/**
    * This file Copyright (c) 2003-2011 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.context;
  
  import java.util.HashMap;
  import java.util.Map;
  import javax.inject.Inject;
  import javax.jcr.LoginException;
  import javax.jcr.RepositoryException;
  import javax.jcr.Session;
  import javax.jcr.observation.EventListener;
  import javax.jcr.observation.EventListenerIterator;
  import javax.jcr.observation.ObservationManager;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import info.magnolia.repository.RepositoryManager;
  
  
  /**
   * Basic implementation of the <code>RepositoryAcquiringStrategy</code> providing storage of JCR sessions and hierarchy manager instances to extending classes.
   *
   * @version $Id$
   */
  public abstract class AbstractRepositoryStrategy implements JCRSessionStrategy {
      private static final Logger log = LoggerFactory.getLogger(AbstractRepositoryStrategy.class);
  
      private final Map<String, Session> jcrSessions = new HashMap<String, Session>();
  
      protected final RepositoryManager repositoryManager;
  
      @Inject
      protected AbstractRepositoryStrategy(RepositoryManager repositoryManager) {
          this.repositoryManager = repositoryManager;
      }
  
      @Override
      public Session getSession(String workspaceName) throws LoginException, RepositoryException {
          Session jcrSession = jcrSessions.get(workspaceName);
  
          if (jcrSession == null) {
              log.debug("creating jcr session {} by thread {}", workspaceName, Thread.currentThread().getName());
  
              jcrSession = internalGetSession(workspaceName);
              jcrSessions.put(workspaceName, jcrSession);
          }
  
          return jcrSession;
      }
  
      protected abstract Session internalGetSession(String workspaceName) throws RepositoryException;
  
      protected void release(boolean checkObservation) {
          log.debug("releasing jcr sessions");
          for (Session session : jcrSessions.values()) {
              releaseSession(session, checkObservation);
          }
          jcrSessions.clear();
      }
  
      protected void releaseSession(final Session session, boolean checkObservation) {
          final String workspaceName = session.getWorkspace().getName();
          if (session.isLive()) {
              try {
                  final ObservationManager observationManager = session.getWorkspace().getObservationManager();
                  final EventListenerIterator listeners = observationManager.getRegisteredEventListeners();
                  if (!checkObservation || !listeners.hasNext()) {
                     session.logout();
                     log.debug("logged out jcr session: {} by thread {}", session, Thread.currentThread().getName());
 
                 } else {
                     log.warn("won't close session because of registered observation listener {}", workspaceName);
                     if (log.isDebugEnabled()) {
                         while (listeners.hasNext()) {
                             EventListener listener = listeners.nextEventListener();
                             log.debug("registered listener {}", listener);
                         }
                     }
                 }
             }
             catch (RepositoryException e) {
                 log.error("can't check if event listeners are registered", e);
             }
         } else {
             log.warn("session has been already closed {}", workspaceName);
         }
     }
 
     /**
      * Returns the number of sessions managed by this strategy.
      */
     protected int getLocalSessionCount() {
         return jcrSessions.size();
     }
 }