/*
    * EL4J, the Extension Library for the J2EE, adds incremental enhancements to
    * the spring framework, http://el4j.sf.net
    * Copyright (C) 2010 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.jpa.dao.extentstrategies;
  
  import java.util.Collection;
  
  import org.apache.commons.collections.map.ReferenceMap;
  import org.hibernate.Hibernate;
  import org.hibernate.proxy.HibernateProxy;
  import org.springframework.dao.DataAccessException;
  
  import ch.elca.el4j.services.persistence.hibernate.dao.extent.ExtentCollection;
  import ch.elca.el4j.services.persistence.hibernate.dao.extent.ExtentEntity;
  
  /**
   * Extent Fetcher for JPA with underlying Hibernate implementation.
   *
   * @svnLink $Revision: 4253 $;$Date: 2010-12-21 11:08:04 +0100 (Di, 21. Dez 2010) $;$Author: swismer $;$URL: https://el4j.svn.sourceforge.net/svnroot/el4j/branches/el4j_3_1/el4j/framework/modules/hibernate/src/main/java/ch/elca/el4j/services/persistence/jpa/dao/extentstrategies/HibernateExtentFetcher.java $
   *
   * @author Simon Stelling (SST)
   */
  public class HibernateExtentFetcher implements ExtentFetcher {
  
  	/** {@inheritDoc} */
  	public void fetchExtentObject(Object object, ExtentEntity entity, ReferenceMap fetchedObjects)
  		throws DataAccessException {
  	
  		Object[] nullArg = null;
  		if (object == null || entity == null || fetchedObjects == null) {
  			return;
  		}
  		fetchedObjects.put(object, entity);
  		try {
  			for (ExtentEntity ent : entity.getChildEntities()) {
  				Object obj = ent.getMethod().invoke(object, nullArg);
  				// Initialize the object if it is a proxy
  				if (obj instanceof HibernateProxy && !Hibernate.isInitialized(obj)) {
  					Hibernate.initialize(obj);
  				}
  				if (!fetchedObjects.containsKey(obj) || !fetchedObjects.get(obj).equals(ent)) {
  					fetchExtentObject(obj, ent, fetchedObjects);
  				}
  			}
  			
  			// Fetch the collections. Since we assume batch fetching for collections
  			for (ExtentCollection c : entity.getCollections()) {
  				Collection<?> coll = (Collection<?>) c.getMethod().invoke(object, nullArg);
  				if (coll != null) {
  					for (Object o : coll) {
  						// Initialize the object if it is a proxy
  						if (o instanceof HibernateProxy && !Hibernate.isInitialized(o)) {
  							Hibernate.initialize(o);
  						}
  						if (!fetchedObjects.containsKey(o) || !fetchedObjects.get(o).equals(c.getContainedEntity())) {
  							fetchExtentObject(o, c.getContainedEntity(), fetchedObjects);
  						}
  					}
  				}
  			}
  		} catch (Exception e) {
  			throw new RuntimeException(e);
  		}
  	
  	}
  	
  }