/*

  * $Source: /usr/cvsroot/melati/melati/src/main/java/org/melati/template/freemarker/FreemarkerTemplateEngine.java,v $

  * $Revision: 1.5 $

  *

  * Copyright (C) 2012 Tim Pizey

  *

  * Part of Melati (http://melati.org), a framework for the rapid

  * development of clean, maintainable web applications.

  *

  * Melati is free software; Permission is granted to copy, distribute

  * and/or modify this software under the terms either:

  *

  * a) the GNU General Public License as published by the Free Software

  *    Foundation; either version 2 of the License, or (at your option)

  *    any later version,

  *

  *    or

  *

  * b) any version of the Melati Software License, as published

  *    at http://melati.org

  *

  * You should have received a copy of the GNU General Public License and

  * the Melati Software License along with this program;

  * if not, write to the Free Software Foundation, Inc.,

  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the

  * GNU General Public License and visit http://melati.org to obtain the

  * Melati Software License.

  *

  * Feel free to contact the Developers of Melati (http://melati.org),

  * if you would like to work out a different arrangement than the options

  * outlined here.  It is our intention to allow Melati to be used by as

  * wide an audience as possible.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  *

  * Contact details for copyright holder:

  *

  *     Tim Pizey <timp At paneris.org>

  */

 package org.melati.template.freemarker;

 import java.io.FileNotFoundException;

 import java.util.HashMap;

 import java.util.Map;

 import org.apache.velocity.exception.ParseErrorException;

 import org.apache.velocity.exception.ResourceNotFoundException;

 import org.melati.poem.AccessPoemException;

 import org.melati.template.AbstractTemplateEngine;

 import org.melati.MelatiConfig;

 import org.melati.template.NotFoundException;

 import org.melati.template.Template;

 import org.melati.template.TemplateContext;

 import org.melati.template.TemplateEngine;

 import org.melati.template.TemplateEngineException;

 import org.melati.template.velocity.VelocityTemplate;

 import org.melati.util.MelatiBugMelatiException;

 import org.melati.util.MelatiStringWriter;

 import org.melati.util.MelatiWriter;

 import freemarker.ext.beans.BeansWrapper;

 import freemarker.template.Configuration;

 //import freemarker.template.DefaultObjectWrapper;

 /**

  * Wrapper for the Freemarker Template Engine for use with Melati.

  * @author timp

  * @since 6 Mar 2012

  *

  */

 public class FreemarkerTemplateEngine extends AbstractTemplateEngine implements TemplateEngine {

   /** The name of the engine. */

   public static final String NAME = "freemarker";

   private Configuration config;

   /**

    * @see org.melati.template.TemplateEngine#init(org.melati.MelatiConfig)

    */

   @Override

   public void init(MelatiConfig melatiConfig) throws TemplateEngineException {

     try {

       config = new Configuration();

       config.setClassForTemplateLoading(this.getClass(), "/"); // note first argument redundant

       BeansWrapper bw = new BeansWrapper();

       bw.setExposureLevel(BeansWrapper.EXPOSE_ALL);

       config.setObjectWrapper(bw);

       //config.setObjectWrapper(new DefaultObjectWrapper());

     } catch (Exception e) {

       throw new TemplateEngineException(e);

     }

   }

   /**

    * @see org.melati.template.TemplateEngine#getTemplateContext()

    */

   @Override

   public TemplateContext getTemplateContext() throws TemplateEngineException {

     Map<String, Object> context = new HashMap<String, Object>();

     return new FreemarkerServletTemplateContext(context);

   }

   /**

    * @see org.melati.template.TemplateEngine#getName()

    */

   @Override

   public String getName() {

     return NAME;

   }

   /**

    * @see org.melati.template.TemplateEngine#templateExtension()

    */

   @Override

   public String templateExtension() {

     return ".fml";

   }

   /**

    * @see org.melati.template.TemplateEngine#template(java.lang.String)

    */

   @Override

   public Template template(String templateName) throws NotFoundException {

     freemarker.template.Template t;

     try {

       t = config.getTemplate(templateName);

       return new FreemarkerTemplate(t);

     } catch (FileNotFoundException e) {

       if (templateName.endsWith(templateExtension())) {

         // have a go at loading the velocity template and converting it, 

         // which may entail its creation from wm

         String velocityTemplateName = templateName.substring(0, templateName

             .lastIndexOf(templateExtension()))

             + ".vm";

         try {

           return new VelocityTemplate(velocityTemplateName);

         } catch (ParseErrorException p) {

           throw new MelatiBugMelatiException(

               "Problem converting a Velocity template to a Freemarker template: " + velocityTemplateName,

               p);

         } catch (ResourceNotFoundException e2) {

             throw new NotFoundException("Could not find template " + templateName + " or " + velocityTemplateName);

         } 

       } else throw new NotFoundException("Could not find template " + templateName, e);

     } catch (Exception e) {

       throw new TemplateEngineException(e);

     }

   }

   /**

    * @see org.melati.template.TemplateEngine#expandTemplate(org.melati.util.MelatiWriter, java.lang.String, org.melati.template.TemplateContext)

    */

   @Override

   public void expandTemplate(MelatiWriter out, String templateName, TemplateContext templateContext) throws NotFoundException {

     expandTemplate(out, template(templateName), templateContext);

   }

   /**

    * Expand a {@link org.melati.template.Template} against the context.

    * 

    * @param out

    *        a {@link MelatiWriter} to output on

    * @param template

    *        the {@link org.melati.template.Template} to expand

    * @param templateContext

    *        the {@link TemplateContext} to expand the template against

    * @see org.melati.template.TemplateEngine#expandTemplate(org.melati.util.MelatiWriter, org.melati.template.Template, org.melati.template.TemplateContext)

    */

   @Override

   public void expandTemplate(MelatiWriter out, Template template, TemplateContext templateContext) {

     try {

       template.write(out, templateContext);

     } catch (TemplateEngineException problem) {

       Exception underlying = problem.subException;

       if (underlying instanceof AccessPoemException) {

         throw (AccessPoemException)underlying;

       }

       throw problem;

     } 

   }

   /**

    * @see org.melati.template.TemplateEngine#expandedTemplate(org.melati.template.Template, org.melati.template.TemplateContext)

    */

   @Override

   public String expandedTemplate(Template template, TemplateContext templateContext) {

     MelatiStringWriter s = new MelatiStringWriter();

     expandTemplate(s, template, templateContext);

     return s.toString();

   }

   /**

    * @see org.melati.template.TemplateEngine#getStringWriter()

    */

   @Override

   public MelatiStringWriter getStringWriter() {

     return new MelatiStringWriter();

   }

   /**

    * Get the underlying engine.

    * Only used by WebMacro, deprecated.

    * 

    * @see org.melati.template.TemplateEngine#getEngine()

    * @return null - for Freemarker we do not expose this

    */

   @Override

   public Object getEngine() {

     return null;

   }

 }