/**

  * Copyright 2009 Martin Vysny.

  *

  * This file is part of WebVM.

  *

  * WebVM is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, either version 3 of the License, or

  * (at your option) any later version.

  *

  * WebVM 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.

  *

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

  * along with WebVM.  If not, see <http://www.gnu.org/licenses/>.

  */

 package sk.baka.webvm.rss;

 import sk.baka.webvm.analyzer.ProblemReport;

 import java.io.IOException;

 import java.io.PrintWriter;

 import java.util.Date;

 import java.util.List;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import sk.baka.webvm.WicketApplication;

 /**

  * Provides a RSS feed with the "Problems" report.

  * @author Martin Vysny

  */

 public final class RssFeed extends HttpServlet {

     private static final long serialVersionUID = 1L;

     /** 

      * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.

      * @param request servlet request

      * @param response servlet response

      * @throws ServletException if a servlet-specific error occurs

      * @throws IOException if an I/O error occurs

      */

     protected void processRequest(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         final String contextRoot = getContextRoot(request);

         final String link;

         if (contextRoot != null) {

             link = contextRoot + "/a/Problems";

         } else {

             link = "a/Problems";

         }

         response.setContentType("application/rss+xml");

         PrintWriter out = response.getWriter();

         try {

             out.println("<?xml version=\"1.0\"?>\n<rss version=\"2.0\">");

             out.println("  <channel>\n    <title>WebVM feeds</title>\n    <link>");

             out.println(link);

             out.println("</link>\n    <description>WebVM: Remote server problems</description>");

             out.println("    <language>en-us</language>\n    <ttl>1</ttl>\n");

             final List<List<ProblemReport>> ph = WicketApplication.getHistory().getProblemHistory();

             for (final List<ProblemReport> problems : ph) {

                 final Date snapshotTaken = new Date(problems.get(0).created);

                 out.print("    <item>\n      <title>WebVM: Problems report for ");

                 out.print(snapshotTaken);

                 out.print("</title>\n      <link>");

                 out.print(link);

                 out.print("</link>\n      <description>Problems report:&lt;br/&gt;");

                 out.print(ProblemReport.escape(ProblemReport.toHtml(problems)));

                 out.print("</description>\n      <pubDate>");

                 out.print(snapshotTaken);

                 out.print("</pubDate>\n      <guid>");

                 out.print(snapshotTaken.getTime());

                 out.println("</guid>\n    </item>");

             }

             out.println("  </channel>\n</rss>\n");

         } finally {

             out.close();

         }

     }

     private static String getContextRoot(HttpServletRequest request) {

         final String requrl = request.getRequestURL().toString();

         final int contextRootEnd = requrl.indexOf("/rss.xml");

         if (contextRootEnd < 0) {

             return null;

         }

         return requrl.substring(0, contextRootEnd);

     }

     /** 

      * Handles the HTTP <code>GET</code> method.

      * @param request servlet request

      * @param response servlet response

      * @throws ServletException if a servlet-specific error occurs

      * @throws IOException if an I/O error occurs

      */

     @Override

     protected void doGet(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         processRequest(request, response);

     }

     /** 

      * Handles the HTTP <code>POST</code> method.

      * @param request servlet request

      * @param response servlet response

      * @throws ServletException if a servlet-specific error occurs

      * @throws IOException if an I/O error occurs

      */

     @Override

     protected void doPost(HttpServletRequest request, HttpServletResponse response)

             throws ServletException, IOException {

         processRequest(request, response);

     }

     /** 

      * Returns a short description of the servlet.

      * @return a String containing servlet description

      */

     @Override

     public String getServletInfo() {

         return "RSS Feed";

     }

 }