// ========================================================================
   // Copyright (c) 1999-2009 Mort Bay Consulting Pty. Ltd.
   // ------------------------------------------------------------------------
   // All rights reserved. This program and the accompanying materials
   // are made available under the terms of the Eclipse Public License v1.0
   // and Apache License v2.0 which accompanies this distribution.
   // The Eclipse Public License is available at 
   // http://www.eclipse.org/legal/epl-v10.html
   // The Apache License v2.0 is available at
  // http://www.opensource.org/licenses/apache2.0.php
  // You may elect to redistribute this code under either of these licenses. 
  // ========================================================================
  package org.eclipse.jetty.server.handler;
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.StringWriter;
  import java.io.Writer;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.http.HttpHeaders;
  import org.eclipse.jetty.http.HttpMethods;
  import org.eclipse.jetty.http.HttpStatus;
  import org.eclipse.jetty.http.MimeTypes;
  import org.eclipse.jetty.server.HttpConnection;
  import org.eclipse.jetty.util.ByteArrayISO8859Writer;
  import org.eclipse.jetty.util.StringUtil;
  
  
  /* ------------------------------------------------------------ */
  /** Handler for Error pages
   * A handler that is registered at the org.eclipse.http.ErrorHandler
   * context attributed and called by the HttpResponse.sendError method to write a
   * error page.
   * 
   * 
   */
  public class ErrorHandler extends AbstractHandler
  {
      boolean _showStacks=true;
      
      /* ------------------------------------------------------------ */
      /* 
       * @see org.eclipse.jetty.server.server.Handler#handle(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, int)
       */
      public void handle(String target, HttpServletRequest request, HttpServletResponse response) throws IOException
      {
          HttpConnection connection = HttpConnection.getCurrentConnection();
          connection.getRequest().setHandled(true);
          String method = request.getMethod();
          if(!method.equals(HttpMethods.GET) && !method.equals(HttpMethods.POST))
              return;
          response.setContentType(MimeTypes.TEXT_HTML_8859_1);        
          response.setHeader(HttpHeaders.CACHE_CONTROL, "must-revalidate,no-cache,no-store");
          ByteArrayISO8859Writer writer= new ByteArrayISO8859Writer(4096);
          handleErrorPage(request, writer, connection.getResponse().getStatus(), connection.getResponse().getReason());
          writer.flush();
          response.setContentLength(writer.size());
          writer.writeTo(response.getOutputStream());
          writer.destroy();
      }
  
      /* ------------------------------------------------------------ */
      protected void handleErrorPage(HttpServletRequest request, Writer writer, int code, String message)
          throws IOException
      {
          writeErrorPage(request, writer, code, message, _showStacks);
      }
      
      /* ------------------------------------------------------------ */
      protected void writeErrorPage(HttpServletRequest request, Writer writer, int code, String message, boolean showStacks)
          throws IOException
      {
          if (message == null)
              message=HttpStatus.getCode(code).getMessage();
          else
          {
              message= StringUtil.replace(message, "&", "&");
              message= StringUtil.replace(message, "<", "&lt;");
              message= StringUtil.replace(message, ">", "&gt;");
          }
  
          writer.write("<html>\n<head>\n");
          writeErrorPageHead(request,writer,code,message);
          writer.write("</head>\n<body>");
          writeErrorPageBody(request,writer,code,message,showStacks);
          writer.write("\n</body>\n</html>\n");
      }
  
      /* ------------------------------------------------------------ */
      protected void writeErrorPageHead(HttpServletRequest request, Writer writer, int code, String message)
          throws IOException
      {
          writer.write("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=ISO-8859-1\"/>\n");
          writer.write("<title>Error ");
          writer.write(Integer.toString(code));
          writer.write(' ');
          if (message!=null)
             writer.write(message);
         writer.write("</title>\n");    
     }
 
     /* ------------------------------------------------------------ */
     protected void writeErrorPageBody(HttpServletRequest request, Writer writer, int code, String message, boolean showStacks)
         throws IOException
     {
         String uri= request.getRequestURI();
         if (uri!=null)
         {
             uri= StringUtil.replace(uri, "&", "&amp;");
             uri= StringUtil.replace(uri, "<", "&lt;");
             uri= StringUtil.replace(uri, ">", "&gt;");
         }
         
         writeErrorPageMessage(request,writer,code,message,uri);
         if (showStacks)
             writeErrorPageStacks(request,writer);
         writer.write("<hr /><i><small>Powered by Jetty://</small></i>");
         for (int i= 0; i < 20; i++)
             writer.write("<br/>                                                \n");
     }
 
     /* ------------------------------------------------------------ */
     protected void writeErrorPageMessage(HttpServletRequest request, Writer writer, int code, String message,String uri)
     throws IOException
     {
         writer.write("<h2>HTTP ERROR ");
         writer.write(Integer.toString(code));
         writer.write("</h2>\n<p>Problem accessing ");
         writer.write(uri);
         writer.write(". Reason:\n<pre>    ");
         writer.write(message);
         writer.write("</pre></p>");
     }
 
     /* ------------------------------------------------------------ */
     protected void writeErrorPageStacks(HttpServletRequest request, Writer writer)
         throws IOException
     {
         Throwable th = (Throwable)request.getAttribute("javax.servlet.error.exception");
         while(th!=null)
         {
             writer.write("<h3>Caused by:</h3><pre>");
             StringWriter sw = new StringWriter();
             PrintWriter pw = new PrintWriter(sw);
             th.printStackTrace(pw);
             pw.flush();
             writer.write(sw.getBuffer().toString());
             writer.write("</pre>\n");
 
             th =th.getCause();
         }
     }
         
 
     /* ------------------------------------------------------------ */
     /**
      * @return True if stack traces are shown in the error pages
      */
     public boolean isShowStacks()
     {
         return _showStacks;
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @param showStacks True if stack traces are shown in the error pages
      */
     public void setShowStacks(boolean showStacks)
     {
         _showStacks = showStacks;
     }
 
 }