/*
    * Copyright 2010 James Pether Sörling
    *
    * 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.
   *
   *	$Id$
   *  $HeadURL$
  */
  package com.hack23.cia.service.data.impl.util;
  
  import java.beans.PropertyDescriptor;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.UndeclaredThrowableException;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.IdentityHashMap;
  import java.util.Set;
  
  import org.apache.commons.beanutils.PropertyUtils;
  import org.hibernate.Hibernate;
  import org.hibernate.collection.spi.PersistentCollection;
  import org.hibernate.proxy.HibernateProxy;
  
  /**
   * The Class LoadHelper.
   */
  public final class LoadHelper {
  
  	/**
  	 * Instantiates a new load helper.
  	 */
  	private LoadHelper() {
  		super();
  	}
  
  	/**
  	 * Handle reflection exception.
  	 *
  	 * @param ex
  	 *            the ex
  	 */
  	private static void handleReflectionException(final Exception ex) {
  		if (ex instanceof NoSuchMethodException) {
  			throw new IllegalStateException("Method not found: " + ex.getMessage());
  		}
  		if (ex instanceof IllegalAccessException) {
  			throw new IllegalStateException("Could not access method: " + ex.getMessage());
  		}
  		if (ex instanceof RuntimeException) {
  			throw (RuntimeException) ex;
  		}
  		throw new UndeclaredThrowableException(ex);
  	}
  
  	/**
  	 * Recursive initliaze.
  	 *
  	 * @param obj
  	 *            the obj
  	 * @param dejaVu
  	 *            the deja vu
  	 * @throws IllegalAccessException
  	 *             the illegal access exception
  	 * @throws InvocationTargetException
  	 *             the invocation target exception
  	 * @throws NoSuchMethodException
  	 *             the no such method exception
  	 */
  	private static void recursiveInitialize(final Object obj, final Set<Object> dejaVu)
  			throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
  		if (dejaVu.contains(obj)) {
  			return;
  		} else {
  			dejaVu.add(obj);
  
  			if (!Hibernate.isInitialized(obj)) {
  				Hibernate.initialize(obj);
  			}
  
  			if (obj instanceof HibernateProxy || obj instanceof PersistentCollection) {
  
  				initProxyAndCollections(obj, PropertyUtils.getPropertyDescriptors(obj), dejaVu);
  			}
  		}
  	}
  
  	/**
  	 * Inits the proxy and collections.
  	 *
 	 * @param obj
 	 *            the obj
 	 * @param properties
 	 *            the properties
 	 * @param dejaVu
 	 *            the deja vu
 	 * @throws IllegalAccessException
 	 *             the illegal access exception
 	 * @throws InvocationTargetException
 	 *             the invocation target exception
 	 * @throws NoSuchMethodException
 	 *             the no such method exception
 	 */
 	private static void initProxyAndCollections(final Object obj, final PropertyDescriptor[] properties,
 			final Set<Object> dejaVu) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
 		for (final PropertyDescriptor propertyDescriptor : properties) {
 			if (PropertyUtils.getReadMethod(propertyDescriptor) != null) {
 				initProxies(dejaVu, PropertyUtils.getProperty(obj, propertyDescriptor.getName()));
 			}
 		}
 	}
 
 	/**
 	 * Inits the proxies.
 	 *
 	 * @param dejaVu
 	 *            the deja vu
 	 * @param origProp
 	 *            the orig prop
 	 * @throws IllegalAccessException
 	 *             the illegal access exception
 	 * @throws InvocationTargetException
 	 *             the invocation target exception
 	 * @throws NoSuchMethodException
 	 *             the no such method exception
 	 */
 	private static void initProxies(final Set<Object> dejaVu, final Object origProp)
 			throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
 		if (origProp != null) {
 			recursiveInitialize(origProp, dejaVu);
 		}
 		if (origProp instanceof Collection) {
 			for (final Object item : (Collection<?>) origProp) {
 				recursiveInitialize(item, dejaVu);
 			}
 		}
 	}
 
 	/**
 	 * Recursive initliaze.
 	 *
 	 * @param <T>
 	 *            the generic type
 	 * @param obj
 	 *            the obj
 	 * @return the t
 	 */
 	public static <T> T recursiveInitialize(final T obj) {
 		if (obj != null) {
 
 			final Set<Object> dejaVu = Collections.newSetFromMap(new IdentityHashMap<Object, Boolean>());
 			try {
 				recursiveInitialize(obj, dejaVu);
 			} catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
 				handleReflectionException(e);
 			}
 		}
 		return obj;
 	}
 
 }