/*

  * $Source$

  * $Revision$

  *

  * Copyright (C) 2000 Tim Joyce

  *

  * 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 Joyce <timj At paneris.org>

  *     http://paneris.org/

  *     68 Sandbanks Rd, Poole, Dorset. BH14 8BY. UK

  */

 package org.melati.template;

 import java.io.IOException;

 import java.io.PrintWriter;

 import javax.servlet.http.HttpServletResponse;

 import javax.servlet.http.HttpServlet;

 import org.melati.Melati;

 import org.melati.MelatiConfig;

 import org.melati.util.MelatiIOException;

 import org.melati.util.MelatiWriter;

 import org.melati.util.MelatiSimpleWriter;

 import org.melati.util.MelatiStringWriter;

 import org.melati.util.MelatiBufferedWriter;

 /**

  * The <code>null</code> {@link ServletTemplateEngine}.

  *

  * @author Tim Joyce

  */

 public class NoTemplateEngine extends AbstractTemplateEngine implements ServletTemplateEngine {

   private String message =

       "No Template engine is Configured, please specify an engine in " +

       "org.melati.MelatiConfig.properties";

   /**

    * Constructor.

    */

   public NoTemplateEngine() {

     super();

   }

   /**

    * Construct a null Engine.

    *

    * @param config a {@link MelatiConfig}

    */

   public void init(MelatiConfig config) {

     // we don't throw an exception here as it gets hidden away, rather

     // it is better to wait until expandTemplate or getParameters, as

     // that produces a nice

     // exception to the browser

   }

   /**

    * Construct a new Engine for use in a servlet environment.

    *

    * @see org.melati.servlet.TemplateServlet

    * @param melatiConfig a {@link MelatiConfig}

    * @param servlet the servlet we are within

    * @throws TemplateEngineException if any problem occurs with the engine

    */

   public void init(MelatiConfig melatiConfig, HttpServlet servlet) 

       throws TemplateEngineException {

     init(melatiConfig);

   }

   /**

    * Throw exception.

    *

    * @throws TemplateEngineException if any problem occurs with the engine

    * @return a {@link TemplateContext}

    */

   public TemplateContext getTemplateContext()

       throws TemplateEngineException {

     throw new TemplateEngineException(message);

   }

   /**

    * Throw exception.

    *

    * @param melati the {@link Melati}

    * @throws TemplateEngineException always

    * @return an exception

    */

   public ServletTemplateContext getServletTemplateContext(Melati melati)

       throws TemplateEngineException {

     throw new TemplateEngineException(message);

   }

   /**

    * The name of the template engine (used to find the templets).

    * @return the name of the current configured template engine

    */

   public String getName() {

     return "none";

   }

   /**

    * @return the extension of the templates used by this template engine

    */

   public String templateExtension() {

     return ".none";

   }

   /** 

    * Get a template given its name.

    * 

    * @param templateName the name of the template to find

    * @return a template

    */

   public Template template(String templateName) {

     throw new TemplateEngineException(

         "The template " +

         templateName + " could not be found because you have not configured a template engine.");

   }

   /** 

    * Expand the Template against the context.

    *

    * @param out             a {@link MelatiWriter} to output on

    * @param templateName    the name of the template to expand

    * @param templateContext the {@link ServletTemplateContext} to expand 

    *                        the template against

    * @throws TemplateEngineException if invoked

    */

   public void expandTemplate(MelatiWriter out, String templateName,

                              TemplateContext templateContext)

       throws TemplateEngineException {

     throw new TemplateEngineException(message);

   }

   /** 

    * Expand the Template against the context.

    *

    * @param out             a {@link MelatiWriter} to output on

    * @param melatiTemplate  the {@link Template} to expand

    * @param templateContext the {@link ServletTemplateContext} to expand 

    *                        the template against

    * @throws TemplateEngineException if invoked

    */

   public void expandTemplate(MelatiWriter out, Template melatiTemplate,

                              TemplateContext templateContext)

       throws TemplateEngineException {

     throw new TemplateEngineException(message);

   }

   /** 

    * Expand the Template against the context.

    *

    * @param melatiTemplate  the {@link Template} to expand

    * @param templateContext the {@link ServletTemplateContext} to expand 

    *                        the template against

    * @throws TemplateEngineException if invoked

    * {@inheritDoc}

    * @see org.melati.template.TemplateEngine#expandedTemplate

    * (org.melati.template.Template, org.melati.template.TemplateContext)

    */

   public String expandedTemplate(Template melatiTemplate,

                                  TemplateContext templateContext)

       throws TemplateEngineException {

     throw new TemplateEngineException(message);

   }

   /** 

    * @param response the <code>HttpServletResponse</code> that this 

    *                 writer will be part of

    * @param buffered whether the writer should be buffered

    * @return a {@link MelatiWriter} 

    *         appropriate for this engine.

    */

   public MelatiWriter getServletWriter(HttpServletResponse response, 

                                        boolean buffered) {

     PrintWriter printWriter = null;

     try { 

       printWriter = response.getWriter(); 

     } catch (IOException e) { 

       throw new MelatiIOException(e);

     }

     if (buffered)

       return new MelatiBufferedWriter(printWriter);

     else

       return new MelatiSimpleWriter(printWriter);

   }

   /** 

    * Return a {@link MelatiStringWriter}.

    * {@inheritDoc}

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

    * @see Melati#getStringWriter() 

    */

   public MelatiStringWriter getStringWriter() {

     return new MelatiStringWriter();

   }

   /** 

    * Get the underlying engine.

    *

    * @return 'none'

    */

   public Object getEngine() {

     return "none";

   }

 }