/*
    * $Id$
    *
    * 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.servlet.context;
  
  import java.io.IOException;
  
  import javax.servlet.ServletContext;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.http.HttpServletRequest;
  
  import org.apache.tiles.ArrayStack;
  import org.apache.tiles.TilesApplicationContext;
  import org.apache.tiles.TilesContainer;
  import org.apache.tiles.access.TilesAccess;
  import org.apache.tiles.context.TilesRequestContext;
  import org.apache.tiles.context.TilesRequestContextWrapper;
  import org.apache.tiles.impl.NoSuchContainerException;
  import org.apache.tiles.util.TilesIOException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * Utilities for Tiles servlet support.
   *
   * @version $Rev$ $Date$
   * @since 2.0.6
   */
  public final class ServletUtil {
  
      /**
       * The name of the attribute that will contain the compose stack.
       */
      public static final String COMPOSE_STACK_ATTRIBUTE_NAME = "org.apache.tiles.template.COMPOSE_STACK";
  
      /**
       * Name of the attribute used to store the force-include option.
       * @since 2.0.6
       */
      public static final String FORCE_INCLUDE_ATTRIBUTE_NAME =
          "org.apache.tiles.servlet.context.ServletTilesRequestContext.FORCE_INCLUDE";
  
      /**
       * Name of the attribute used to store the current used container.
       */
      public static final String CURRENT_CONTAINER_ATTRIBUTE_NAME =
          "org.apache.tiles.servlet.context.ServletTilesRequestContext.CURRENT_CONTAINER_KEY";
  
      /**
       * Private constructor to avoid instantiation.
       */
      private ServletUtil() {
      }
  
      /**
       * Returns true if forced include of the result is needed.
       *
       * @param request The HTTP request.
       * @return If <code>true</code> the include operation must be forced.
       * @since 2.0.6
       */
      public static boolean isForceInclude(HttpServletRequest request) {
          Boolean retValue = (Boolean) request
                  .getAttribute(ServletUtil.FORCE_INCLUDE_ATTRIBUTE_NAME);
          return retValue != null && retValue.booleanValue();
      }
  
      /**
       * Sets the option that enables the forced include of the response.
       *
       * @param request The HTTP request.
       * @param forceInclude If <code>true</code> the include operation must be
       * forced.
       * @since 2.0.6
       */
      public static void setForceInclude(HttpServletRequest request,
              boolean forceInclude) {
          Boolean retValue = Boolean.valueOf(forceInclude);
          request.setAttribute(
                 ServletUtil.FORCE_INCLUDE_ATTRIBUTE_NAME,
                 retValue);
     }
 
     /**
      * Returns the default Tiles container.
      *
      * @param context The servlet context to use.
      * @return The default Tiles container.
      * @since 2.1.2
      */
     public static TilesContainer getContainer(ServletContext context) {
         return getContainer(context, TilesAccess.CONTAINER_ATTRIBUTE);
     }
 
     /**
      * Returns a specific Tiles container.
      *
      * @param context The servlet context to use.
      * @param key The key under which the container is stored. If null, the
      * default container will be returned.
      * @return The requested Tiles container.
      * @since 2.1.2
      */
     public static TilesContainer getContainer(ServletContext context, String key) {
         if (key == null) {
             key = TilesAccess.CONTAINER_ATTRIBUTE;
         }
         return (TilesContainer) context.getAttribute(key);
     }
 
     /**
      * Configures the default container to be used in the application.
      *
      * @param context The servlet context object to use.
      * @param container The container object to set.
      * @since 2.1.2
      */
     public static void setContainer(ServletContext context,
             TilesContainer container) {
         setContainer(context, container, TilesAccess.CONTAINER_ATTRIBUTE);
     }
 
