/*
 * Copyright 2004-2008 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 org.codehaus.groovy.grails.orm.hibernate.proxy;

import java.lang.reflect.InvocationTargetException;

import org.apache.commons.beanutils.PropertyUtils;
import org.codehaus.groovy.grails.support.proxy.ProxyHandler;
import org.hibernate.Hibernate;
import org.hibernate.collection.AbstractPersistentCollection;
import org.hibernate.collection.PersistentCollection;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.proxy.LazyInitializer;

/**
 * Implementation of the ProxyHandler interface for Hibernate
 * 
 * @author Graeme Rocher
 * @since 1.2.2
 */
public class HibernateProxyHandler implements ProxyHandler {

	public boolean isInitialized(Object o) {
		if(o instanceof HibernateProxy) {
			return !((HibernateProxy)o).getHibernateLazyInitializer().isUninitialized();
		}
		else if(o instanceof PersistentCollection) {
			return ((PersistentCollection)o).wasInitialized();
		}
		return true;
	}

	public boolean isInitialized(Object obj, String associationName) {
        try {
            Object proxy = PropertyUtils.getProperty(obj, associationName);
            return Hibernate.isInitialized(proxy);
        }
        catch (IllegalAccessException e) {
            return false;
        }
        catch (InvocationTargetException e) {
            return false;
        }
        catch (NoSuchMethodException e) {
            return false;
        }
	}

	public Object unwrapIfProxy(Object instance) {
        if(instance instanceof HibernateProxy) {
            final HibernateProxy proxy = (HibernateProxy)instance;
			return unwrapProxy(proxy);
        }
        else if(instance instanceof AbstractPersistentCollection) {
        	initialize(instance);
        	return instance;
        }
        else {
            return instance;
        }
	}

	public Object unwrapProxy(final HibernateProxy proxy) {
		final LazyInitializer lazyInitializer = proxy.getHibernateLazyInitializer();
		if(lazyInitializer.isUninitialized()) {
		    lazyInitializer.initialize();
		}
		return lazyInitializer.getImplementation();
	}
	
	public HibernateProxy getAssociationProxy(Object obj, String associationName) {
        try {
            Object proxy = PropertyUtils.getProperty(obj, associationName);
            if(proxy instanceof HibernateProxy) return (HibernateProxy) proxy;
            else return null;
        }
        catch (IllegalAccessException e) {
            return null;
        }
        catch (InvocationTargetException e) {
            return null;
        }
        catch (NoSuchMethodException e) {
            return null;
        }
	}

	public boolean isProxy(Object o) {
		return (o instanceof HibernateProxy) || (o instanceof AbstractPersistentCollection);
	}

	public void initialize(Object o) {
		if(o instanceof HibernateProxy) {
			final LazyInitializer hibernateLazyInitializer = ((HibernateProxy)o).getHibernateLazyInitializer();
			if(hibernateLazyInitializer.isUninitialized())
				hibernateLazyInitializer.initialize();
		}
		else if(o instanceof AbstractPersistentCollection) {
			final AbstractPersistentCollection col = (AbstractPersistentCollection)o;
			if(!col.wasInitialized())
				col.forceInitialization();
		}		
	}

}
