/**
 * Copyright (c) 2012, 2013, 2014, 2015, 2016 SURFnet BV
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
 * following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice, this list of conditions and the following
 *     disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
 *     disclaimer in the documentation and/or other materials provided with the distribution.
 *   * Neither the name of the SURFnet BV nor the names of its contributors may be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package nl.surfnet.bod;

import java.sql.Connection;
import java.sql.SQLException;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceException;

import org.hibernate.Session;
import org.hibernate.internal.SessionImpl;
import org.springframework.jdbc.datasource.DataSourceUtils;
import org.springframework.orm.jpa.vendor.HibernateJpaDialect;
import org.springframework.transaction.TransactionDefinition;
import org.springframework.transaction.TransactionException;

/**
 * Adapted from {@link http://shahzad-mughal.blogspot.nl/2012/04/spring-jpa-hibernate-support-for-custom.html}.
 */
@SuppressWarnings("serial")
final class HibernateJpaDialectWithTransactionIsolationSupport extends HibernateJpaDialect {

  @Override
  public Object beginTransaction(EntityManager entityManager, TransactionDefinition definition)
      throws PersistenceException, SQLException, TransactionException {

    Session session = (Session) entityManager.getDelegate();
    if (definition.getTimeout() != TransactionDefinition.TIMEOUT_DEFAULT) {
      getSession(entityManager).getTransaction().setTimeout(definition.getTimeout());
    }

    Connection connection = ((SessionImpl) session).connection();
    Integer previousIsolationLevel = DataSourceUtils.prepareConnectionForTransaction(connection, definition);

    entityManager.getTransaction().begin();

    Object transactionDataFromHibernateJpaDialect = prepareTransaction(entityManager, definition.isReadOnly(), definition.getName());
    return new IsolationSupportSessionTransactionData(transactionDataFromHibernateJpaDialect, previousIsolationLevel, connection);
  }

  @Override
  public void cleanupTransaction(Object transactionData) {
    super.cleanupTransaction(((IsolationSupportSessionTransactionData) transactionData).getSessionTransactionDataFromHibernateTemplate());
    ((IsolationSupportSessionTransactionData) transactionData).resetIsolationLevel();
  }

  private static class IsolationSupportSessionTransactionData {

    private final Object sessionTransactionDataFromHibernateJpaTemplate;
    private final Integer previousIsolationLevel;
    private final Connection connection;

    public IsolationSupportSessionTransactionData(Object sessionTransactionDataFromHibernateJpaTemplate, Integer previousIsolationLevel, Connection connection) {
      this.sessionTransactionDataFromHibernateJpaTemplate = sessionTransactionDataFromHibernateJpaTemplate;
      this.previousIsolationLevel = previousIsolationLevel;
      this.connection = connection;
    }

    public void resetIsolationLevel() {
      DataSourceUtils.resetConnectionAfterTransaction(connection, previousIsolationLevel);
    }

    public Object getSessionTransactionDataFromHibernateTemplate() {
      return this.sessionTransactionDataFromHibernateJpaTemplate;
    }

  }
}