//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.server.session;
  
  import java.lang.ref.WeakReference;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Random;
  import java.util.Set;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpSession;
  
  import org.eclipse.jetty.server.SessionIdManager;
  
  /* ------------------------------------------------------------ */
  /**
   * HashSessionIdManager. An in-memory implementation of the session ID manager.
   */
  public class HashSessionIdManager extends AbstractSessionIdManager
  {
      private final Map<String, Set<WeakReference<HttpSession>>> _sessions = new HashMap<String, Set<WeakReference<HttpSession>>>();
  
      /* ------------------------------------------------------------ */
      public HashSessionIdManager()
      {
      }
  
      /* ------------------------------------------------------------ */
      public HashSessionIdManager(Random random)
      {
          super(random);
      }
  
      /* ------------------------------------------------------------ */
      /**
       * @return Collection of String session IDs
       */
      public Collection<String> getSessions()
      {
          return Collections.unmodifiableCollection(_sessions.keySet());
      }
  
      /* ------------------------------------------------------------ */
      /**
       * @param id the id of the session
       * @return Collection of Sessions for the passed session ID
       */
      public Collection<HttpSession> getSession(String id)
      {
          ArrayList<HttpSession> sessions = new ArrayList<HttpSession>();
          Set<WeakReference<HttpSession>> refs =_sessions.get(id);
          if (refs!=null)
          {
              for (WeakReference<HttpSession> ref: refs)
              {
                  HttpSession session = ref.get();
                  if (session!=null)
                      sessions.add(session);
              }
          }
          return sessions;
      }
      
      /* ------------------------------------------------------------ */
      @Override
      protected void doStart() throws Exception
      {
          super.doStart();
      }
  
      /* ------------------------------------------------------------ */
      @Override
      protected void doStop() throws Exception
      {
          _sessions.clear();
          super.doStop();
      }
 
     /* ------------------------------------------------------------ */
     /**
      * @see SessionIdManager#idInUse(String)
      */
     @Override
     public boolean idInUse(String id)
     {
         synchronized (this)
         {
             return _sessions.containsKey(id);
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see SessionIdManager#addSession(HttpSession)
      */
     @Override
     public void addSession(HttpSession session)
     {
         String id = getClusterId(session.getId());
         WeakReference<HttpSession> ref = new WeakReference<HttpSession>(session);
 
         synchronized (this)
         {
             Set<WeakReference<HttpSession>> sessions = _sessions.get(id);
             if (sessions==null)
             {
                 sessions=new HashSet<WeakReference<HttpSession>>();
                 _sessions.put(id,sessions);
             }
             sessions.add(ref);
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see SessionIdManager#removeSession(HttpSession)
      */
     @Override
     public void removeSession(HttpSession session)
     {
         String id = getClusterId(session.getId());
 
         synchronized (this)
         {
             Collection<WeakReference<HttpSession>> sessions = _sessions.get(id);
             if (sessions!=null)
             {
                 for (Iterator<WeakReference<HttpSession>> iter = sessions.iterator(); iter.hasNext();)
                 {
                     WeakReference<HttpSession> ref = iter.next();
                     HttpSession s=ref.get();
                     if (s==null)
                     {
                         iter.remove();
                         continue;
                     }
                     if (s==session)
                     {
                         iter.remove();
                         break;
                     }
                 }
                 if (sessions.isEmpty())
                     _sessions.remove(id);
             }
         }
     }
 
     /* ------------------------------------------------------------ */
     /**
      * @see SessionIdManager#invalidateAll(String)
      */
     @Override
     public void invalidateAll(String id)
     {
         Collection<WeakReference<HttpSession>> sessions;
         synchronized (this)
         {
             sessions = _sessions.remove(id);
         }
 
         if (sessions!=null)
         {
             for (WeakReference<HttpSession> ref: sessions)
             {
                 AbstractSession session=(AbstractSession)ref.get();
                 if (session!=null && session.isValid())
                     session.invalidate();
             }
             sessions.clear();
         }
     }
     
     
     /* ------------------------------------------------------------ */
     @Override
     public void renewSessionId (String oldClusterId, String oldNodeId, HttpServletRequest request)
     {
         //generate a new id
         String newClusterId = newSessionId(request.hashCode());
 
 
         synchronized (this)
         {
             Set<WeakReference<HttpSession>> sessions = _sessions.remove(oldClusterId); //get the list of sessions with same id from other contexts
             if (sessions!=null)
             {
                 for (Iterator<WeakReference<HttpSession>> iter = sessions.iterator(); iter.hasNext();)
                 {
                     WeakReference<HttpSession> ref = iter.next();
                     HttpSession s = ref.get();
                     if (s == null)
                     {
                         continue;
                     }
                     else
                     {
                         if (s instanceof AbstractSession)
                         {
                             AbstractSession abstractSession = (AbstractSession)s;
                             abstractSession.getSessionManager().renewSessionId(oldClusterId, oldNodeId, newClusterId, getNodeId(newClusterId, request));
                         }
                     }
                 }
                 _sessions.put(newClusterId, sessions);
             }
         }
     }
 
 }