/* Copyright 2009-2012 Capgemini 
    * 
    * Licensed under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with the
    * License. You may obtain a copy of the License at
    * 
    * http://www.apache.org/licenses/LICENSE-2.0
    * 
    * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations under
   * the License.
   */
  package net.sourceforge.statelessfilter.backend.session;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.Map;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpSession;
  
  import net.sourceforge.statelessfilter.backend.ISessionBackend;
  import net.sourceforge.statelessfilter.backend.ISessionData;
  import net.sourceforge.statelessfilter.backend.support.CookieDataSupport;
  import net.sourceforge.statelessfilter.filter.Configuration;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Backend based on an unencrypted cookie. Can be used for non sensitive data.
   * Cookie can be compressed to save bandwidth.
   * 
   * <p>
   * Parameters :
   * </p>
   * <ul>
   * <li>cookiename : name of the cookie</li>
   * <li>compress : enable cookie compression (gzip) when value is "true"</li>
   * </ul>
   * 
   * @author Nicolas Richeton - Capgemini
   * 
   */
  public class SessionBackend implements ISessionBackend {
  	private static final String ID = "session"; //$NON-NLS-1$
  	private static final String SESSION_SESSION = "stateless.session";
  	Logger logger = LoggerFactory.getLogger(SessionBackend.class);
  
  	public SessionBackend() {
  		// empty constructor
  	}
  
  	/**
  	 * @see net.sourceforge.statelessfilter.backend.session.ISessionBackend#destroy()
  	 */
  
  	public void destroy() {
  		// Nothing to clean
  	}
  
  	/**
  	 * @see net.sourceforge.statelessfilter.backend.session.ISessionBackend#getId()
  	 */
  
  	public String getId() {
  		return ID;
  	}
  
  	/**
  	 * @see net.sourceforge.statelessfilter.backend.session.ISessionBackend#init(java.util.Map)
  	 */
  
  	public void init(Map<String, String> config) throws Exception {
  		// Nothing to init
  	}
  
  	public String isBufferingRequired() {
  		return Configuration.BUFFERING_HEADERS;
  	}
  
  	/**
  	 * @see net.sourceforge.statelessfilter.backend.session.ISessionBackend#restore(javax.servlet.http.HttpServletRequest)
  	 */
  
  	public ISessionData restore(HttpServletRequest request) {
  		HttpSession session = request.getSession(false);
  		if (session != null) {
  			CookieDataSupport s = (CookieDataSupport) session
  					.getAttribute(SESSION_SESSION);
  			if (s != null && s.isValid()) {
  				return s;
  			}
  		}
  
  		return null;
 	}
 
 	/**
 	 * @see net.sourceforge.statelessfilter.backend.ISessionBackend#save(net.sourceforge.statelessfilter.backend.ISessionData,
 	 *      java.util.List, javax.servlet.http.HttpServletRequest,
 	 *      javax.servlet.http.HttpServletResponse)
 	 */
 	public void save(ISessionData session, List<String> dirtyAttributes,
 			HttpServletRequest request, HttpServletResponse response)
 			throws IOException {
 		if (session != null) {
 			HttpSession httpSession = request.getSession(true);
 
 			if (!session.isValid()) {
 				httpSession.invalidate();
 			} else {
 				CookieDataSupport cookieData = new CookieDataSupport(session);
 				httpSession.setAttribute(SESSION_SESSION, cookieData);
 			}
 		} else {
 			// Session is null
 			HttpSession httpSession = request.getSession(false);
 			if (httpSession != null) {
 				httpSession.setAttribute(SESSION_SESSION, null);
 			}
 		}
 
 	}
 }