/*
    * Hibernate, Relational Persistence for Idiomatic Java
    *
    * Copyright (c) 2010, Red Hat Inc. or third-party contributors as
    * indicated by the @author tags or express copyright attribution
    * statements applied by the authors.  All third-party contributions are
    * distributed under license by Red Hat Inc.
    *
    * This copyrighted material is made available to anyone wishing to use, modify,
   * copy, or redistribute it subject to the terms and conditions of the GNU
   * Lesser General Public License, as published by the Free Software Foundation.
   *
   * 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.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with this distribution; if not, write to:
   * Free Software Foundation, Inc.
   * 51 Franklin Street, Fifth Floor
   * Boston, MA  02110-1301  USA
   */
  package org.hibernate.id.factory;
  
  import java.util.Properties;
  import java.io.Serializable;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.hibernate.id.IdentifierGenerator;
  import org.hibernate.id.UUIDGenerator;
  import org.hibernate.id.UUIDHexGenerator;
  import org.hibernate.id.TableHiLoGenerator;
  import org.hibernate.id.Assigned;
  import org.hibernate.id.IdentityGenerator;
  import org.hibernate.id.SelectGenerator;
  import org.hibernate.id.SequenceGenerator;
  import org.hibernate.id.SequenceHiLoGenerator;
  import org.hibernate.id.IncrementGenerator;
  import org.hibernate.id.ForeignGenerator;
  import org.hibernate.id.GUIDGenerator;
  import org.hibernate.id.SequenceIdentityGenerator;
  import org.hibernate.id.Configurable;
  import org.hibernate.id.enhanced.SequenceStyleGenerator;
  import org.hibernate.id.enhanced.TableGenerator;
  import org.hibernate.type.Type;
  import org.hibernate.util.ReflectHelper;
  import org.hibernate.dialect.Dialect;
  import org.hibernate.MappingException;
  
  /**
   * Basic <tt>templated</tt> support for {@link IdentifierGeneratorFactory} implementations.
   *
   * @author Steve Ebersole
   */
  public class DefaultIdentifierGeneratorFactory implements IdentifierGeneratorFactory, Serializable {
  	private static final Logger log = LoggerFactory.getLogger( DefaultIdentifierGeneratorFactory.class );
  
  	private transient Dialect dialect;
  	private ConcurrentHashMap<String, Class> generatorStrategyToClassNameMap = new ConcurrentHashMap<String, Class>();
  
  	/**
  	 * Constructs a new DefaultIdentifierGeneratorFactory.
  	 */
  	public DefaultIdentifierGeneratorFactory() {
  		register( "uuid2", UUIDGenerator.class );
  		register( "guid", GUIDGenerator.class );			// can be done with UUIDGenerator + strategy
  		register( "uuid", UUIDHexGenerator.class );			// "deprecated" for new use
  		register( "uuid.hex", UUIDHexGenerator.class ); 	// uuid.hex is deprecated
  		register( "hilo", TableHiLoGenerator.class );
  		register( "assigned", Assigned.class );
  		register( "identity", IdentityGenerator.class );
  		register( "select", SelectGenerator.class );
  		register( "sequence", SequenceGenerator.class );
  		register( "seqhilo", SequenceHiLoGenerator.class );
  		register( "increment", IncrementGenerator.class );
  		register( "foreign", ForeignGenerator.class );
  		register( "sequence-identity", SequenceIdentityGenerator.class );
  		register( "enhanced-sequence", SequenceStyleGenerator.class );
  		register( "enhanced-table", TableGenerator.class );
  	}
  
  	/**
  	 * {@inheritDoc}
  	 */
  	public void setDialect(Dialect dialect) {
  		log.debug( "Setting dialect [" + dialect + "]" );
  		this.dialect = dialect;
  	}
  
  	public void register(String strategy, Class generatorClass) {
  		String msg = "Registering IdentifierGenerator strategy [" + strategy + "] -> [" + generatorClass + "]";
  		Object old = generatorStrategyToClassNameMap.put( strategy, generatorClass );
  		if ( old != null ) {
  			msg += ", overriding [" + old + "]";
  		}
 		log.debug( msg );
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public IdentifierGenerator createIdentifierGenerator(String strategy, Type type, Properties config) {
 		try {
 			Class clazz = getIdentifierGeneratorClass( strategy );
 			IdentifierGenerator idgen = ( IdentifierGenerator ) clazz.newInstance();
 			if ( idgen instanceof Configurable ) {
 				( ( Configurable ) idgen ).configure( type, config, dialect );
 			}
 			return idgen;
 		}
 		catch ( Exception e ) {
 			String msg = "Could not instantiate id generator [entity-name="
 					+ config.get( IdentifierGenerator.ENTITY_NAME ) + "]";
 			throw new MappingException( msg, e );
 		}
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public Class getIdentifierGeneratorClass(String strategy) {
 		if ( "native".equals( strategy ) ) {
 			return dialect.getNativeIdentifierGeneratorClass();
 		}
 
 		Class generatorClass = generatorStrategyToClassNameMap.get( strategy );
 		try {
 			if ( generatorClass == null ) {
 				generatorClass = ReflectHelper.classForName( strategy );
 			}
 		}
 		catch ( ClassNotFoundException e ) {
 			throw new MappingException( "Could not interpret id generator strategy [" + strategy + "]" );
 		}
 		return generatorClass;
 	}
 }