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

 * 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

  {

  }

}