/**
    * This file Copyright (c) 2003-2010 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 info.magnolia.cms.core.HierarchyManager;
  import info.magnolia.cms.security.AccessManager;
  import info.magnolia.cms.security.Permission;
  import info.magnolia.cms.security.PermissionImpl;
  import info.magnolia.cms.security.SystemUserManager;
  import info.magnolia.cms.util.UrlPattern;
  import info.magnolia.cms.util.WorkspaceAccessUtil;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import javax.jcr.RepositoryException;
  import javax.jcr.UnsupportedRepositoryOperationException;
  import javax.jcr.observation.Event;
  import javax.jcr.observation.EventIterator;
  import javax.jcr.observation.EventListener;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Uses a single full access AccessManager. JCR sessions are only released if no event listener were registered.
   */
  public class SystemRepositoryStrategy extends AbstractRepositoryStrategy {
  
      private static final Logger log = LoggerFactory.getLogger(SystemRepositoryStrategy.class);
  
      private AccessManager accessManager;
    
      private Map<String, EventListener> observedHMs = new HashMap<String, EventListener>();
   
  
      public SystemRepositoryStrategy(SystemContext context) {
      }
  
      public AccessManager getAccessManager(String repositoryId, String workspaceId) {
          if (accessManager == null) {
              accessManager = WorkspaceAccessUtil.getInstance().createAccessManager(getSystemPermissions(), repositoryId, workspaceId);
          }
  
          return accessManager;
      }
  
      protected List<Permission> getSystemPermissions() {
          List<Permission> acl = new ArrayList<Permission>();
          UrlPattern p = UrlPattern.MATCH_ALL;
          Permission permission = new PermissionImpl();
          permission.setPattern(p);
          permission.setPermissions(Permission.ALL);
          acl.add(permission);
          return acl;
      }
  
      protected String getUserId() {
          return SystemUserManager.SYSTEM_USER;
      }
  
      public void release() {
          if (!observedHMs.isEmpty()) {
              for (Map.Entry<String, EventListener> entry : observedHMs.entrySet()) {
                  final String[] key = entry.getKey().split("_");
                  final HierarchyManager hm = super.getHierarchyManager(key[0], key[1]);
                 try {
                     hm.getWorkspace().getObservationManager().removeEventListener(entry.getValue());
                 } catch (UnsupportedRepositoryOperationException e) {
                     log.error("Failed to remove listener from short living session. Session doesn't support listener removal.");
                 } catch (RepositoryException e) {
                     log.error("Failed to remove listener from short living session. Will not be able to release this session.");
                 }
             }
             // release reference to listener so it can be GCed
             observedHMs.clear();
         }
         super.release(true);
     }
 
     @Override
     public HierarchyManager getHierarchyManager(String repositoryId, String workspaceId) {
         final HierarchyManager hm = super.getHierarchyManager(repositoryId, workspaceId);
         final String key = repositoryId + "_" + workspaceId;
         if (!observedHMs.keySet().contains(key)) {
             final EventListener listener = new EventListener() {
 
                 public void onEvent(EventIterator iterator) {
                     // reload everything
                     try {
                         hm.refresh(true);
                     } catch (RepositoryException e) {
                         log.error("Failed to refresh short living session after update. Session will not be able to see content changes if repository uses update-on-read strategy.");
                     }
                 }
             };
             try {
                 hm.getWorkspace().getObservationManager().addEventListener(listener, Event.NODE_ADDED | Event.NODE_REMOVED | Event.PROPERTY_ADDED | Event.PROPERTY_CHANGED | Event.PROPERTY_REMOVED, "/", true, null, null, false);
                 observedHMs.put(key, listener);
             } catch (UnsupportedRepositoryOperationException e) {
                 log.warn("Repository doesn't support observation. Observers will not be notified of changes in repository.");
             } catch (RepositoryException e) {
                 log.error("Failed to register observer for repository updates.");
             }
             //ObservationUtil.registerChangeListener(hm.getName(), "/", listener );
         }
         return hm;
     }
 }