/**

  * Copyright 2005-2011 The Kuali Foundation

  *

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  *

  * 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 org.kuali.rice.kew.web;

 import java.io.IOException;

 import javax.servlet.Filter;

 import javax.servlet.FilterChain;

 import javax.servlet.FilterConfig;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 import org.kuali.rice.kew.api.KewApiServiceLocator;

 import org.kuali.rice.kew.api.preferences.Preferences;

 import org.kuali.rice.kew.api.preferences.PreferencesService;

 import org.kuali.rice.kew.service.KEWServiceLocator;

 import org.kuali.rice.kew.api.KewApiConstants;

 import org.kuali.rice.krad.UserSession;

 import org.kuali.rice.krad.util.KRADUtils;

 /**

  * This class establishes and initializes the KEW Preferences after a user logs in.

  * 

  * <p>

  * This filter assumes that a UserSession is already established.

  * </p>

  * 

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class UserPreferencesFilter implements Filter {

         private static final Log LOG = LogFactory.getLog(UserPreferencesFilter.class);

         private FilterConfig filterConfig;

         private PreferencesService preferencesService;

         @Override

         public void init(FilterConfig config) throws ServletException {

                 this.filterConfig = config;

         }

         @Override

         public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

                 this.doFilter((HttpServletRequest) request, (HttpServletResponse) response, chain);

         }

         private void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException {

                 final UserSession session = KRADUtils.getUserSessionFromRequest(request);

                 if (session == null) {

                         throw new IllegalStateException("A user session has not been established");

                 }

                 final String principalId = session.getPrincipalId();

                 if (session.retrieveObject(KewApiConstants.PREFERENCES) == null) {

                         final Preferences preferences = retrievePreferences(principalId);

                         session.addObject(KewApiConstants.PREFERENCES, preferences);

                 }

                 chain.doFilter(request, response);

         }

         @Override

         public void destroy() {

                 filterConfig = null;

         }

     private Preferences retrievePreferences(String principalId) {

             Preferences preferences = this.getPreferenceService().getPreferences(principalId);

         if (preferences.isRequiresSave()) {

             LOG.info("Detected that user preferences require saving.");

             this.getPreferenceService().savePreferences(principalId, preferences);

             preferences = this.getPreferenceService().getPreferences(principalId);

         }

         return preferences;

     }

     private PreferencesService getPreferenceService() {

             if (this.preferencesService == null) {

                     this.preferencesService = KewApiServiceLocator.getPreferencesService();

             }

             return this.preferencesService;

     }

 }