/* ================================================================

  * Cewolf : Chart enabling Web Objects Framework

  * ================================================================

  *

  * Project Info:  http://cewolf.sourceforge.net

  * Project Lead:  Guido Laures (guido@laures.de);

  *

  * (C) Copyright 2002, by Guido Laures

  *

  * This library is free software; you can redistribute it and/or modify it under the terms

  * of the GNU Lesser General Public License as published by the Free Software Foundation;

  * either version 2.1 of the License, or (at your option) any later version.

  *

  * This library 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 Lesser General Public License for more details.

  *

  * You should have received a copy of the GNU Lesser General Public License along with this

  * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,

  * Boston, MA 02111-1307, USA.

  */

 package de.laures.cewolf;

 import java.io.IOException;

 import java.io.OutputStream;

 import java.io.Writer;

 import java.util.Enumeration;

 import javax.servlet.ServletConfig;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import de.laures.cewolf.util.RenderingHelper;

 /**

  * The rendering servlet of Cewolf. It is resposible for writing an entire chart

  * img into the response stream of the client. Everything needed for this is

  * prepared already by the ChartImgTag resp. LegendTag. The ID of a chart image

  * is passed to this servlet as a request parameter. After that the image object

  * is retrieved from the server side session based image cache. This servlet

  * must be configured in web.xml of the web application in order to use Cewolf

  * services. The servlet's URL relative to the web apps root is used as the

  * renderer attribute of the ChartImgTag resp. LegendTag in the JSP page.

  * 

  * @see de.laures.cewolf.taglib.tags.ChartImgTag

  * @see de.laures.cewolf.taglib.tags.LegendTag

  * @author Guido Laures

  * @since 0.1

  */

 public class CewolfRenderer extends HttpServlet implements WebConstants

 {

   public static final String  INIT_CONFIG  = "CewolfRenderer_Init_Config";

   private static final String STATE        = "state";

   private boolean             debugged     = false;

   private int                 requestCount = 0;

   private Byte 					lock = Byte.valueOf("0");

   private Configuration       config       = null;

   public void init( ServletConfig servletCfg ) throws ServletException

   {

     super.init(servletCfg);

     //Store init config params for processing by the Configuration

     servletCfg.getServletContext().setAttribute(INIT_CONFIG, servletCfg);

     config = Configuration.getInstance(servletCfg.getServletContext());

     if (config != null)

       this.debugged = config.isDebugged();

     else

       this.debugged = false;

   }

   /**

    * Processes HTTP <code>GET</code> request. Renders the chart or the lengend

    * into the client's response stream.

    * 

    * @param request

    *          servlet request

    * @param response

    *          servlet response

    * @throws ServletException

    *           when the production of data could not be handled by the

    *           configured DatasetProcuder

    */

   public void printParameters(HttpServletRequest request)

   {

     Enumeration enumeration = request.getParameterNames();

     while (enumeration.hasMoreElements())

     {

       String cur = (String)enumeration.nextElement();

       Object obj = request.getParameter(cur);

       log("Request Parameter -> " + cur + " Value -> " + obj.toString());

     }

   }

   protected void doGet( HttpServletRequest request, HttpServletResponse response ) throws ServletException, IOException

   {

     if ( debugged )

     {

       logRequest(request);

     }

     addHeaders(response);

     if ( request.getParameter(STATE) != null || !request.getParameterNames().hasMoreElements() )

     {

       requestState(response);

       return;

     }

     synchronized (lock) {

     	requestCount++;

 	}

     int width = 400;

     int height = 400;

     boolean removeAfterRendering = false;

     if ( request.getParameter(REMOVE_AFTER_RENDERING) != null )

     {

     	removeAfterRendering = true;

     }

     if ( request.getParameter(WIDTH_PARAM) != null )

     {

       width = Integer.parseInt(request.getParameter(WIDTH_PARAM));

