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

 * 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.storage;

import java.io.Serializable;

import javax.servlet.ServletContext;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpSession;

import javax.servlet.jsp.PageContext;

import de.laures.cewolf.CewolfException;

import de.laures.cewolf.ChartImage;

import de.laures.cewolf.Storage;

import de.laures.cewolf.taglib.util.KeyGenerator;

/**

 * Storage stores images in session, but expires them after a certain time. 

 * This expiration time defaults to 300 seconds, and can be changed by adding 

 * the timeout="xxx" parameter to <cewolf:img> and <cewolf:legend> tags.

 * 

 * @author brianf

 */

public class LongTermSessionStorage implements Storage

{

  public final String getKey( ChartImage cid )

  {

    return String.valueOf(KeyGenerator.generateKey((Serializable) cid));

  }

  /*

   * (non-Javadoc)

   * 

   * @see de.laures.cewolf.Storage#storeChartImage(de.laures.cewolf.ChartImage,

   *      javax.servlet.jsp.PageContext)

   */

  public String storeChartImage( ChartImage chartImage, PageContext pageContext ) throws CewolfException

  {

    HttpSession session = pageContext.getSession();

    SessionStorageGroup ssg = (SessionStorageGroup) session.getAttribute("CewolfCharts");

    if ( ssg == null )

    {

      ssg = new SessionStorageGroup();

      session.setAttribute("CewolfCharts", ssg);

    }

    String cid = getKey(chartImage);

    SessionStorageItem ssi = new SessionStorageItem(chartImage, cid, chartImage.getTimeoutTime());

    ssg.put(cid, ssi);

    return cid;

  }

  /*

   * (non-Javadoc)

   * 

   * @see de.laures.cewolf.Storage#getChartImage(java.lang.String,

   *      javax.servlet.http.HttpServletRequest)

   */

  public ChartImage getChartImage( String id, HttpServletRequest request )

  {

    HttpSession session = request.getSession();

    ChartImage chart = null;

    SessionStorageGroup ssg = (SessionStorageGroup) session.getAttribute("CewolfCharts");

    if ( ssg != null )

    {

      SessionStorageItem ssi = (SessionStorageItem) ssg.get(id);

      if ( ssi != null )

      {

        chart = ssi.getChart();

      }

    }

    return chart;

  }

  /*

   * (non-Javadoc)

   * 

   * @see de.laures.cewolf.Storage#init(javax.servlet.ServletContext)

   */

  public void init( ServletContext servletContext ) throws CewolfException {

  }

  /**

   * @see de.laures.cewolf.Storage#removeChartImage(java.lang.String, javax.servlet.jsp.PageContext)

   */

  public String removeChartImage(String cid, HttpServletRequest request) throws CewolfException {

	  HttpSession session = request.getSession();

	  // No session exit

	  if (session == null)

	  {

		  return cid;

	  }

	  SessionStorageGroup ssg = (SessionStorageGroup) session.getAttribute("CewolfCharts");

	  if ( ssg == null )

	  {

		  // No group exit

		  return cid;

	  }

	  ssg.remove(cid);

	  return cid;  

  }

}