/*******************************************************************************
 * Australian National University Data Commons
 * Copyright (C) 2013  The Australian National University
 * 
 * This file is part of Australian National University Data Commons.
 * 
 * Australian National University Data Commons is free software: you
 * can redistribute it and/or modify it under the terms of the GNU
 * General Public License as published by the Free Software Foundation,
 * either version 3 of the License, or (at your option) any later
 * version.
 * 
 * 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/

package au.edu.anu.datacommons.doi.logging;

import java.io.Closeable;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import au.edu.anu.datacommons.data.db.PersistenceManager;
import au.edu.anu.datacommons.data.db.dao.DaoException;

/**
 * DAO object for responsible for persisting {@link ExtWebResourceLog} instances.
 * 
 * @author Rahul Khanna
 *
 */
public class ExtWebResourceLogDao implements Closeable {
	private static final Logger LOGGER = LoggerFactory.getLogger(ExtWebResourceLogDao.class);

	protected EntityManager entityManager;

	public ExtWebResourceLogDao() {
		this.entityManager = PersistenceManager.getEntityManagerFactory().createEntityManager();
	}

	@Override
	public void close() {
		if (this.entityManager != null)
			this.entityManager.close();
	}

	/**
	 * Persists an instance of {@link ExtWebResourceLog}
	 * 
	 * @param log
	 *            Log instance to persist
	 * @throws DaoException
	 *             when unable to persist
	 */
	public void create(ExtWebResourceLog log) throws DaoException {
		EntityTransaction et = null;
		try {
			et = this.entityManager.getTransaction();
			et.begin();
			this.entityManager.persist(log);
			et.commit();
		} catch (Exception e) {
			try {
				if (et != null)
					et.rollback();
			} catch (Exception e1) {
				LOGGER.warn(e1.getMessage(), e1);
			}
			throw new DaoException(e);
		}
	}

	/**
	 * Updates a previously persisted instance of {@link ExtWebResourceLog}, with the response received from the
	 * external web service.
	 * 
	 * @param log
	 *            Log instance to persist
	 * @return Updated log object
	 * @throws DaoException
	 *             when unable to persist
	 */
	public ExtWebResourceLog update(ExtWebResourceLog log) throws DaoException {
		EntityTransaction et = null;
		try {
			et = this.entityManager.getTransaction();
			et.begin();
			log = this.entityManager.merge(log);
			et.commit();
		} catch (Exception e) {
			try {
				if (et != null)
					et.rollback();
			} catch (Exception e1) {
				LOGGER.warn(e1.getMessage(), e1);
			}
			throw new DaoException(e);
		}

		return log;
	}
}