/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008-2011, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.event.internal;

import java.io.Serializable;

import org.jboss.logging.Logger;

import org.hibernate.HibernateException;
import org.hibernate.cache.spi.CacheKey;
import org.hibernate.collection.spi.PersistentCollection;
import org.hibernate.engine.spi.PersistenceContext;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.event.spi.InitializeCollectionEvent;
import org.hibernate.event.spi.InitializeCollectionEventListener;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.cache.spi.entry.CollectionCacheEntry;
import org.hibernate.engine.spi.CollectionEntry;
import org.hibernate.persister.collection.CollectionPersister;
import org.hibernate.pretty.MessageHelper;

/**
 * @author Gavin King
 */
public class DefaultInitializeCollectionEventListener implements InitializeCollectionEventListener {

    private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class,
                                                                       DefaultInitializeCollectionEventListener.class.getName());

	/**
	 * called by a collection that wants to initialize itself
	 */
	public void onInitializeCollection(InitializeCollectionEvent event)
	throws HibernateException {

		PersistentCollection collection = event.getCollection();
		SessionImplementor source = event.getSession();

		CollectionEntry ce = source.getPersistenceContext().getCollectionEntry(collection);
		if (ce==null) throw new HibernateException("collection was evicted");
		if ( !collection.wasInitialized() ) {
            if (LOG.isTraceEnabled()) LOG.trace("Initializing collection "
                                                + MessageHelper.collectionInfoString(ce.getLoadedPersister(),
                                                                                     ce.getLoadedKey(),
                                                                                     source.getFactory()));

            LOG.trace("Checking second-level cache");
			final boolean foundInCache = initializeCollectionFromCache(
					ce.getLoadedKey(),
					ce.getLoadedPersister(),
					collection,
					source
				);

            if (foundInCache) LOG.trace("Collection initialized from cache");
			else {
                LOG.trace("Collection not cached");
				ce.getLoadedPersister().initialize( ce.getLoadedKey(), source );
                LOG.trace("Collection initialized");

				if ( source.getFactory().getStatistics().isStatisticsEnabled() ) {
					source.getFactory().getStatisticsImplementor().fetchCollection(
							ce.getLoadedPersister().getRole()
						);
				}
			}
		}
	}

	/**
	 * Try to initialize a collection from the cache
	 *
	 * @param id The id of the collection of initialize
	 * @param persister The collection persister
	 * @param collection The collection to initialize
	 * @param source The originating session
	 * @return true if we were able to initialize the collection from the cache;
	 * false otherwise.
	 */
	private boolean initializeCollectionFromCache(
			Serializable id,
			CollectionPersister persister,
			PersistentCollection collection,
			SessionImplementor source) {

		if ( !source.getEnabledFilters().isEmpty() && persister.isAffectedByEnabledFilters( source ) ) {
            LOG.trace("Disregarding cached version (if any) of collection due to enabled filters");
			return false;
		}

		final boolean useCache = persister.hasCache() &&
				source.getCacheMode().isGetEnabled();

        if (!useCache) return false;

        final SessionFactoryImplementor factory = source.getFactory();

        final CacheKey ck = source.generateCacheKey( id, persister.getKeyType(), persister.getRole() );
        Object ce = persister.getCacheAccessStrategy().get(ck, source.getTimestamp());

		if ( factory.getStatistics().isStatisticsEnabled() ) {
            if (ce == null) {
                factory.getStatisticsImplementor()
						.secondLevelCacheMiss( persister.getCacheAccessStrategy().getRegion().getName() );
            }
			else {
                factory.getStatisticsImplementor()
						.secondLevelCacheHit( persister.getCacheAccessStrategy().getRegion().getName() );
            }
		}

        if ( ce == null ) {
			return false;
		}

		CollectionCacheEntry cacheEntry = (CollectionCacheEntry)persister.getCacheEntryStructure().destructure(ce, factory);

		final PersistenceContext persistenceContext = source.getPersistenceContext();
        cacheEntry.assemble(collection, persister, persistenceContext.getCollectionOwner(id, persister));
        persistenceContext.getCollectionEntry(collection).postInitialize(collection);
        // addInitializedCollection(collection, persister, id);
        return true;
	}
}