/*
    * $Id: FreeMarkerUtil.java 797765 2009-07-25 13:20:26Z apetrelli $
    *
    * 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.freemarker.context;
  
  import java.io.IOException;
  import java.io.StringWriter;
  
  import javax.servlet.http.HttpServletRequest;
  
  import org.apache.tiles.ArrayStack;
  import org.apache.tiles.TilesContainer;
  import org.apache.tiles.access.TilesAccess;
  import org.apache.tiles.freemarker.FreeMarkerTilesException;
  import org.apache.tiles.freemarker.io.NullWriter;
  import org.apache.tiles.impl.NoSuchContainerException;
  import org.apache.tiles.servlet.context.ServletUtil;
  
  import freemarker.core.Environment;
  import freemarker.ext.servlet.FreemarkerServlet;
  import freemarker.ext.servlet.HttpRequestHashModel;
  import freemarker.ext.servlet.ServletContextHashModel;
  import freemarker.template.TemplateDirectiveBody;
  import freemarker.template.TemplateException;
  import freemarker.template.TemplateModel;
  import freemarker.template.TemplateModelException;
  import freemarker.template.utility.DeepUnwrap;
  
  /***
   * Utilities for FreeMarker usage in Tiles.
   *
   * @version $Rev: 797765 $ $Date: 2009-07-25 15:20:26 +0200 (sab, 25 lug 2009) $
   * @since 2.2.0
   */
  public final class FreeMarkerUtil {
  
      /***
       * The name of the attribute that holds the compose stack.
       */
      public static final String COMPOSE_STACK_ATTRIBUTE_NAME = "org.apache.tiles.template.COMPOSE_STACK";
  
      /***
       * Private constructor to avoid instantiation.
       */
      private FreeMarkerUtil() {
      }
  
      /***
       * Returns true if forced include of the result is needed.
       *
       * @param env The current FreeMarker environment.
       * @return If <code>true</code> the include operation must be forced.
       * @since 2.2.0
       */
      public static boolean isForceInclude(Environment env) {
          return ServletUtil
                  .isForceInclude(getRequestHashModel(env).getRequest());
      }
  
      /***
       * Sets the option that enables the forced include of the response.
       *
       * @param env The current FreeMarker environment.
       * @param forceInclude If <code>true</code> the include operation must be
       * forced.
       * @since 2.2.0
       */
      public static void setForceInclude(Environment env, boolean forceInclude) {
          ServletUtil.setForceInclude(getRequestHashModel(env).getRequest(),
                  forceInclude);
      }
  
      /***
       * Returns a specific Tiles container.
       *
       * @param env The current FreeMarker environment.
       * @param key The key under which the container is stored. If null, the
       * default container will be returned.
       * @return The requested Tiles container.
       * @since 2.2.0
       */
     public static TilesContainer getContainer(Environment env, String key) {
         if (key == null) {
             key = TilesAccess.CONTAINER_ATTRIBUTE;
         }
         return (TilesContainer) getServletContextHashModel(env).getServlet()
                 .getServletContext().getAttribute(key);
     }
 
     /***
      * Sets the current container to use in web pages.
      *
      * @param env The current FreeMarker environment.
      * @param key The key under which the container is stored.
      * @since 2.2.0
      */
     public static void setCurrentContainer(Environment env, String key) {
         TilesContainer container = getContainer(env, key);
         if (container != null) {
             getRequestHashModel(env).getRequest().setAttribute(
                     ServletUtil.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 env The current FreeMarker environment.
      * @param container The container to use as the current container.
      * @since 2.2.0
      */
     public static void setCurrentContainer(Environment env,
             TilesContainer container) {
         ServletUtil.setCurrentContainer(getRequestHashModel(env).getRequest(),
                 getServletContextHashModel(env).getServlet()
                         .getServletContext(), container);
     }
 
     /***
      * Returns the current container that has been set, or the default one.
      *
      * @param env The current FreeMarker environment.
      * @return The current Tiles container to use in web pages.
      * @since 2.2.0
      */
     public static TilesContainer getCurrentContainer(Environment env) {
         return ServletUtil.getCurrentContainer(getRequestHashModel(env)
                 .getRequest(), getServletContextHashModel(env).getServlet()
                 .getServletContext());
     }
 
     /***
      * Returns the HTTP request hash model.
      *
      * @param env The current FreeMarker environment.
      * @return The request hash model.
      * @since 2.2.0
      */
     public static HttpRequestHashModel getRequestHashModel(Environment env) {
         try {
             return (HttpRequestHashModel) env.getDataModel().get(
                     FreemarkerServlet.KEY_REQUEST);
         } catch (TemplateModelException e) {
             throw new FreeMarkerTilesException(
                     "Exception got when obtaining the request hash model", e);
         }
     }
 