     }

     if ( request.getParameter(HEIGHT_PARAM) != null )

     {

       height = Integer.parseInt(request.getParameter(HEIGHT_PARAM));

     }

     // determine the cache key

     String imgKey = request.getParameter(IMG_PARAM);

     if ( imgKey == null )

     {

       logAndRenderException(new ServletException("no '" + IMG_PARAM + "' parameter provided for Cewolf servlet."), response, width, height);

       return;

     }

     Storage storage = config.getStorage();

     ChartImage chartImage = storage.getChartImage(imgKey, request);

     if ( chartImage == null )

     {

       renderImageExpiry(response, width, height);

       return;

     }

     // send the img

     try

     {

       long start = System.currentTimeMillis();

       // response.setContentType(cid.getMimeType());

       final int size = chartImage.getSize();

       response.setContentType(chartImage.getMimeType());

       response.setContentLength(size);

       response.setBufferSize(size);

       response.setStatus(HttpServletResponse.SC_OK);

       response.getOutputStream().write(chartImage.getBytes());

       long last = System.currentTimeMillis() - start;

       if ( debugged )

       {

         log("creation time for chart " + imgKey + ": " + last + "ms.");

       }

     }

     catch (Throwable t)

     {

       logAndRenderException(t, response, width, height);

     }

     finally

     {

     	if (removeAfterRendering)

     	{

     		try {

 				storage.removeChartImage(imgKey , request);

 			} catch (CewolfException e) {

 				log("Removal of image failed", e);

 			}

     	}

     }

   }

   /**

    * Method addHeaders.

    * 

    * @param response

    */

   private void addHeaders( HttpServletResponse response )

   {

     response.setDateHeader("Expires", System.currentTimeMillis());

   }

   /**

    * Method requestState.

    * 

    * @param request

    * @param response

    */

   private void requestState( HttpServletResponse response ) throws IOException

   {

     Writer writer = response.getWriter();

     writer.write("<HTML><BODY>");

     /*

      * StateDescriptor sd = (StateDescriptor)

      * ChartImageCacheFactory.getChartImageBase( getServletContext());

      * writer.write(HTMLStateTable.getStateTable(sd));

      */

     writer.write("<b>Cewolf servlet up and running.</b><br>");

     writer.write("Requests served so far: " + requestCount);

     writer.write("</HTML></BODY>");

     writer.close();

   }

   private void logAndRenderException( Throwable ex, HttpServletResponse response, int width, int height ) throws IOException

   {

     log(ex.getMessage(), ex);

     response.setContentType("image/jpg");

     OutputStream out = response.getOutputStream();

     RenderingHelper.renderException(ex, width, height, out);

     out.close();

   }

   /**

    * Method renderImageExpiry.

    * 

    * @param response

    * @param width

    * @param height

    */

   private void renderImageExpiry( HttpServletResponse response, int width, int height ) throws IOException

   {

     response.setContentType("image/jpg");

     OutputStream out = response.getOutputStream();

     RenderingHelper.renderMessage("This chart has expired. Please reload.", width, height, out);

     out.close();

   }

   private void logRequest( HttpServletRequest request ) throws IOException

   {

     log("Cewolf request:");

     log("Actual Request values:");

     printParameters(request);

     Enumeration headerNames = request.getHeaderNames();

     while ( headerNames.hasMoreElements() )

     {

       String name = (String) headerNames.nextElement();

       Enumeration values = request.getHeaders(name);

       StringBuffer value = new StringBuffer();

       while ( values.hasMoreElements() )

       {

         value.append((String) values.nextElement() + ",");

       }

       // cut last comma

       if ( value.length() > 0 )

         value.setLength(value.length() - 1);

       log(name + ": " + value);

     }

   //  InputStream body = request.getInputStream();

  //   byte[] bodyData = new byte[body.available()];

  //   body.read(bodyData);

  //   body.close();

  //   log(new String(bodyData));

   }

 }