/*
    * Copyright (c) 2002-2022, City of 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 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.Map.Entry;
  import java.util.Properties;
  
  import javax.sql.DataSource;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  import fr.paris.lutece.portal.service.init.LuteceInitException;
  import fr.paris.lutece.portal.service.util.AppPropertiesService;
  import fr.paris.lutece.util.ReferenceList;
  import fr.paris.lutece.util.pool.service.ConnectionService;
  import fr.paris.lutece.util.pool.service.LuteceConnectionService;
  
  /**
   * 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<>( );
  
      /**
       * 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 = LogManager.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 );
         }
         
         overrideProperties(dbProps);       
         createPools( dbProps );
     }
 
     /**
      * Override properties with the api config
      * @param dbProps the database properties 
      */
 	private void overrideProperties(Properties dbProps) {
 		Enumeration propertiesName=  dbProps.propertyNames();
         while (propertiesName.hasMoreElements()) {
         	 String key = (String) propertiesName.nextElement();
         	 String value= AppPropertiesService.getProperty(key);
         	 if( value != null ) {
         		 dbProps.put(key, value);
         	 }
         }
 	}
 
     /**
      * 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 = "";
 
         Map<String, Hashtable<String, String>> htPools = new HashMap<>( );
 
         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 = htPools.computeIfAbsent( strPoolName, s -> new Hashtable<>( ) );
                 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 );
             }
         }
 
         for ( Entry<String, Hashtable<String, String>> entry : htPools.entrySet( ) )
         {
             String key = entry.getKey( );
             try
             {
                 Hashtable<String, String> htParamsPool = htPools.get( key );
                 ConnectionService cs = getConnectionService( htParamsPool, key );
 
                 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 );
             }
         }
     }
 
     private ConnectionService getConnectionService( Map<String, String> htParamsPool, String key ) throws LuteceInitException
     {
         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 );
         }
         return cs;
     }
 
     /**
      * 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 = _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 = _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( )
     {
         ReferenceListReferenceList">ReferenceList listPoolsInfos = new ReferenceList( );
         Collection<ConnectionService> listPools = getPools( );
 
         for ( ConnectionService cs : listPools )
         {
             String strCurrentConnections = ( cs.getCurrentConnections( ) == ConnectionService.INFO_NOT_AVAILABLE ) ? "-" : ( "" + cs.getCurrentConnections( ) );
             String strMaxConnections = ( cs.getMaxConnections( ) == ConnectionService.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( );
     }
 }