/*
    *  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.api.sp;
  
  
  import java.util.List;
  
  import javax.naming.directory.SearchControls;
  
  import org.apache.directory.api.ldap.model.constants.SchemaConstants;
  import org.apache.directory.api.ldap.model.cursor.Cursor;
  import org.apache.directory.api.ldap.model.entry.Entry;
  import org.apache.directory.api.ldap.model.entry.Value;
  import org.apache.directory.api.ldap.model.exception.LdapException;
  import org.apache.directory.api.ldap.model.filter.EqualityNode;
  import org.apache.directory.api.ldap.model.filter.ExprNode;
  import org.apache.directory.api.ldap.model.message.AliasDerefMode;
  import org.apache.directory.api.ldap.model.message.SearchScope;
  import org.apache.directory.api.ldap.model.name.Dn;
  import org.apache.directory.api.ldap.model.schema.AttributeType;
  import org.apache.directory.server.core.api.CoreSession;
  import org.apache.directory.server.core.api.entry.ClonedServerEntry;
  import org.apache.directory.server.i18n.I18n;
  
  
  /**
   * A Factory type class which holds a registry of supported {@link StoredProcEngineConfig}s. A container reference
   * as the base for Stored Procedure storage on the DIT is also handled by this class.
   * 
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public class StoredProcExecutionManager
  {
      private final String storedProcContainer;
  
      private final List<StoredProcEngineConfig> storedProcEngineConfigs;
  
  
      /**
       * Creates a {@link StoredProcExecutionManager} instance.
       * 
       * @param storedProcContainer The base of the DIT subtree used for storing stored procedure units.
       * @param storedProcEngineConfigs A list of {@link StoredProcEngineConfig}s to register different {@link StoredProcEngine}s with this manager.
       */
      public StoredProcExecutionManager( final String storedProcContainer,
          final List<StoredProcEngineConfig> storedProcEngineConfigs )
      {
          this.storedProcContainer = storedProcContainer;
          this.storedProcEngineConfigs = storedProcEngineConfigs;
      }
  
  
      /**
       * Finds and returns a stored procedure unit entry whose identifier name
       * is extracted from fullSPName.
       * 
       * @param session the session with a core directory service
       * @param fullSPName Full name of the Stored Procedure including the unit name.
       * @return The entry associated with the SP Unit.
       * @throws Exception If the unit cannot be located or any other error occurs.
       */
      public Entry findStoredProcUnit( CoreSession session, String fullSPName ) throws Exception
      {
          SearchControls controls = new SearchControls();
          controls.setReturningAttributes( SchemaConstants.ALL_USER_ATTRIBUTES_ARRAY );
          controls.setSearchScope( SearchControls.SUBTREE_SCOPE );
          String spUnitName = StoredProcUtils.extractStoredProcUnitName( fullSPName );
  
          AttributeType storeProcUnitNamAT = session.getDirectoryService()
              .getSchemaManager().lookupAttributeTypeRegistry( "storedProcUnitName" );
          ExprNode filter = new EqualityNode<String>( storeProcUnitNamAT,
              new Value( storeProcUnitNamAT, spUnitName ) );
          Dn dn = session.getDirectoryService().getDnFactory().create( storedProcContainer );
          Cursor<Entry> results = session.search( dn, SearchScope.SUBTREE, filter,
              AliasDerefMode.DEREF_ALWAYS );
          
          if ( results.first() )
          {
              Entry entry = results.get();
              results.close();
  
              return entry;
         }
 
         return null;
     }
 
 
     /**
      * Initializes and returns a {@link StoredProcEngine} instance which can operate on spUnitEntry
      * considering its specific stored procedure language.
      * 
      * @param spUnitEntry The entry which a {@link StoredProcEngine} type will be mathched with respect to the language identifier.
      * @return A {@link StoredProcEngine} associated with spUnitEntry.
      * @throws org.apache.directory.api.ldap.model.exception.LdapException If no {@link StoredProcEngine} that can be associated with the language identifier in spUnitEntry can be found.
      */
     public StoredProcEngine getStoredProcEngineInstance( Entry spUnitEntry ) throws LdapException
     {
         String spLangId = ( ( ClonedServerEntry ) spUnitEntry ).getOriginalEntry().get( "storedProcLangId" )
             .getString();
 
         for ( StoredProcEngineConfig engineConfig : storedProcEngineConfigs )
         {
             if ( engineConfig.getStoredProcLangId().equalsIgnoreCase( spLangId ) )
             {
                 Class<? extends StoredProcEngine> engineType = engineConfig.getStoredProcEngineType();
                 StoredProcEngine engine;
 
                 try
                 {
                     engine = engineType.newInstance();
                 }
                 catch ( InstantiationException | IllegalAccessException e )
                 {
                     LdapException ne = new LdapException( e.getMessage(), e );
                     ne.initCause( e );
                     throw ne;
                 }
 
                 engine.setSPUnitEntry( ( Entry ) ( ( ClonedServerEntry ) spUnitEntry ).getOriginalEntry() );
                 return engine;
             }
 
         }
 
         throw new LdapException( I18n.err( I18n.ERR_294, spLangId ) );
 
     }
 
 }