/* 
 * Hibernate, Relational Persistence for Idiomatic Java
 * 
 * JBoss, Home of Professional Open Source
 * Copyright 2012 Red Hat Inc. and/or its affiliates and other contributors
 * as indicated by the @authors tag. All rights reserved.
 * See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * 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, v. 2.1.
 * This program is distributed in the hope that it will be useful, but WITHOUT A
 * 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,
 * v.2.1 along with this distribution; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA  02110-1301, USA.
 */
package org.hibernate.search.batchindexing.impl;

import javax.transaction.Status;
import javax.transaction.SystemException;
import javax.transaction.TransactionManager;

import org.hibernate.search.exception.ErrorHandler;
import org.hibernate.search.util.logging.impl.Log;

import org.hibernate.SessionFactory;
import org.hibernate.StatelessSession;
import org.hibernate.Session;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.search.util.logging.impl.LoggerFactory;
import org.hibernate.engine.transaction.spi.TransactionFactory;
import org.hibernate.service.jta.platform.spi.JtaPlatform;

/**
 * Wrap the subsequent Runnable in a JTA Transaction if necessary:
 *  - if the existing Hibernate Core transaction strategy requires a TransactionManager
 *  - if no JTA transaction is already started
 *
 * Unfortunately at this time we need to have access to SessionFactoryImplementor
 *
 * @author Emmanuel Bernard
 */
public class OptionallyWrapInJTATransaction implements Runnable {

	private static final Log log = LoggerFactory.make();

	private final SessionFactoryImplementor factory;
	private final SessionAwareRunnable sessionAwareRunnable;
	private final StatelessSessionAwareRunnable statelessSessionAwareRunnable;
	private final ErrorHandler errorHandler;

	public OptionallyWrapInJTATransaction(SessionFactory factory, ErrorHandler errorHandler, SessionAwareRunnable sessionAwareRunnable) {
		/*
		 * Unfortunately we need to access SessionFactoryImplementor to detect:
		 *  - whether or not we need to start the JTA transaction
		 *  - start it
		 */
		//TODO get SessionFactoryImplementor it from the SearchFactory as we might get a hold of the SFI at startup time
		// if that's the case, SearchFactory should expose something like T unwrap(Class<T> clazz);
		this.factory = (SessionFactoryImplementor) factory;
		this.sessionAwareRunnable = sessionAwareRunnable;
		this.statelessSessionAwareRunnable = null;
		this.errorHandler = errorHandler;
	}

	public OptionallyWrapInJTATransaction(SessionFactory factory, ErrorHandler errorHandler, StatelessSessionAwareRunnable statelessSessionAwareRunnable) {
		/*
		 * Unfortunately we need to access SessionFactoryImplementor to detect:
		 *  - whether or not we need to start the JTA transaction
		 *  - start it
		 */
		//TODO get SessionFactoryImplementor it from the SearchFactory as we might get a hold of the SFI at startup time
		// if that's the case, SearchFactory should expose something like T unwrap(Class<T> clazz);
		this.factory = (SessionFactoryImplementor) factory;
		this.sessionAwareRunnable = null;
		this.statelessSessionAwareRunnable = statelessSessionAwareRunnable;
		this.errorHandler = errorHandler;
	}

	public void run() {
		try {
			final boolean wrapInTransaction = wrapInTransaction();
			if ( wrapInTransaction ) {
				TransactionManager transactionManager = getTransactionManager();
				try {
					final Session session;
					final StatelessSession statelessSession;
					if ( sessionAwareRunnable != null ) {
						session = factory.openSession();
						statelessSession = null;
					}
					else {
						session = null;
						statelessSession = factory.openStatelessSession();
					}
	
					transactionManager.begin();
	
					if ( sessionAwareRunnable != null ) {
						sessionAwareRunnable.run( session );
					}
					else {
						statelessSessionAwareRunnable.run( statelessSession );
					}
	
					transactionManager.commit();
	
					if ( sessionAwareRunnable != null ) {
						session.close();
					}
					else {
						statelessSession.close();
					}
				}
				catch (Throwable e) {
					errorHandler.handleException( log.massIndexerUnexpectedErrorMessage() , e);
					try {
						transactionManager.rollback();
					}
					catch ( SystemException e1 ) {
						// we already have an exception, don't propagate this one
						log.errorRollingBackTransaction( e.getMessage(), e1 );
					}
				}
			}
			else {
				if ( sessionAwareRunnable != null ) {
					sessionAwareRunnable.run( null );
				}
				else {
					statelessSessionAwareRunnable.run( null );
				}
			}
		}
		catch (Throwable e) {
			errorHandler.handleException( log.massIndexerUnexpectedErrorMessage() , e);
		}
	}

	private TransactionManager getTransactionManager() {
		return factory.getServiceRegistry().getService(JtaPlatform.class).retrieveTransactionManager();
	}

	boolean wrapInTransaction() {
		final TransactionFactory transactionFactory = factory.getServiceRegistry().getService(TransactionFactory.class);
		if ( !transactionFactory.compatibleWithJtaSynchronization() ) {
			//Today we only require a TransactionManager on JTA based transaction factories
			log.trace( "TransactionFactory does not require a TransactionManager: don't wrap in a JTA transaction" );
			return false;
		}
		final TransactionManager transactionManager = getTransactionManager();
		if ( transactionManager == null ) {
			//no TM, nothing to do OR configuration mistake
			log.trace( "No TransactionManager found, do not start a surrounding JTA transaction" );
			return false;
		}
		try {
			if ( transactionManager.getStatus() == Status.STATUS_NO_TRANSACTION ) {
				log.trace( "No Transaction in progress, needs to start a JTA transaction" );
				return true;
			}
		}
		catch ( SystemException e ) {
			log.cannotGuessTransactionStatus( e );
			return false;
		}
		log.trace( "Transaction in progress, no needs to start a JTA transaction" );
		return false;
	}
}