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

 * 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));

  }

}