package org.apache.turbine.services.jsp;

 /*

  * 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.

  */

 import java.io.File;

 import java.io.IOException;

 import javax.servlet.RequestDispatcher;

 import javax.servlet.http.HttpServletRequest;

 import org.apache.commons.configuration.Configuration;

 import org.apache.commons.lang.StringUtils;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.apache.turbine.Turbine;

 import org.apache.turbine.pipeline.PipelineData;

 import org.apache.turbine.services.InitializationException;

 import org.apache.turbine.services.pull.ApplicationTool;

 import org.apache.turbine.services.pull.tools.TemplateLink;

 import org.apache.turbine.services.template.BaseTemplateEngineService;

 import org.apache.turbine.util.RunData;

 import org.apache.turbine.util.TurbineException;

 /**

  * This is a Service that can process JSP templates from within a Turbine

  * screen.

  *

  * @author <a href="mailto:john.mcnally@clearink.com">John D. McNally</a>

  * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>

  * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>

  * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>

  */

 public class TurbineJspService

         extends BaseTemplateEngineService

         implements JspService

 {

     /** The base path[s] prepended to filenames given in arguments */

     private String[] templatePaths;

     /** The relative path[s] prepended to filenames */

     private String[] relativeTemplatePaths;

     /** The buffer size for the output stream. */

     private int bufferSize;

     /** Logging */

     private static Log log = LogFactory.getLog(TurbineJspService.class);

     /**

      * Load all configured components and initialize them. This is

      * a zero parameter variant which queries the Turbine Servlet

      * for its config.

      *

      * @throws InitializationException Something went wrong in the init

      *         stage

      */

     @Override

     public void init()

         throws InitializationException

     {

         try

         {

             initJsp();

             registerConfiguration(JspService.JSP_EXTENSION);

             setInit(true);

         }

         catch (Exception e)

         {

             throw new InitializationException(

                 "TurbineJspService failed to initialize", e);

         }

     }

     /**

      * Adds some convenience objects to the request.  For example an instance

      * of TemplateLink which can be used to generate links to other templates.

      *

      * @param pipelineData the Turbine PipelineData object

      */

     @Override

     public void addDefaultObjects(PipelineData pipelineData)

     {

         HttpServletRequest req = pipelineData.get(Turbine.class, HttpServletRequest.class);

         //

         // This is a place where an Application Pull Tool is used

         // in a regular Java Context. We have no Pull Service with the

         // Jsp Paging stuff, but we can run our Application Tool by Hand:

         //

         ApplicationTool templateLink = new TemplateLink();

         templateLink.init(pipelineData);

         req.setAttribute(LINK, templateLink);

         req.setAttribute(PIPELINE_DATA, pipelineData);

     }

     /**

      * Returns the default buffer size of the JspService

      *

      * @return The default buffer size.

      */

     @Override

     public int getDefaultBufferSize()

     {

         return bufferSize;

     }

     /**

      * executes the JSP given by templateName.

      *

      * @param pipelineData A PipelineData Object

      * @param templateName The template to execute

      * @param isForward whether to perform a forward or include.

      *

      * @throws TurbineException If a problem occurred while executing the JSP

      */

     @Override

     public void handleRequest(PipelineData pipelineData, String templateName, boolean isForward)

         throws TurbineException

     {

         if(!(pipelineData instanceof RunData))

         {

             throw new RuntimeException("Can't cast to rundata from pipeline data.");

         }

         RunData data = (RunData)pipelineData;

         /** template name with relative path */

         String relativeTemplateName = getRelativeTemplateName(templateName);

         if (StringUtils.isEmpty(relativeTemplateName))

         {

             throw new TurbineException(

                 "Template " + templateName + " not found in template paths");

         }

         // get the RequestDispatcher for the JSP

         RequestDispatcher dispatcher = data.getServletContext()

             .getRequestDispatcher(relativeTemplateName);

         try

         {

             if (isForward)

