/*
    *   Licensed to the Apache Software Foundation (ASF) under one
    *   or more contributor license agreements.  See the NOTICE file
    *   distributed with this work for additional information
    *   regarding copyright ownership.  The ASF licenses this file
    *   to you under the Apache License, Version 2.0 (the
    *   "License"); you may not use this file except in compliance
    *   with the License.  You may obtain a copy of the License at
    *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   *   Unless required by applicable law or agreed to in writing,
   *   software distributed under the License is distributed on an
   *   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   *   KIND, either express or implied.  See the License for the
   *   specific language governing permissions and limitations
   *   under the License.
   *
   */
  
  package org.apache.directory.server.core.shared;
  
  
  import java.time.Duration;
  
  import org.apache.directory.api.ldap.model.exception.LdapInvalidDnException;
  import org.apache.directory.api.ldap.model.name.Dn;
  import org.apache.directory.api.ldap.model.schema.SchemaManager;
  import org.apache.directory.server.core.api.DnFactory;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.github.benmanes.caffeine.cache.Cache;
  import com.github.benmanes.caffeine.cache.Caffeine;
  
  
  /**
   * The default Dn factory implementation.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class DefaultDnFactory implements DnFactory
  {
      private static final Logger LOG = LoggerFactory.getLogger( DefaultDnFactory.class );
  
      /** The cache for DNs */
      private Cache<String, Dn> dnCache;
  
      /** The schema manager */
      private SchemaManager schemaManager;
  
      /** Flag to enable stats */
      private boolean enableStats = false;
  
      // stat counters
      private int hitCount = 0;
      private int missCount = 0;
  
  
      /**
       * Instantiates a new default Dn factory.
       *
       * @param schemaManager The SchemaManager instance
       * @param cacheSize The cache size used to store DNs
       */
      public DefaultDnFactory( SchemaManager schemaManager, int cacheSize )
      {
          this.schemaManager = schemaManager;
          this.dnCache = Caffeine.newBuilder().maximumSize( cacheSize ).expireAfterAccess( Duration.ofMinutes( 10L ) )
              .build();
      }
  
  
      /**
       * {@inheritDoc}
       */
      @Override
      public Dn create( String dn ) throws LdapInvalidDnException
      {
          if ( dn == null )
          {
              return null;
          }
  
          if ( dn.trim().length() == 0 )
          {
              return Dn.ROOT_DSE;
          }
  
          Dn cachedDn = null;
  
          // read the explanation at the above DN_CACHE variable declaration
          // for the reason for performing this check
          if ( dnCache != null )
          {
              cachedDn = dnCache.getIfPresent( dn );
          }
  
          if ( cachedDn == null )
         {
             LOG.debug( "Dn {} not found in the cache, creating", dn );
 
             cachedDn = new Dn( schemaManager, dn );
 
             if ( dnCache != null )
             {
                 dnCache.put( dn, cachedDn );
             }
 
             if ( enableStats )
             {
                 missCount++;
             }
         }
         else
         {
             if ( enableStats )
             {
                 hitCount++;
             }
         }
 
         LOG.debug( "Dn {} found in the cache", dn );
 
         if ( enableStats )
         {
             LOG.debug( "Dn cache hit - {} , miss - {} and is normalized = {}", hitCount, missCount, cachedDn.isSchemaAware() );
         }
 
         return cachedDn;
     }
 
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Dn create( String... upRdns ) throws LdapInvalidDnException
     {
         StringBuilder sb = new StringBuilder();
         boolean isFirst = true;
         
         for ( String s : upRdns )
         {
             if ( isFirst )
             {
                 isFirst = false;
             }
             else
             {
                 sb.append( ',' );
             }
             
             sb.append( s );
         }
 
         String dn = sb.toString();
         
         return create( dn );
     }
 
 }