package org.apache.turbine.services.session;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   */
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Hashtable;
  import java.util.Iterator;
  import java.util.Map;
  import javax.servlet.http.HttpSession;
  
  import org.apache.turbine.om.security.User;
  import org.apache.turbine.services.TurbineBaseService;
  
  /***
   * The SessionService allows thread-safe access to the current
   * sessions of the current context.  The session objects that are
   * cached by this service are obtained through a listener, which must
   * be configured via your web application's <code>web.xml</code>
   * deployement descriptor as follows:
   *
   * <blockquote><code><pre>
   * &lt;listener&gt;
   *   &lt;listener-class&gt;
   *     org.apache.turbine.session.SessionListener
   *   &lt;/listener-class&gt;
   * &lt;/listener&gt;
   * </pre></code></blockquote>
   *
   * @author <a href="mailto:quintonm@bellsouth.net">Quinton McCombs</a>
   * @author <a href="mailto:dlr@collab.net">Daniel Rall</a>
   * @since 2.3
   * @version $Id: TurbineSessionService.java 534527 2007-05-02 16:10:59Z tv $
   * @see org.apache.turbine.services.session.TurbineSession
   * @see org.apache.turbine.services.session.SessionListener
   */
  public class TurbineSessionService
          extends TurbineBaseService
          implements SessionService
  {
      /*** Map of active sessions */
      private Map activeSessions;
  
      /***
       * Gets a list of the active sessions.
       *
       * @return A copy of the list of <code>HttpSession</code> objects.
       */
      public Collection getActiveSessions()
      {
          // Sync externally to allow ArrayList's ctor to iterate
          // activeSessions' values in a thread-safe fashion.
          synchronized (activeSessions)
          {
              return new ArrayList(activeSessions.values());
          }
      }
  
      /***
       * Adds a session to the current list.  This method should only be
       * called by the listener.
       *
       * @param session Session to add
       */
      public void addSession(HttpSession session)
      {
          activeSessions.put(session.getId(), session);
      }
  
      /***
       * Removes a session from the current list.  This method should only be
       * called by the listener.
       *
       * @param session Session to remove
       */
      public void removeSession(HttpSession session)
      {
          activeSessions.remove(session.getId());
      }
  
      /***
       * Determines if a given user is currently logged in.  The actual
      * implementation of the User object must implement the equals()
      * method.  By default, Torque based objects (liek TurbineUser)
      * have an implementation of equals() that will compare the
      * result of getPrimaryKey().
      *
      * @param user User to check for
      * @return true if the user is logged in on one of the
      * active sessions.
      */
     public boolean isUserLoggedIn(User user)
     {
         return getActiveUsers().contains(user);
     }
 
     /***
      * Gets a collection of all user objects representing the users currently
      * logged in.  This will exclude any instances of anonymous user that
      * Turbine will use before the user actually logs on.
      *
      * @return A set of {@link org.apache.turbine.om.security.User} objects.
      */
     public Collection getActiveUsers()
     {
         Collection users;
         synchronized (activeSessions)
         {
             // Pre-allocate a list which won't need expansion more
             // than once.
             users = new ArrayList((int) (activeSessions.size() * 0.7));
             for (Iterator i = activeSessions.values().iterator(); i.hasNext();)
             {
                 User u = getUserFromSession((HttpSession) i.next());
                 if (u != null && u.hasLoggedIn())
                 {
                     users.add(u);
                 }
             }
         }
 
         return users;
     }
 
     /***
      * Gets the User object of the the specified HttpSession.
      *
      * @param session The session from which to extract a user.
      * @return The Turbine User object.
      */
     public User getUserFromSession(HttpSession session)
     {
         // Not sure of other containers, but Tomcat 5.0.28 sometimes returns
         // invalid sessions which will result in IllegalStateException when
         // session.getAttribute() is invoked below.
         try
         {
             return (User) session.getAttribute(User.SESSION_KEY);
         }
         catch (IllegalStateException e)
         {
             return null;
         }
     }
 
     /***
      * Gets the HttpSession by the session identifier
      *
      * @param sessionId The unique session identifier.
      * @return The session keyed by the specified identifier.
      */
     public HttpSession getSession(String sessionId)
     {
         return (HttpSession) this.activeSessions.get(sessionId);
     }
 
     /***
      * Get a collection of all session on which the given user
      * is logged in.
      *
      * @param user the user
      * @return Collection of HtttSession objects
      */
     public Collection getSessionsForUser(User user)
     {
         Collection sessions = new ArrayList();
         synchronized (activeSessions)
         {
             for (Iterator i = activeSessions.values().iterator(); i.hasNext();)
             {
                 HttpSession session = (HttpSession) i.next();
                 User u = this.getUserFromSession(session);
                 if (user.equals(u))
                 {
                     sessions.add(session);
                 }
             }
         }
 
         return sessions;
     }
 
 
     // ---- Service initilization ------------------------------------------
 
     /***
      * Initializes the service
      */
     public void init()
     {
         this.activeSessions = new Hashtable();
 
         setInit(true);
     }
 
     /***
      * Returns to uninitialized state.
      */
     public void shutdown()
     {
         this.activeSessions = null;
 
         setInit(false);
     }
 
 }