//
   //  ========================================================================
   //  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.gcloud.session;
  
  import java.util.Random;
  
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpSession;
  
  import org.eclipse.jetty.server.Handler;
  import org.eclipse.jetty.server.Server;
  import org.eclipse.jetty.server.SessionManager;
  import org.eclipse.jetty.server.handler.ContextHandler;
  import org.eclipse.jetty.server.session.AbstractSession;
  import org.eclipse.jetty.server.session.AbstractSessionIdManager;
  import org.eclipse.jetty.server.session.SessionHandler;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  
  import com.google.gcloud.datastore.Datastore;
  import com.google.gcloud.datastore.DatastoreFactory;
  import com.google.gcloud.datastore.Entity;
  import com.google.gcloud.datastore.Key;
  import com.google.gcloud.datastore.KeyFactory;
  
  
  
  /**
   * GCloudSessionIdManager
   *
   * 
   * 
   */
  public class GCloudSessionIdManager extends AbstractSessionIdManager
  {
      private  final static Logger LOG = Log.getLogger("org.eclipse.jetty.server.session");
      public static final int DEFAULT_IDLE_EXPIRY_MULTIPLE = 2;
      public static final String KIND = "GCloudSessionId";
      private Server _server;
      private Datastore _datastore;
      private KeyFactory _keyFactory;
      private GCloudConfiguration _config;
      
      
      
   
      /**
       * @param server
       */
      public GCloudSessionIdManager(Server server)
      {
          super();
          _server = server;
      }
  
      /**
       * @param server
       * @param random
       */
      public GCloudSessionIdManager(Server server, Random random)
      {
         super(random);
         _server = server;
      }
  
  
  
      /** 
       * Start the id manager.
       * @see org.eclipse.jetty.server.session.AbstractSessionIdManager#doStart()
       */
      @Override
      protected void doStart() throws Exception
      {
          if (_config == null)
              throw new IllegalStateException("No gcloud configuration specified");       
          
  
          _datastore = DatastoreFactory.instance().get(_config.getDatastoreOptions());
          _keyFactory = _datastore.newKeyFactory().kind(KIND);
    
          super.doStart();
      }
 
 
     
     /** 
      * Stop the id manager
      * @see org.eclipse.jetty.server.session.AbstractSessionIdManager#doStop()
      */
     @Override
     protected void doStop() throws Exception
     {
         super.doStop();
     }
 
     
    
 
     
     /** 
      * Check to see if the given session id is being
      * used by a session in any context.
      * 
      * This method will consult the cluster.
      * 
      * @see org.eclipse.jetty.server.SessionIdManager#idInUse(java.lang.String)
      */
     @Override
     public boolean idInUse(String id)
     {
         if (id == null)
             return false;
         
         String clusterId = getClusterId(id);
         
         //ask the cluster - this should also tickle the idle expiration timer on the sessionid entry
         //keeping it valid
         try
         {
             return exists(clusterId);
         }
         catch (Exception e)
         {
             LOG.warn("Problem checking inUse for id="+clusterId, e);
             return false;
         }
         
     }
 
     /** 
      * Remember a new in-use session id.
      * 
      * This will save the in-use session id to the cluster.
      * 
      * @see org.eclipse.jetty.server.SessionIdManager#addSession(javax.servlet.http.HttpSession)
      */
     @Override
     public void addSession(HttpSession session)
     {
         if (session == null)
             return;
 
         //insert into the store
         insert (((AbstractSession)session).getClusterId());
     }
 
   
 
     
     public GCloudConfiguration getConfig()
     {
         return _config;
     }
 
     public void setConfig(GCloudConfiguration config)
     {
         _config = config;
     }
 
     
     
     /** 
      * Remove a session id from the list of in-use ids.
      * 
      * This will remvove the corresponding session id from the cluster.
      * 
      * @see org.eclipse.jetty.server.SessionIdManager#removeSession(javax.servlet.http.HttpSession)
      */
     @Override
     public void removeSession(HttpSession session)
     {
         if (session == null)
             return;
 
         //delete from the cache
         delete (((AbstractSession)session).getClusterId());
     }
 
     /** 
      * Remove a session id. This compels all other contexts who have a session
      * with the same id to also remove it.
      * 
      * @see org.eclipse.jetty.server.SessionIdManager#invalidateAll(java.lang.String)
      */
     @Override
     public void invalidateAll(String id)
     {
         //delete the session id from list of in-use sessions
         delete (id);
 
 
         //tell all contexts that may have a session object with this id to
         //get rid of them
         Handler[] contexts = _server.getChildHandlersByClass(ContextHandler.class);
         for (int i=0; contexts!=null && i<contexts.length; i++)
         {
             SessionHandler sessionHandler = ((ContextHandler)contexts[i]).getChildHandlerByClass(SessionHandler.class);
             if (sessionHandler != null)
             {
                 SessionManager manager = sessionHandler.getSessionManager();
 
                 if (manager != null && manager instanceof GCloudSessionManager)
                 {
                     ((GCloudSessionManager)manager).invalidateSession(id);
                 }
             }
         }
 
     }
 
     /** 
      * Change a session id. 
      * 
      * Typically this occurs when a previously existing session has passed through authentication.
      * 
      * @see org.eclipse.jetty.server.session.AbstractSessionIdManager#renewSessionId(java.lang.String, java.lang.String, javax.servlet.http.HttpServletRequest)
      */
     @Override
     public void renewSessionId(String oldClusterId, String oldNodeId, HttpServletRequest request)
     {
         //generate a new id
         String newClusterId = newSessionId(request.hashCode());
 
         delete(oldClusterId);
         insert(newClusterId);
 
 
         //tell all contexts to update the id 
         Handler[] contexts = _server.getChildHandlersByClass(ContextHandler.class);
         for (int i=0; contexts!=null && i<contexts.length; i++)
         {
             SessionHandler sessionHandler = ((ContextHandler)contexts[i]).getChildHandlerByClass(SessionHandler.class);
             if (sessionHandler != null) 
             {
                 SessionManager manager = sessionHandler.getSessionManager();
 
                 if (manager != null && manager instanceof GCloudSessionManager)
                 {
                     ((GCloudSessionManager)manager).renewSessionId(oldClusterId, oldNodeId, newClusterId, getNodeId(newClusterId, request));
                 }
             }
         }
 
     }
 
     
     
     /**
      * Ask the datastore if a particular id exists.
      * 
      * @param id
      * @return
      */
     protected boolean exists (String id)
     {
         if (_datastore == null)
             throw new IllegalStateException ("No DataStore");
         Key key = _keyFactory.newKey(id);
         return _datastore.get(key) != null;
     }
     
 
     /**
      * Put a session id into the cluster.
      * 
      * @param id
      */
     protected void insert (String id)
     {        
         if (_datastore == null)
             throw new IllegalStateException ("No DataStore");
 
         Entity entity = Entity.builder(makeKey(id))
                         .set("id", id).build();
         _datastore.put(entity);
     }
 
    
    
     
     /**
      * Remove a session id from the cluster.
      * 
      * @param id
      */
     protected void delete (String id)
     {
         if (_datastore == null)
             throw new IllegalStateException ("No DataStore");
         
         _datastore.delete(makeKey(id));
     }
     
     
 
     /**
      * Generate a unique key from the session id.
      * 
      * @param id
      * @return
      */
     protected Key makeKey (String id)
     {
         return _keyFactory.newKey(id);
     }
 }