/*
    * Copyright 2002-2007 the original author or authors.
    *
    * Licensed 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 ch.elca.el4j.services.persistence.hibernate.dao;
  
  import java.beans.PropertyDescriptor;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.hibernate.SessionFactory;
  import org.springframework.beans.BeansException;
  import org.springframework.beans.factory.config.BeanPostProcessor;
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.ApplicationContextAware;
  import org.springframework.core.Ordered;
  import org.springframework.core.PriorityOrdered;
  
  import ch.elca.el4j.services.persistence.generic.dao.GenericDao;
  import ch.elca.el4j.util.codingsupport.Reject;
  
  /**
   * Inject the session factory in GenericDaos (or other daos) if needed.
   *  It gets the sessionFactory from the spring context
   *   by using the default name {@link SESSION_FACTORY_BEAN_DEFAULT_NAME} or
   *   via its setter method.
   *
   * @svnLink $Revision: 3875 $;$Date: 2009-08-04 14:35:53 +0200 (Di, 04. Aug 2009) $;$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/hibernate/dao/HibernateSessionFactoryInjectorBeanPostProcessor.java $
   *
   * @author Philipp Oser (POS)
   */
  public class HibernateSessionFactoryInjectorBeanPostProcessor
  		implements BeanPostProcessor, PriorityOrdered, ApplicationContextAware {
  
  	private static final Logger s_logger= LoggerFactory.getLogger(HibernateSessionFactoryInjectorBeanPostProcessor.class);
  
  	/**
  	 * The default name for the property of the session factory.
  	 */
  	public static final String SESSION_FACTORY_BEAN_DEFAULT_NAME = "sessionFactory";
  	
  	private int order = Ordered.LOWEST_PRECEDENCE;
  		
  
  	/**
  	 * Initiates the real work.
  	 */
  	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
  		s_logger.debug("Treating bean with name:" + beanName);
  		if (GenericDao.class.isAssignableFrom(bean.getClass())) {
  			s_logger.debug("init dao with name:" + beanName);
  			initDao((GenericDao<?>) bean);
  		}
  		return bean;
  	}
  
  	/** {@inheritDoc} */
  	public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
  		return bean;
  	}
  
  
  	/**
  	 * Try to init the sessionFactory of the bean.
  	 * @param dao
  	 */
  	protected void initDao(GenericDao<?> dao) {
  		if (getSessionFactory() != null) {
  			try {
  				PropertyDescriptor pd = new PropertyDescriptor(SESSION_FACTORY_BEAN_DEFAULT_NAME,
  					dao.getClass());
  				Object value = pd.getReadMethod().invoke(dao);
  				if (value == null) {
  					pd.getWriteMethod().invoke(dao, m_sessionFactory);
  				}
  				s_logger.debug("value set in dao set");
  			} catch (Exception e) {
  				// ignore problems
  				s_logger.info("problem when auto-setting sessionFactory", e);
  
  			}
  		}
  	}
  
  	
  	
  	/**
 	 * Gets the session factory (from spring context if needed).
 	 * @return
 	 */
 	public SessionFactory getSessionFactory() {
 		if ((m_sessionFactory == null) && (m_applicationContext != null)) {
 			// try to locate the session factory
 			if (m_applicationContext.containsBean(SESSION_FACTORY_BEAN_DEFAULT_NAME)) {
 				m_sessionFactory = (SessionFactory)
 					m_applicationContext.getBean(SESSION_FACTORY_BEAN_DEFAULT_NAME);
 				Reject.ifNull(m_sessionFactory, "session factory must not be null!");
 			}
 		}
 		return m_sessionFactory;
 	}
 
 	/**
 	 * You can either set the session factory explicitly or
 	 *  have the factory load the session factory implicitly (by name).
 	 * @param factory
 	 */
 	public void setSessionFactory(SessionFactory factory) {
 		m_sessionFactory = factory;
 	}
 
 	protected SessionFactory m_sessionFactory;
 
 	private ApplicationContext m_applicationContext;
 
 	public void setOrder(int order) {
 		this.order = order;
 	}
 
 	/** {@inheritDoc} */
 	public int getOrder() {
 		return this.order;
 	}
 
 	/** {@inheritDoc} */
 	public void setApplicationContext(ApplicationContext applicationContext)
 		throws BeansException {
 		
 		m_applicationContext = applicationContext;
 	}
 }