     /***
      * Returns the servlet context hash model.
      *
      * @param env The current FreeMarker environment.
      * @return The servlet context hash model.
      * @since 2.2.0
      */
     public static ServletContextHashModel getServletContextHashModel(
             Environment env) {
         try {
             return (ServletContextHashModel) env.getDataModel().get(
                     FreemarkerServlet.KEY_APPLICATION);
         } catch (TemplateModelException e) {
             throw new FreeMarkerTilesException(
                     "Exception got when obtaining the application hash model",
                     e);
         }
     }
 
     /***
      * Unwraps a TemplateModel to extract a string.
      *
      * @param model The TemplateModel to unwrap.
      * @return The unwrapped string.
      * @since 2.2.0
      */
     public static String getAsString(TemplateModel model) {
         try {
             return (String) DeepUnwrap.unwrap(model);
         } catch (TemplateModelException e) {
             throw new FreeMarkerTilesException("Cannot unwrap a model", e);
         }
     }
 
     /***
      * Unwraps a TemplateModel to extract a boolean.
      *
      * @param model The TemplateModel to unwrap.
      * @param defaultValue If the value is null, this value will be returned.
      * @return The unwrapped boolean.
      * @since 2.2.0
      */
     public static boolean getAsBoolean(TemplateModel model, boolean defaultValue) {
         try {
             Boolean retValue = (Boolean) DeepUnwrap.unwrap(model);
             return retValue != null ? retValue : defaultValue;
         } catch (TemplateModelException e) {
             throw new FreeMarkerTilesException("Cannot unwrap a model", e);
         }
     }
 
     /***
      * Unwraps a TemplateModel to extract an object.
      *
      * @param model The TemplateModel to unwrap.
      * @return The unwrapped object.
      * @since 2.2.0
      */
     public static Object getAsObject(TemplateModel model) {
         try {
             return DeepUnwrap.unwrap(model);
         } catch (TemplateModelException e) {
             throw new FreeMarkerTilesException("Cannot unwrap a model", e);
         }
     }
 
     /***
      * Sets an attribute in the desired scope.
      *
      * @param env The FreeMarker current environment.
      * @param name The name of the attribute.
      * @param obj The value of the attribute.
      * @param scope The scope. It can be <code>page</code>, <code>request</code>
      * , <code>session</code>, <code>application</code>.
      * @since 2.2.0
      */
     public static void setAttribute(Environment env, String name, Object obj,
             String scope) {
         if (scope == null) {
             scope = "page";
         }
         if ("page".equals(scope)) {
             try {
                 TemplateModel model = env.getObjectWrapper().wrap(obj);
                 env.setVariable(name, model);
             } catch (TemplateModelException e) {
                 throw new FreeMarkerTilesException(
                         "Error when wrapping an object", e);
             }
         } else if ("request".equals(scope)) {
             getRequestHashModel(env).getRequest().setAttribute(name, obj);
         } else if ("session".equals(scope)) {
             getRequestHashModel(env).getRequest().getSession().setAttribute(
                     name, obj);
         } else if ("application".equals(scope)) {
             getServletContextHashModel(env).getServlet().getServletContext()
                     .setAttribute(name, obj);
         }
     }
 
     /***
      * Returns the current compose stack, or creates a new one if not present.
      *
      * @param env The current FreeMarker environment.
      * @return The compose stack.
      * @since 2.2.0
      */
     @SuppressWarnings("unchecked")
     public static ArrayStack<Object> getComposeStack(Environment env) {
         HttpServletRequest request = getRequestHashModel(env).getRequest();
         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;
     }
 
     /***
      * Evaluates the body without rendering it.
      *
      * @param body The body to evaluate.
      * @throws TemplateException If something goes wrong during evaluation.
      * @throws IOException If something goes wrong during writing the result.
      * @since 2.2.0
      */
     public static void evaluateBody(TemplateDirectiveBody body)
             throws TemplateException, IOException {
         if (body != null) {
             NullWriter writer = new NullWriter();
             try {
                 body.render(writer);
             } finally {
                 writer.close();
             }
         }
     }
 
     /***
      * Renders the body as a string.
      *
      * @param body The body to render.
      * @return The rendered string.
      * @throws TemplateException If something goes wrong during evaluation.
      * @throws IOException If something goes wrong during writing the result.
      * @since 2.2.0
      */
     public static String renderAsString(TemplateDirectiveBody body)
             throws TemplateException, IOException {
         String bodyString = null;
         if (body != null) {
             StringWriter stringWriter = new StringWriter();
             try {
                 body.render(stringWriter);
             } finally {
                 stringWriter.close();
             }
             bodyString = stringWriter.toString();
         }
         return bodyString;
     }
 }