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

  * 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 org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import de.laures.cewolf.CewolfException;

 import de.laures.cewolf.ChartImage;

 import de.laures.cewolf.Storage;

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

 /**

  * @author glaures

  */

 public abstract class AbstractSessionStorage implements Storage

 {

   private static final Log log = LogFactory.getLog(AbstractSessionStorage.class);

   /**

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

    */

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

   {

     if ( contains(cid, pageContext) )

     {

       return getKey(cid);

     }

     log.debug("storing chart " + cid);

     final HttpSession session = pageContext.getSession();

     //String key = getKey(cid);

     return storeChartImage(cid, session);

   }

   /**

    * @see de.laures.cewolf.Storage#getChartImage(String)

    */

   public ChartImage getChartImage( String id, HttpServletRequest request )

   {

     HttpSession session = request.getSession();

     return (ChartImage) session.getAttribute(id);

   }

   public boolean contains( ChartImage cid, PageContext pageContext )

   {

     return pageContext.getSession().getAttribute(getKey(cid)) != null;

   }

   public final String getKey( ChartImage cid )

   {

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

   }

   protected String storeChartImage( ChartImage cid, HttpSession session ) throws CewolfException

   {

     final String sessionKey = getKey(cid);

     synchronized (session)

     {

       session.setAttribute(sessionKey, getCacheObject(cid));

     }

     return sessionKey;

   }

 	/**

 	 */

 	public String removeChartImage(String imgKey, HttpServletRequest request)

 			throws CewolfException {

 		final HttpSession session = request.getSession();

 		if (session == null)

 		{

 			return imgKey;

 		}

 		return removeChartImage(imgKey, session);		

 	}

 	/**

 	 * @param cid

 	 * @param session

 	 * @return

 	 * @throws CewolfException

 	 */

 	protected String removeChartImage(String cid, HttpSession session)

 			throws CewolfException {

 		synchronized (session) {

 			session.removeAttribute(cid);

 		}

 		return cid;

 	}

   protected abstract Object getCacheObject( ChartImage cid ) throws CewolfException;

   /**

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

    */

   public void init( ServletContext servletContext ) throws CewolfException

   {

   }

 }