/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2012, 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.loader.entity.plan;

import java.io.Serializable;
import java.util.List;

import org.hibernate.LockMode;
import org.hibernate.LockOptions;
import org.hibernate.engine.spi.LoadQueryInfluencers;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.internal.util.collections.ArrayHelper;
import org.hibernate.loader.entity.UniqueEntityLoader;
import org.hibernate.persister.entity.OuterJoinLoadable;

LoadPlan-based implementation of the the legacy batch loading strategy
Author:
Steve Ebersole/**
 * LoadPlan-based implementation of the the legacy batch loading strategy
 *
 * @author Steve Ebersole
 */
public class LegacyBatchingEntityLoaderBuilder extends AbstractBatchingEntityLoaderBuilder {
	public static final LegacyBatchingEntityLoaderBuilder INSTANCE = new LegacyBatchingEntityLoaderBuilder();

	@Override
	protected UniqueEntityLoader buildBatchingLoader(
			OuterJoinLoadable persister,
			int batchSize,
			LockMode lockMode,
			SessionFactoryImplementor factory,
			LoadQueryInfluencers influencers) {
		return new LegacyBatchingEntityLoader( persister, batchSize, lockMode, factory, influencers );
	}

	@Override
	protected UniqueEntityLoader buildBatchingLoader(
			OuterJoinLoadable persister,
			int batchSize,
			LockOptions lockOptions,
			SessionFactoryImplementor factory,
			LoadQueryInfluencers influencers) {
		return new LegacyBatchingEntityLoader( persister, batchSize, lockOptions, factory, influencers );
	}

	public static class LegacyBatchingEntityLoader extends BatchingEntityLoader  {
		private final int[] batchSizes;
		private final EntityLoader[] loaders;

		public LegacyBatchingEntityLoader(
				OuterJoinLoadable persister,
				int maxBatchSize,
				LockMode lockMode,
				SessionFactoryImplementor factory,
				LoadQueryInfluencers loadQueryInfluencers) {
			super( persister );
			this.batchSizes = ArrayHelper.getBatchSizes( maxBatchSize );
			this.loaders = new EntityLoader[ batchSizes.length ];
			final EntityLoader.Builder entityLoaderBuilder = EntityLoader.forEntity( persister )
					.withInfluencers( loadQueryInfluencers )
					.withLockMode( lockMode );
			for ( int i = 0; i < batchSizes.length; i++ ) {
				this.loaders[i] = entityLoaderBuilder.withBatchSize( batchSizes[i] ).byPrimaryKey();
			}
		}

		public LegacyBatchingEntityLoader(
				OuterJoinLoadable persister,
				int maxBatchSize,
				LockOptions lockOptions,
				SessionFactoryImplementor factory,
				LoadQueryInfluencers loadQueryInfluencers) {
			super( persister );
			this.batchSizes = ArrayHelper.getBatchSizes( maxBatchSize );
			this.loaders = new EntityLoader[ batchSizes.length ];
			final EntityLoader.Builder entityLoaderBuilder = EntityLoader.forEntity( persister )
					.withInfluencers( loadQueryInfluencers )
					.withLockOptions( lockOptions );
			for ( int i = 0; i < batchSizes.length; i++ ) {
				this.loaders[i] = entityLoaderBuilder.withBatchSize( batchSizes[i] ).byPrimaryKey();
			}
		}

		@Override
		public Object load(Serializable id, Object optionalObject, SessionImplementor session, LockOptions lockOptions) {
			final Serializable[] batch = session.getPersistenceContext()
					.getBatchFetchQueue()
					.getEntityBatch( persister(), id, batchSizes[0], persister().getEntityMode() );

			for ( int i = 0; i < batchSizes.length-1; i++) {
				final int smallBatchSize = batchSizes[i];
				if ( batch[smallBatchSize-1] != null ) {
					Serializable[] smallBatch = new Serializable[smallBatchSize];
					System.arraycopy(batch, 0, smallBatch, 0, smallBatchSize);
					// for now...
					final List results = loaders[i].loadEntityBatch(
							session,
							smallBatch,
							persister().getIdentifierType(),
							optionalObject,
							persister().getEntityName(),
							id,
							persister(),
							lockOptions
					);
					//EARLY EXIT
					return getObjectFromList( results, id, session );
				}
			}
			return ( loaders[batchSizes.length-1] ).load( id, optionalObject, session, lockOptions );
		}
	}

}