/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2007-2011, 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.engine.transaction.internal.jdbc;

import java.sql.Connection;
import java.sql.SQLException;
import org.hibernate.HibernateException;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.TransactionException;
import org.hibernate.engine.transaction.spi.AbstractTransactionImpl;
import org.hibernate.engine.transaction.spi.IsolationDelegate;
import org.hibernate.engine.transaction.spi.JoinStatus;
import org.hibernate.engine.transaction.spi.LocalStatus;
import org.hibernate.engine.transaction.spi.TransactionCoordinator;

import org.jboss.logging.Logger;

/**
 * {@link org.hibernate.Transaction} implementation based on transaction management through a JDBC {@link java.sql.Connection}.
 * <p/>
 * This the default transaction strategy.
 *
 * @author Anton van Straaten
 * @author Gavin King
 * @author Steve Ebersole
 */
public class JdbcTransaction extends AbstractTransactionImpl {

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

	private Connection managedConnection;
	private boolean wasInitiallyAutoCommit;
	private boolean isDriver;

	protected JdbcTransaction(TransactionCoordinator transactionCoordinator) {
		super( transactionCoordinator );
	}

	@Override
	protected void doBegin() {
		try {
			if ( managedConnection != null ) {
				throw new TransactionException( "Already have an associated managed connection" );
			}
			managedConnection = transactionCoordinator().getJdbcCoordinator().getLogicalConnection().getConnection();
			wasInitiallyAutoCommit = managedConnection.getAutoCommit();
            LOG.debug("initial autocommit status: " + wasInitiallyAutoCommit);
			if ( wasInitiallyAutoCommit ) {
                LOG.debug("disabling autocommit");
				managedConnection.setAutoCommit( false );
			}
		}
		catch( SQLException e ) {
			throw new TransactionException( "JDBC begin transaction failed: ", e );
		}

		isDriver = transactionCoordinator().takeOwnership();
	}

	@Override
	protected void afterTransactionBegin() {
		if ( getTimeout() > 0 ) {
			transactionCoordinator().getJdbcCoordinator().setTransactionTimeOut( getTimeout() );
		}
		transactionCoordinator().sendAfterTransactionBeginNotifications( this );
		if ( isDriver ) {
			transactionCoordinator().getTransactionContext().afterTransactionBegin( this );
		}
	}

	@Override
	protected void beforeTransactionCommit() {
		transactionCoordinator().sendBeforeTransactionCompletionNotifications( this );

		// basically, if we are the driver of the transaction perform a managed flush prior to
		// physically committing the transaction
		if ( isDriver && !transactionCoordinator().getTransactionContext().isFlushModeNever() ) {
			// if an exception occurs during flush, user must call rollback()
			transactionCoordinator().getTransactionContext().managedFlush();
		}

		if ( isDriver ) {
			transactionCoordinator().getTransactionContext().beforeTransactionCompletion( this );
		}
	}

	@Override
	protected void doCommit() throws TransactionException {
		try {
			managedConnection.commit();
            LOG.debug("committed JDBC Connection");
		}
		catch( SQLException e ) {
			throw new TransactionException( "unable to commit against JDBC connection", e );
		}
		finally {
			releaseManagedConnection();
		}
	}

	private void releaseManagedConnection() {
		try {
			if ( wasInitiallyAutoCommit ) {
                LOG.debug("re-enabling autocommit");
				managedConnection.setAutoCommit( true );
			}
			managedConnection = null;
		}
		catch ( Exception e ) {
            LOG.debug("Could not toggle autocommit", e);
		}
	}

	@Override
	protected void afterTransactionCompletion(int status) {
		transactionCoordinator().afterTransaction( this, status );
	}

	@Override
	protected void afterAfterCompletion() {
		if ( isDriver
				&& transactionCoordinator().getTransactionContext().shouldAutoClose()
				&& !transactionCoordinator().getTransactionContext().isClosed() ) {
			try {
				transactionCoordinator().getTransactionContext().managedClose();
			}
			catch (HibernateException e) {
                LOG.unableToCloseSessionButSwallowingError(e);
			}
		}
	}

	@Override
	protected void beforeTransactionRollBack() {
		// nothing to do here
	}

	@Override
	protected void doRollback() throws TransactionException {
		try {
			managedConnection.rollback();
            LOG.debug("rolled JDBC Connection");
		}
		catch( SQLException e ) {
			throw new TransactionException( "unable to rollback against JDBC connection", e );
		}
		finally {
			releaseManagedConnection();
		}
	}

	@Override
	public boolean isInitiator() {
		return isActive();
	}

	@Override
	public IsolationDelegate createIsolationDelegate() {
		return new JdbcIsolationDelegate( transactionCoordinator() );
	}

	@Override
	public JoinStatus getJoinStatus() {
		return isActive() ? JoinStatus.JOINED : JoinStatus.NOT_JOINED;
	}

	@Override
	public void markRollbackOnly() {
		// nothing to do here
	}

	@Override
	public void join() {
		// nothing to do
	}

	@Override
	public void resetJoinStatus() {
		// nothing to do
	}

	@Override
	public boolean isActive() throws HibernateException {
		return getLocalStatus() == LocalStatus.ACTIVE;
	}
}