @param ex The exception to wrap.

      * @param message The message of the exception.

      * @return The wrapped exception.

      */

     public static IOException wrapServletException(ServletException ex,

             String message) {

         IOException retValue;

         Throwable rootCause = ex.getRootCause();

         if (rootCause != null) {

             // Replace the ServletException with an IOException, with the root

             // cause of the first as the cause of the latter.

             retValue = new IOException(message, rootCause);

         } else {

             retValue = new IOException(message, ex);

         }

         return retValue;

     }

     /**

      * Returns the application context getting it from the servlet context. It must be

      * first saved creating a {@link ServletApplicationContext} and using

      * {@link ApplicationAccess#register(ApplicationContext)}.

      *

      * @param servletContext The servlet context.

      * @return The application context, if found, <code>null</code> otherwise.

      */

     public static ApplicationContext getApplicationContext(ServletContext servletContext) {

         return (ApplicationContext) servletContext

                 .getAttribute(ApplicationAccess.APPLICATION_CONTEXT_ATTRIBUTE);

     }

     /**

      * Opens a TilesRequestContext until it finds a ServletTilesRequestContext.

      *

      * @param request The request to open.

      * @return The servlet-based request context.

      * @throws NotAServletEnvironmentException If a servlet-based request

      * context could not be found.

      */

     public static ServletRequest getServletRequest(Request request) {

         Request currentRequest = request;

         while (true) {

             if (currentRequest == null) {

                 throw new NotAServletEnvironmentException("Last Tiles request context is null");

             }

             if (currentRequest instanceof ServletRequest) {

                 return (ServletRequest) currentRequest;

             }

             if (!(currentRequest instanceof RequestWrapper)) {

                 throw new NotAServletEnvironmentException("Not a Servlet environment, not supported");

             }

             currentRequest = ((RequestWrapper) currentRequest).getWrappedRequest();

         }

     }

     /**

      * Gets a servlet context from a TilesApplicationContext.

      *

      * @param applicationContext The application context to analyze.

      * @return The servlet context.

      * @throws NotAServletEnvironmentException If the application context is not

      * servlet-based.

      */

     public static ServletContext getServletContext(ApplicationContext applicationContext) {

         if (applicationContext instanceof ServletApplicationContext) {

             return (ServletContext) ((ServletApplicationContext) applicationContext).getContext();

         }

         throw new NotAServletEnvironmentException("Not a Servlet-based environment");

     }

 }