/*
    * Copyright (c) 2002-2014, Mairie de Paris
    * All rights reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions
    * are met:
    *
    *  1. Redistributions of source code must retain the above copyright notice
   *     and the following disclaimer.
   *
   *  2. Redistributions in binary form must reproduce the above copyright notice
   *     and the following disclaimer in the documentation and/or other materials
   *     provided with the distribution.
   *
   *  3. Neither the name of 'Mairie de Paris' nor 'Lutece' nor the names of its
   *     contributors may be used to endorse or promote products derived from
   *     this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   * License 1.0
   */
  package fr.paris.lutece.util.pool;
  
  import fr.paris.lutece.portal.service.init.LuteceInitException;
  import fr.paris.lutece.util.ReferenceList;
  import fr.paris.lutece.util.pool.service.ConnectionService;
  import fr.paris.lutece.util.pool.service.LuteceConnectionService;
  
  import org.apache.log4j.Logger;
  
  import java.io.InputStream;
  
  import java.sql.Connection;
  
  import java.util.Collection;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.Hashtable;
  import java.util.Map;
  import java.util.Properties;
  
  import javax.sql.DataSource;
  
  
  /**
   * This class can manages a set of database connections pools. It's implemented as a singleton. It provides methods to
   * get or release a connection from a given pool.
   */
  public final class PoolManager
  {
      private static final String LOGGER_NAME = "lutece.pool";
      private static PoolManager _instance;
      private Logger _logger;
      private Map<String, ConnectionService> _pools = new HashMap<String, ConnectionService>(  );
  
      /**
       * Creates a new PoolManager object.
       *
       *
       * @param isDbProperties A properties file containing pools parameters.
       * @throws LuteceInitException If any error occured
       */
      private PoolManager( InputStream isDbProperties ) throws LuteceInitException
      {
          init( isDbProperties );
      }
  
      /**
       * This method returns the unique instance of the PoolManager.
       *
       * @return The unique instance of Poolmanager.
       * @param isDbProperties An InputStream on a db.properties File to initialiaze the pool if it's not already created.
       * @throws LuteceInitException  If any error occured
       */
      public static synchronized PoolManager getInstance( InputStream isDbProperties )
          throws LuteceInitException
      {
          if ( _instance == null )
          {
              _instance = new PoolManager( isDbProperties );
          }
  
          return _instance;
      }
  
      /**
       * Initializes pools with parameters defined in a db.properties File.
      *
      * @param is An InputStream on a db.properties File.
      * @throws LuteceInitException If any error occured
      */
     private void init( InputStream is ) throws LuteceInitException
     {
         _logger = Logger.getLogger( LOGGER_NAME );
 
         Properties dbProps = new Properties(  );
 
         try
         {
             dbProps.load( is );
         }
         catch ( Exception e )
         {
             throw new LuteceInitException( "Can't read the properties file. Make sure db.properties is in the CLASSPATH",
                 e );
         }
 
         createPools( dbProps );
     }
 
     /**
      * Creates all pools defined in a properties file.
      *
      * @param props A properties file containing pools parameters.
      * @throws LuteceInitException  If any error occured
      */
     private void createPools( Properties props ) throws LuteceInitException
     {
         Enumeration propNames = props.propertyNames(  );
         String strPoolName = "";
 
         Hashtable<String, Hashtable<String, String>> htPools = new Hashtable<String, Hashtable<String, String>>(  );
 
         while ( propNames.hasMoreElements(  ) )
         {
             String name = (String) propNames.nextElement(  );
 
             try
             {
                 strPoolName = name.substring( 0, name.lastIndexOf( '.' ) );
 
                 //tests if the pool has yet somme of its porperties stored in the hatsable
                 Hashtable<String, String> htParamsPool;
 
                 //if the pool has not yet property
                 if ( htPools.get( strPoolName ) == null )
                 {
                     htParamsPool = new Hashtable<String, String>(  );
                 }
                 else
                 {
                     htParamsPool = htPools.get( strPoolName );
                 }
 
                 htParamsPool.put( name, props.getProperty( name ) );
                 htPools.put( strPoolName, htParamsPool );
 
