/*
    * 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.portal.service.cache;
  
  import fr.paris.lutece.portal.service.util.AppLogService;
  
  import net.sf.ehcache.Cache;
  import net.sf.ehcache.CacheException;
  import net.sf.ehcache.Ehcache;
  import net.sf.ehcache.Element;
  import net.sf.ehcache.Statistics;
  import net.sf.ehcache.event.CacheEventListener;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  /**
   * Base implementation for a cacheable service
   */
  public abstract class AbstractCacheableService implements CacheableService, CacheEventListener
  {
      private Cache _cache;
      private boolean _bEnable;
      private Logger _logger = LogManager.getLogger( "lutece.cache" );
  
      /**
       * Init the cache. Should be called by the service at its initialization.
       */
      public void initCache( )
      {
          initCache( getName( ) );
      }
  
      /**
       * Init the cache. Should be called by the service at its initialization.
       * 
       * @param strCacheName
       *            The cache name
       */
      public void initCache( String strCacheName )
      {
          createCache( strCacheName );
          _bEnable = true;
          CacheService.registerCacheableService( this );
      }
  
      /**
       * Create a cache
       * 
       * @param strCacheName
       *            The cache name
       */
      private void createCache( String strCacheName )
      {
          _cache = CacheService.getInstance( ).createCache( strCacheName );
          _cache.getCacheEventNotificationService( ).registerListener( this );
      }
  
      /**
       * Put an object into the cache
       * 
       * @param strKey
       *            The key of the object to put into the cache
       * @param object
       *            The object to put into the cache
      */
     public void putInCache( String strKey, Object object )
     {
         if ( ( _cache != null ) && isCacheEnable( ) )
         {
             Element element = new Element( strKey, object );
             _cache.put( element );
         }
     }
 
     /**
      * Gets an object from the cache
      * 
      * @param strKey
      *            The key of the object to retrieve from the cache
      * @return The object from the cache
      */
     public Object getFromCache( String strKey )
     {
         Object object = null;
 
         if ( ( _cache != null ) && isCacheEnable( ) )
         {
             Element element = _cache.get( strKey );
 
             if ( element != null )
             {
                 object = element.getObjectValue( );
             }
         }
 
         return object;
     }
 
     /**
      * Gets the current cache status.
      *
      * @return true if enable, otherwise false
      */
     @Override
     public boolean isCacheEnable( )
     {
         return _bEnable;
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public void enableCache( boolean bEnable )
     {
         _bEnable = bEnable;
 
         if ( ( !_bEnable ) && ( _cache != null ) )
         {
             _cache.removeAll( );
         }
 
         if ( ( _bEnable ) && ( _cache == null ) )
         {
             createCache( getName( ) );
         }
 
         CacheService.updateCacheStatus( this );
     }
 
     /**
      * Reset the cache.
      */
     @Override
     public void resetCache( )
     {
         try
         {
             if ( _cache != null )
             {
                 _cache.removeAll( );
             }
         }
         catch( CacheException | IllegalStateException e )
         {
             AppLogService.error( e.getMessage( ), e );
         }
     }
 
     /**
      * Gets the number of item currently in the cache.
      *
      * @return the number of item currently in the cache.
      */
     @Override
     public int getCacheSize( )
     {
         return ( _cache != null ) ? _cache.getSize( ) : 0;
     }
 
     /**
      * Return a cache object
      * 
      * @return cache object
      */
     public Cache getCache( )
     {
         return _cache;
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public List<String> getKeys( )
     {
         if ( _cache != null )
         {
             return _cache.getKeys( );
         }
 
         return new ArrayList<>( );
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public int getMaxElements( )
     {
         return _cache.getCacheConfiguration( ).getMaxElementsInMemory( );
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public long getTimeToLive( )
     {
         return _cache.getCacheConfiguration( ).getTimeToLiveSeconds( );
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public long getMemorySize( )
     {
         return _cache.calculateInMemorySize( );
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public String getInfos( )
     {
         return CacheService.getInfos( _cache );
     }
 
     /**
      * Get cache statistics.
      * 
      * The string representation is susceptible to change
      * 
      * @return a string representation of cache statistics
      * 
      * @since 7.0.10
      */
     public String getStatistics( )
     {
         if ( !( isCacheEnable( ) && _cache.getCacheConfiguration( ).getStatistics( ) ) )
         {
             return null;
         }
         Statistics stats = _cache.getStatistics( );
         StringBuilder buidler = new StringBuilder( );
         buidler.append( "name = " ).append( stats.getAssociatedCacheName( ) ).append( "\ncacheHits = " )
                 .append( stats.getCacheHits( ) ).append( "\nonDiskHits = " ).append( stats.getOnDiskHits( ) )
                 .append( "\noffHeapHits = " ).append( stats.getOffHeapHits( ) ).append( "\ninMemoryHits = " )
                 .append( stats.getInMemoryHits( ) ).append( "\nmisses = " ).append( stats.getCacheMisses( ) )
                 .append( "\nonDiskMisses = " ).append( stats.getOnDiskMisses( ) ).append( "\noffHeapMisses = " )
                 .append( stats.getOffHeapMisses( ) ).append( "\ninMemoryMisses = " )
                 .append( stats.getInMemoryMisses( ) ).append( "\nsize = " ).append( stats.getObjectCount( ) )
                 .append( "\naverageGetTime = " ).append( stats.getAverageGetTime( ) ).append( "\nevictionCount = " )
                 .append( stats.getEvictionCount( ) );
         return buidler.toString( );
     }
 
     // CacheEventListener implementation
 
     /**
      * @see java.lang.Object#clone()
      * @return the instance
      */
     @Override
     public Object clone( )
     {
         throw new UnsupportedOperationException( "This class shouldn't be cloned" );
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public void notifyElementExpired( Ehcache cache, Element element )
     {
         // Remove the element from the cache
         _cache.remove( element.getKey( ) );
         _logger.debug( "Object removed from the cache : {}  - key : {}", cache.getName( ), element.getKey( ) );
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public void notifyElementRemoved( Ehcache ehch, Element elmnt )
     {
         // Do nothing
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public void notifyElementEvicted( Ehcache ehch, Element elmnt )
     {
         // Do nothing
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public void notifyRemoveAll( Ehcache ehch )
     {
         // Do nothing
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public void notifyElementPut( Ehcache ehch, Element elmnt )
     {
         // Do nothing
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public void notifyElementUpdated( Ehcache ehch, Element elmnt )
     {
         // Do nothing
     }
 
     /**
      * {@inheritDoc }
      */
     @Override
     public void dispose( )
     {
         // Do nothing
     }
 
     /**
      * Remove a key from the cache
      * 
      * @param strKey
      *            The key to remove
      */
     public void removeKey( String strKey )
     {
         getCache( ).remove( strKey );
     }
 }