             {

                 // forward the request to the JSP

                 dispatcher.forward(data.getRequest(), data.getResponse());

             }

             else

             {

                 data.getResponse().getWriter().flush();

                 // include the JSP

                 dispatcher.include(data.getRequest(), data.getResponse());

             }

         }

         catch (Exception e)

         {

             // Let's try hard to send the error message to the browser, to speed up debugging

             try

             {

                 data.getResponse().getWriter().print("Error encountered processing a template: "

                     + templateName);

                 e.printStackTrace(data.getResponse().getWriter());

             }

             catch (IOException ignored)

             {

                 // ignore

             }

             // pass the exception to the caller according to the general

             // contract for templating services in Turbine

             throw new TurbineException(

                 "Error encountered processing a template: " + templateName, e);

         }

     }

     /**

      * executes the JSP given by templateName.

      *

      * @param pipelineData A PipelineData Object

      * @param templateName The template to execute

      *

      * @throws TurbineException If a problem occurred while executing the JSP

      */

     @Override

     public void handleRequest(PipelineData pipelineData, String templateName)

         throws TurbineException

     {

         handleRequest(pipelineData, templateName, false);

     }

     /**

      * This method sets up the template cache.

      */

     private void initJsp()

         throws Exception

     {

         Configuration config = getConfiguration();

         // Set relative paths from config.

         // Needed for javax.servlet.RequestDispatcher

         relativeTemplatePaths = config.getStringArray(TEMPLATE_PATH_KEY);

         // Use Turbine Servlet to translate the template paths.

         templatePaths = new String [relativeTemplatePaths.length];

         for (int i=0; i < relativeTemplatePaths.length; i++)

         {

             relativeTemplatePaths[i] = warnAbsolute(relativeTemplatePaths[i]);

             templatePaths[i] = Turbine.getRealPath(relativeTemplatePaths[i]);

         }

         bufferSize = config.getInt(JspService.BUFFER_SIZE_KEY,

             JspService.BUFFER_SIZE_DEFAULT);

     }

     /**

      * Determine whether a given template is available on the

      * configured template pathes.

      *

      * @param template The name of the requested Template

      * @return True if the template is available.

      */

     @Override

     public boolean templateExists(String template)

     {

         for (int i = 0; i < templatePaths.length; i++)

         {

             if (templateExists(templatePaths[i], template))

             {

                 return true;

             }

         }

         return false;

     }

     /**

      * Determine whether a given template exists on the supplied

      * template path. This service ATM only supports file based

      * templates so it simply checks for file existence.

      *

      * @param path The absolute (file system) template path

      * @param template The name of the requested Template

      * @return True if the template is available.

      */

     private boolean templateExists(String path, String template)

     {

         return new File(path, template).exists();

     }

     /**

      * Searches for a template in the default.template path[s] and

      * returns the template name with a relative path which is

      * required by <a href="http://java.sun.com/products/servlet/2.3/javadoc/javax/servlet/ServletContext.html#getRequestDispatcher(java.lang.String)">

      * javax.servlet.RequestDispatcher</a>

      *

      * @param template the name of the template

      * @return String

      */

     @Override

     public String getRelativeTemplateName(String template)

     {

         template = warnAbsolute(template);

         // Find which template path the template is in

         // We have a 1:1 match between relative and absolute

         // pathes so we can use the index for translation.

         for (int i = 0; i < templatePaths.length; i++)

         {

             if (templateExists(templatePaths[i], template))

             {

                 return relativeTemplatePaths[i] + "/" + template;

             }

         }

         return null;

     }

     /**

      * Warn if a template name or path starts with "/".

      *

      * @param template The template to test

      * @return The template name with a leading / stripped off

      */

     private String warnAbsolute(String template)

     {

         if (template.startsWith("/"))

         {

             log.warn("Template " + template

                 + " has a leading /, which is wrong!");

             return template.substring(1);

         }

         return template;

     }

 }