/**
 * Copyright (C) 2011  JTalks.org Team
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.jtalks.jcommune.model.dao.hibernate;

import java.util.List;

import org.hibernate.SessionFactory;
import org.hibernate.criterion.Restrictions;
import org.hibernate.criterion.SimpleExpression;
import org.jtalks.common.model.entity.Entity;
import org.jtalks.jcommune.model.dao.ValidatorDao;

/**
 * Performs simple checks in a database for the sake of validation.
 * This implementation supports only string params for simplicity
 *
 * @author Evgeniy Naumenko
 */
public class ValidatorHibernateDao implements ValidatorDao<String> {

    private SessionFactory sessionFactory;

    /**
     * @param sessionFactory to obtain current hibernate session
     */
    public ValidatorHibernateDao(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isResultSetEmpty(Class<? extends Entity> entity, String field, 
            String param, boolean ignoreCase) {
        return getResultSet(entity, field, param, ignoreCase).isEmpty();
    }
    
    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isExists(Class<? extends Entity> entity, String field, 
            String param, boolean ignoreCase) {
        List<?> resultSet = getResultSet(entity, field, param, ignoreCase);
        
        if (resultSet.isEmpty()) {
            return false;
        } else if (resultSet.size() == 1 || !ignoreCase) {
            return true;
        } else {
            return !sessionFactory
                .getCurrentSession()
                .createCriteria(entity)
                .add(Restrictions.eq(field, param))
                .setCacheable(true)
                .list()
                .isEmpty();
        }
    }
    
    private List<?> getResultSet(Class<? extends Entity> entity, String field, 
            String param, boolean ignoreCase) {
        SimpleExpression fieldRestriction = Restrictions.eq(field, param);
        if (ignoreCase) {
            fieldRestriction = fieldRestriction.ignoreCase();
        }
        return sessionFactory
            .getCurrentSession()
            .createCriteria(entity)
            .add(fieldRestriction)
            .setCacheable(true)
            .list();
    }
}