                 _logger.debug( "property " + name );
                 _logger.debug( "pool name " + strPoolName );
             }
             catch ( Exception e )
             {
                 throw new LuteceInitException( 
                     "Invalid initialization of the pools. Problem encoutered with the property :  " + name, e );
             }
         }
 
         Enumeration enumKeys = htPools.keys(  );
 
         while ( enumKeys.hasMoreElements(  ) )
         {
             String key = "";
 
             try
             {
                 key = (String) enumKeys.nextElement(  );
 
                 Hashtable<String, String> htParamsPool = htPools.get( key );
                 ConnectionService cs = null;
 
                 try
                 {
                     String strConnectionService = htParamsPool.get( key + ".poolservice" );
 
                     cs = (ConnectionService) Class.forName( strConnectionService ).newInstance(  );
                 }
                 catch ( NullPointerException nullEx )
                 {
                     cs = new LuteceConnectionService(  );
                 }
                 catch ( Exception e )
                 {
                     throw new LuteceInitException( "Exception when getting the property poolservice", e );
                 }
 
                 if ( cs != null )
                 {
                     cs.setPoolName( key );
                     cs.setLogger( _logger );
                     cs.init( htParamsPool );
                     _pools.put( key, cs );
                 }
             }
             catch ( Exception e )
             {
                 throw new LuteceInitException( "Exception when getting the pool '" + key +
                     "'. Please check your '/WEB-INF/conf/db.properties' file.", e );
             }
         }
     }
 
     /**
      * Returns an available connection from the pool.
      *
      * @param strPoolName The pool name
      * @return A connection
      */
     public Connection getConnection( String strPoolName )
     {
         Connection conn = null;
         ConnectionService pool = (ConnectionService) _pools.get( strPoolName );
 
         if ( pool != null )
         {
             conn = pool.getConnection(  );
         }
 
         return conn;
     }
 
     /**
      * Returns a connection to pool.
      *
      * @param strPoolName Pool's name
      * @param con A released connection
      */
     public void freeConnection( String strPoolName, Connection con )
     {
         ConnectionService cs = (ConnectionService) _pools.get( strPoolName );
 
         if ( cs != null )
         {
             cs.freeConnection( con );
         }
     }
 
     /**
      * Releases all connections from all the pool.
      */
     public synchronized void release(  )
     {
         for ( ConnectionService pool : _pools.values(  ) )
         {
             pool.release(  );
         }
     }
 
     /**
      * Returns all pools available
      * @return The list of available pools
      */
     public Collection<ConnectionService> getPools(  )
     {
         return _pools.values(  );
     }
 
     /**
      * Returns pool's infos (currently opened connections)
      * @return The pool's infos
      */
     public ReferenceList getPoolsInfos(  )
     {
         ReferenceList listPoolsInfos = new ReferenceList(  );
         Collection<ConnectionService> listPools = getPools(  );
 
         for ( ConnectionService cs : listPools )
         {
             String strCurrentConnections = ( cs.getCurrentConnections(  ) == cs.INFO_NOT_AVAILABLE ) ? "-"
                                                                                                      : ( "" +
                 cs.getCurrentConnections(  ) );
             String strMaxConnections = ( cs.getMaxConnections(  ) == cs.INFO_NOT_AVAILABLE ) ? "-"
                                                                                              : ( "" +
                 cs.getMaxConnections(  ) );
             listPoolsInfos.addItem( cs.getPoolName(  ),
                 strCurrentConnections + " / " + strMaxConnections + " (" + cs.getPoolProvider(  ) + ")" );
         }
 
         return listPoolsInfos;
     }
 
     /**
      * Returns the datasource for a given pool name
      * @param strPoolName The Pool name
      * @return A data source object
      */
     public DataSource getDataSource( String strPoolName )
     {
         return _pools.get( strPoolName ).getDataSource(  );
     }
 }