/*
    * EL4J, the Extension Library for the J2EE, adds incremental enhancements to
    * the spring framework, http://el4j.sf.net
    * Copyright (C) 2005 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.helper;
  
  import javax.persistence.EntityManager;
  import javax.persistence.EntityNotFoundException;
  import javax.persistence.PersistenceContext;
  
  import org.slf4j.LoggerFactory;
  import org.springframework.transaction.annotation.Transactional;
  
  import ch.elca.el4j.services.persistence.generic.dto.AbstractIntOptimisticLockingDto;
  import ch.elca.el4j.services.persistence.generic.dto.PrimaryKeyObject;
  import ch.elca.el4j.services.persistence.jpa.util.JpaQuery;
  import ch.elca.el4j.services.persistence.jpa.util.QueryException;
  
  /**
   * Implementation of DataService.
   *
   * @svnLink $Revision: 4112 $;$Date: 2010-08-05 11:00:36 +0200 (Do, 05. 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/jpa/helper/JpaHelperImpl.java $
   *
   * @author David Bernhard (dab)
   */
  public class JpaHelperImpl implements JpaHelper {
  
  	/**
  	 * The entity manager.
  	 */
  	@PersistenceContext
  	private EntityManager em;
  	
  	@Override 
  	public <T> JpaQuery<T> selectFrom(Class<T> cls) {
  		return new JpaQuery<T>(cls, this);
  	}
  
  	/**
  	 * Check if an instance is new. 
  	 * @param instance The instance.
  	 * @return true if it is new.
  	 * @throws IllegalArgumentException If the instance is not an entity.
  	 */
  	private boolean isNew(Object instance) throws IllegalArgumentException {
  		// TODO We won't need this once we've changed to a clean JPA
  		// programming model.
  		if (instance instanceof PrimaryKeyObject) {
  			PrimaryKeyObject dto
  				= (PrimaryKeyObject) instance;
  			return dto.isKeyNew();
  		} else {
  			throw new IllegalArgumentException("Cannot persist " + instance
  				+ " : Not an entity, class is "
  				+ instance.getClass().getName());
  		}
  	}
  
  	@Override 
  	@Transactional 
  	public <T> Boolean contains(T instance) {
  		T t = instance;
  		return em.contains(t);
  	}
  	
  	@Override 
  	@Transactional 
  	public <T> T merge(T instance) {
  		T t = instance;
  		if (em.contains(t)) {
  			LoggerFactory.getLogger(this.getClass())
  				.warn("merge is called on a MANAGED entity instead on a DETACHED one.");
  		}
  		t = em.merge(t);
  		return t;
  	}
  	
  	@Override 
  	@Transactional 
  	public <T> void detach(T instance) {
  		T t = instance;
  		if (!em.contains(t)) {
  			LoggerFactory.getLogger(this.getClass())
  				.warn("merge is not called on a MANAGED entity.");
  		}
  		em.detach(t);
  	}
 	
 	@Override 
 	@Transactional 
 	public <T> void persist(T instance) {
 		T t = instance;
 		if (em.contains(t)) {
 			LoggerFactory.getLogger(this.getClass())
 				.warn("persist is called on a MANAGED entity instead on a NEW one.");
 		}
 		em.persist(t);
 	}
 
 	@Override 
 	@Transactional 
 	public <T> void remove(T instance) {
 		T t = instance;
 		if (!em.contains(t)) {
 			LoggerFactory.getLogger(this.getClass()).warn("remove is not called on a MANAGED entity.");
 		}
 		em.remove(t);
 	}
 
 	@Override 
 	@Transactional 
 	public <T> void refresh(T instance) {
 		T t = instance;
 		if (!em.contains(t)) {
 			LoggerFactory.getLogger(this.getClass()).warn("refresh is not called on a MANAGED entity.");
 		}
 		em.refresh(t);
 	}
 
 	@Override
 	@Transactional
 	public <T> T findByKey(Class<T> clazz, Integer key) {
 		T t = em.find(clazz, key);
 		return t;
 	}
 	
 	
 	@Override 
 	public void clear() {
 		em.clear();
 	}
 
 	@Override 
 	@Transactional 
 	public void flush() {
 		em.flush();
 	}
 	
 	/**
 	 * Getter for entity manager.
 	 */
 	public EntityManager getEntityManager() {
 		return em;
 	}
 
 	/**
 	 * Set the entity manager.
 	 * @param em The entity manager.
 	 */
 	public void setEntityManager(EntityManager em) {
 		this.em = em;
 	}
 	
 	@Override 
 	@Transactional 
 	public void doInTransaction(Runnable r) {
 		r.run();
 	}
 }