     /**
      * Configures the container to be used in the application.
      *
      * @param context The servlet context object to use.
      * @param container The container object to set.
      * @param key The key under which the container will be stored.
      * @since 2.1.2
      */
     public static void setContainer(ServletContext context,
             TilesContainer container, String key) {
         Logger log = LoggerFactory.getLogger(ServletUtil.class);
         if (key == null) {
             key = TilesAccess.CONTAINER_ATTRIBUTE;
         }
 
         if (container == null) {
             if (log.isInfoEnabled()) {
                 log.info("Removing TilesContext for context: " + context.getClass().getName());
             }
             context.removeAttribute(key);
         }
         if (container != null && log.isInfoEnabled()) {
             log.info("Publishing TilesContext for context: " + context.getClass().getName());
         }
         context.setAttribute(key, container);
     }
 
     /**
      * Sets the current container to use in web pages.
      *
      * @param request The request to use.
      * @param context The servlet context to use.
      * @param key The key under which the container is stored.
      * @since 2.1.0
      */
     public static void setCurrentContainer(ServletRequest request,
             ServletContext context, String key) {
         TilesContainer container = getContainer(context, key);
         if (container != null) {
             request.setAttribute(CURRENT_CONTAINER_ATTRIBUTE_NAME, container);
         } else {
             throw new NoSuchContainerException("The container with the key '"
                     + key + "' cannot be found");
         }
     }
 
     /**
      * Sets the current container to use in web pages.
      *
      * @param request The request to use.
      * @param context The servlet context to use.
      * @param container The container to use as the current container.
      * @since 2.1.0
      */
     public static void setCurrentContainer(ServletRequest request,
             ServletContext context, TilesContainer container) {
         if (container != null) {
             request.setAttribute(CURRENT_CONTAINER_ATTRIBUTE_NAME, container);
         } else {
             throw new NoSuchContainerException("The container cannot be null");
         }
     }
 
     /**
      * Returns the current container that has been set, or the default one.
      *
      * @param request The request to use.
      * @param context The servlet context to use.
      * @return The current Tiles container to use in web pages.
      * @since 2.1.0
      */
     public static TilesContainer getCurrentContainer(ServletRequest request,
             ServletContext context) {
         TilesContainer container = (TilesContainer) request
                 .getAttribute(CURRENT_CONTAINER_ATTRIBUTE_NAME);
         if (container == null) {
             container = getContainer(context);
             request.setAttribute(CURRENT_CONTAINER_ATTRIBUTE_NAME, container);
         }
 
         return container;
     }
 
     /**
      * 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.
      * @since 2.1.1
      */
     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 TilesIOException(message, rootCause);
         } else {
             retValue = new TilesIOException(message, ex);
         }
 
         return retValue;
     }
 
     /**
      * Returns the compose stack, that is used by the tags to compose
      * definitions, attributes, etc.
      *
      * @param request The HTTP request.
      * @return The compose stack.
      * @since 2.2.0
      */
     @SuppressWarnings("unchecked")
     public static ArrayStack<Object> getComposeStack(HttpServletRequest request) {
         ArrayStack<Object> composeStack = (ArrayStack<Object>) request.getAttribute(
                 COMPOSE_STACK_ATTRIBUTE_NAME);
         if (composeStack == null) {
             composeStack = new ArrayStack<Object>();
             request.setAttribute(COMPOSE_STACK_ATTRIBUTE_NAME, composeStack);
         }
         return composeStack;
     }
 
     /**
      * 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.
      * @since 2.2.0
      */
     public static ServletTilesRequestContext getServletRequest(TilesRequestContext request) {
         TilesRequestContext currentRequest = request;
         while (true) {
             if (currentRequest == null) {
                 throw new NotAServletEnvironmentException("Last Tiles request context is null");
             }
 
             if (currentRequest instanceof ServletTilesRequestContext) {
                 return (ServletTilesRequestContext) currentRequest;
             }
             if (!(currentRequest instanceof TilesRequestContextWrapper)) {
                 throw new NotAServletEnvironmentException("Not a Servlet environment, not supported");
             }
             currentRequest = ((TilesRequestContextWrapper) 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.
      * @since 2.2.0
      */
     public static ServletContext getServletContext(TilesApplicationContext applicationContext) {
         if (applicationContext instanceof ServletTilesApplicationContext) {
             return (ServletContext) ((ServletTilesApplicationContext) applicationContext).getContext();
         }
 
         throw new NotAServletEnvironmentException("Not a Servlet-based environment");
     }
 }