/*
    * 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.remoting.jaxb.hibernate;
  
  import java.lang.reflect.Method;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.sun.xml.bind.api.AccessorException;
  import com.sun.xml.bind.v2.runtime.JAXBContextImpl;
  import com.sun.xml.bind.v2.runtime.reflect.Accessor;
  
  /**
   * A JAXB Accessor that replaces uninitialized values by <code>null</code> to avoid LazyInitializationException.
   *
   * @svnLink $Revision: 3945 $;$Date: 2009-10-16 09:31:52 +0200 (Fr, 16. Okt 2009) $;$Author: swismer $;$URL: https://el4j.svn.sourceforge.net/svnroot/el4j/branches/el4j_3_1/el4j/framework/modules/remoting_jaxws/src/main/java/ch/elca/el4j/services/remoting/jaxb/hibernate/HibernateJAXBAccessor.java $
   * 
   * @param <B> the bean type
   * @param <V> the value type
   *
   * @author clemenb (see https://forum.hibernate.org/viewtopic.php?f=1&t=998896)
   */
  public class HibernateJAXBAccessor<B, V> extends Accessor<B, V> {
  
  	/**
  	 * The delegate accessor.
  	 */
  	private Accessor<B, V> delegate;
  	
  	/**
  	 * The method to call for checking if value is uninitialized.
  	 */
  	private final Method hibernateInitializationCheck;
  
  	/**
  	 * @param delegate                        the delegate accessor
  	 * @param hibernateInitializationCheck    the method to call for checking if value is uninitialized
  	 */
  	protected HibernateJAXBAccessor(Accessor<B, V> delegate, Method hibernateInitializationCheck) {
  		super(delegate.getValueType());
  		if (delegate == null) {
  			throw new IllegalArgumentException("delegate must not be null");
  		} else if (hibernateInitializationCheck == null) {
  			throw new IllegalArgumentException("hibernateInitializationCheck must not be null");
  		}
  
  		this.delegate = delegate;
  		this.hibernateInitializationCheck = hibernateInitializationCheck;
  	}
  
  	@Override
  	public Accessor<B, V> optimize(JAXBContextImpl context) {
  		delegate = delegate.optimize(context);
  		return this;
  	}
  
  	@Override
  	public V get(B bean) throws AccessorException {
  		return hideLazy(delegate.get(bean));
  	}
  
  	@Override
  	public void set(B bean, V value) throws AccessorException {
  		delegate.set(bean, value);
  	}
  
  	/**
  	 * @param value    the value to check
  	 * @return         the value if it is initialized, otherwise <code>null</code> 
  	 */
  	protected V hideLazy(V value) {
  		try {
  			boolean isInitialized = (Boolean) hibernateInitializationCheck.invoke(null, new Object[] {value});
  			if (isInitialized) {
  				return value;
  			} else {
  				return null;
  			}
  		} catch (Exception e) {
  			Logger logger = LoggerFactory.getLogger(HibernateJAXBAccessor.class);
  			logger.error("Failed to determine state of Hibernate object or collection, assuming " + value
  				+ " is initialized", e);
  			return null;
  		}
 	}
 }