/*
    * EL4J, the Extension Library for the J2EE, adds incremental enhancements to
    * the spring framework, http://el4j.sf.net
    * Copyright (C) 2009 by ELCA Informatique SA, Av. de la Harpe 22-24,
    * 1000 Lausanne, Switzerland, http://www.elca.ch
    *
    * EL4J is published under the GNU Lesser General Public License (LGPL)
    * Version 2.1. See http://www.gnu.org/licenses/
    *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   * GNU Lesser General Public License for more details.
   *
   * For alternative licensing, please contact info@elca.ch
   */
  package ch.elca.el4j.services.persistence.hibernate;
  
  import java.io.Serializable;
  import java.sql.PreparedStatement;
  import java.sql.SQLException;
  
  import org.hibernate.HibernateException;
  import org.hibernate.dialect.Dialect;
  import org.hibernate.engine.SessionImplementor;
  import org.hibernate.id.AbstractPostInsertGenerator;
  import org.hibernate.id.IdentifierGeneratorHelper;
  import org.hibernate.id.PostInsertIdentityPersister;
  import org.hibernate.id.SequenceIdentityGenerator.NoCommentsInsert;
  import org.hibernate.id.insert.AbstractReturningDelegate;
  import org.hibernate.id.insert.IdentifierGeneratingInsert;
  import org.hibernate.id.insert.InsertGeneratedIdentifierDelegate;
  
  /**
   * A generator with immediate retrieval through JDBC3
   * {@link java.sql.Connection#prepareStatement(String, String[]) getGeneratedKeys}.
   * The value of the identity column must be set from a "before insert trigger"
   * 
   * This generator is tested with Oracle and only known to work with newer Oracle drivers compiled for
   * JDK 1.4 (JDBC3). The minimum version is 10.2.0.1
   * 
   * Note: Due to a bug in Oracle drivers, sql comments on these insert statements
   * are completely disabled.
   *
   * @svnLink $Revision: 4110 $;$Date: 2010-08-04 14:40:16 +0200 (Mi, 04. Aug 2010) $;$Author: swrelca $;$URL: https://el4j.svn.sourceforge.net/svnroot/el4j/branches/el4j_3_1/el4j/framework/modules/hibernate/src/main/java/ch/elca/el4j/services/persistence/hibernate/TriggerAssignedIdentityGenerator.java $
   *
   * @author Jean-Pol Landrain - extern (XYZ)
   * @author Martin Zeltner (MZE)
   */
  public class TriggerAssignedIdentityGenerator extends AbstractPostInsertGenerator {
  	/**
  	 * {@inheritDoc}
  	 */
  	public InsertGeneratedIdentifierDelegate getInsertGeneratedIdentifierDelegate(
  		PostInsertIdentityPersister persister, Dialect dialect, boolean isGetGeneratedKeysEnabled)
  		throws HibernateException {
  		return new Delegate(persister, dialect);
  	}
  
  	/**
  	 * Delegate for the returned generated value.
  	 */
  	public static class Delegate extends AbstractReturningDelegate {
  		/**
  		 * Use database dialect.
  		 */
  		private final Dialect m_dialect;
  
  		/**
  		 * Are the key columns.
  		 */
  		private final String[] m_keyColumns;
  
  		/**
  		 * @param persister Is the post insert identity persister 
  		 * @param dialect Is the dialect of the database.
  		 */
  		public Delegate(PostInsertIdentityPersister persister, Dialect dialect) {
  			super(persister);
  			m_dialect = dialect;
  			m_keyColumns = getPersister().getRootTableKeyColumnNames();
  			if (m_keyColumns.length > 1) {
  				throw new HibernateException(
  					"trigger assigned identity generator cannot be used with multi-column keys");
  			}
  		}
  
  		/**
  		 * Removes the comments for insertion.
  		 * 
  		 * {@inheritDoc}
  		 */
  		public IdentifierGeneratingInsert prepareIdentifierGeneratingInsert() {
  			NoCommentsInsert insert = new NoCommentsInsert(m_dialect);
  			return insert;
  		}
  
  		/**
  		 * {@inheritDoc}
 		 */
 		protected PreparedStatement prepare(String insertSQL, SessionImplementor session) throws SQLException {
 			return session.getBatcher().prepareStatement(insertSQL, m_keyColumns);
 		}
 
 		/**
 		 * {@inheritDoc}
 		 */
 		protected Serializable executeAndExtract(PreparedStatement insert) throws SQLException {
 			insert.executeUpdate();
 			return IdentifierGeneratorHelper.getGeneratedIdentity(
 				insert.getGeneratedKeys(),
 				getPersister().getIdentifierType());
 		}
 	}
 }