package org.apache.turbine.modules.screens;

 /*

  * 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 org.apache.commons.lang.StringUtils;

 import org.apache.commons.lang.exception.ExceptionUtils;

 import org.apache.turbine.TurbineConstants;

 import org.apache.turbine.pipeline.PipelineData;

 import org.apache.turbine.util.RunData;

 import org.apache.velocity.context.Context;

 /**

  * VelocityCachedScreen is Turbine 2.3.3 VelocityDirectScreen (same package)

  * with methods added for {@link PipelineData}.

  * It is is a screen class which buffers its output

  * before flushing the output stream. It is used in Jetspeed-1 portal.

  * <p>

  * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>

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

  * @version $Id$

  */

 public class VelocityCachedScreen

     extends VelocityScreen

 {

     /** The prefix for lookup up screen pages */

     private String prefix = getPrefix() + "/";

     /**

      * This builds the Velocity template.

      *

      * @param pipelineData Turbine information.

      * @return A ConcreteElement.

      * @throws Exception a generic exception.

      */

     @Override

     public String buildTemplate(PipelineData pipelineData)

         throws Exception

     {

         RunData data = getRunData(pipelineData);

         Context context = velocity.getContext(pipelineData);

         String screenTemplate = data.getTemplateInfo().getScreenTemplate();

         String templateName

             = templateService.getScreenTemplateName(screenTemplate);

         // The Template Service could not find the Screen

         if (StringUtils.isEmpty(templateName))

         {

             log.error("Screen " + screenTemplate + " not found!");

             throw new Exception("Could not find screen for " + screenTemplate);

         }

         try

         {

             velocity.handleRequest(context, prefix + templateName, data.getOut());

         }

         catch (Exception e)

         {

             // If there is an error, build a $processingException and

             // attempt to call the error.vm template in the screens

             // directory.

             context.put (TurbineConstants.PROCESSING_EXCEPTION_PLACEHOLDER, e.toString());

             context.put (TurbineConstants.STACK_TRACE_PLACEHOLDER, ExceptionUtils.getStackTrace(e));

             velocity.handleRequest(context, prefix + templateError, data.getOut());

         }

         return null;

     }

 }