/**
    * This file Copyright (c) 2003-2011 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.module.templating.renderers;
  
  import info.magnolia.cms.core.Content;
  import info.magnolia.context.MgnlContext;
  import info.magnolia.module.templating.Template;
  import info.magnolia.module.templating.RenderableDefinition;
  import info.magnolia.module.templating.RenderException;
  import info.magnolia.objectfactory.Classes;
  import info.magnolia.objectfactory.MgnlInstantiationException;
  import org.apache.commons.lang.StringUtils;
  
  import javax.servlet.ServletException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  import java.io.Writer;
  import java.util.Map;
  
  
  /**
   * <p>
   * Servlet template renderer, mapped to template type <code>servlet</code>. Servlet templates can have a
   * <code>path</code> parameter like the jsp ones (request is forwarded to the specified path), or a
   * <code>className</code> parameter.
   * </p>
   * <p>
   * If <code>className</code> is set the servlet class will be instantiated and service() will be called (note the
   * servlet will not properly be loaded by the container in this case, so don't rely on other methods except for
   * doGet()/doPost() being called).
   * </p>
   *
   * @author Fabrizio Giustina
   * @version $Revision: 41137 $ ($Author: gjoseph $)
   */
  public class ServletTemplateRenderer extends AbstractTemplateRenderer {
      private final static org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(ServletTemplateRenderer.class);
  
      public void renderTemplate(Content content, Template template, Writer out) throws IOException, RenderException {
          final HttpServletRequest request = MgnlContext.getWebContext("ServletTemplateRenderer can only be used with a WebContext").getRequest();
          final HttpServletResponse response = MgnlContext.getWebContext("ServletTemplateRenderer can only be used with a WebContext").getResponse();
          final String className = template.getParameter("className");
  
          if (StringUtils.isEmpty(className)) {
              // className not set, simply use path and forward this request
              final String path = template.getTemplatePath();
              if (StringUtils.isEmpty(path)) {
                  throw new IllegalStateException("path or className is missing for servlet template " + template.getName() + ", returning a 404 error");
              }
  
              if (response.isCommitted()) {
                  log.warn("Forwarding to {} for request {}, but response is already committed.", path, request.getRequestURL());
              }
  
              // we can't do an include() because the called template might want to set cookies or call response.sendRedirect()
              try {
                  request.getRequestDispatcher(path).forward(request, response);
              } catch (ServletException e) {
                  throw new RenderException(e);
              }
          } else {
              // use className
              try {
                  final HttpServlet servlet = Classes.newInstance(className);
                  servlet.service(request, response);
              } catch (ServletException e) {
                 throw new RenderException(e);
             } catch (MgnlInstantiationException e) {
                 throw new RenderException(e);
             } catch (ClassNotFoundException e) {
                 throw new RenderException(e);
             }
         }
     }
 
     protected Map newContext() {
         throw new IllegalStateException();
     }
 
     protected void onRender(Content content, RenderableDefinition definition, Writer out, Map ctx, String templatePath) throws RenderException {
         throw new IllegalStateException();
     }
 
 }