/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.orm.jpa.vendor;

import java.util.HashMap;
import java.util.Map;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.spi.PersistenceProvider;

import org.hibernate.cfg.Environment;
import org.hibernate.dialect.DB2Dialect;
import org.hibernate.dialect.DerbyDialect;
import org.hibernate.dialect.H2Dialect;
import org.hibernate.dialect.HSQLDialect;
import org.hibernate.dialect.InformixDialect;
import org.hibernate.dialect.MySQLDialect;
import org.hibernate.dialect.Oracle9iDialect;
import org.hibernate.dialect.PostgreSQLDialect;
import org.hibernate.dialect.SQLServerDialect;
import org.hibernate.dialect.SybaseDialect;
import org.hibernate.ejb.HibernateEntityManager;
import org.hibernate.ejb.HibernateEntityManagerFactory;
import org.hibernate.ejb.HibernatePersistence;

import org.springframework.orm.jpa.JpaDialect;

/**
 * {@link org.springframework.orm.jpa.JpaVendorAdapter} implementation for
 * Hibernate EntityManager. Developed and tested against Hibernate 3.3.
 *
 * <p>Exposes Hibernate's persistence provider and EntityManager extension interface,
 * and supports {@link AbstractJpaVendorAdapter}'s common configuration settings.
 *
 * @author Juergen Hoeller
 * @author Rod Johnson
 * @since 2.0
 * @see org.hibernate.ejb.HibernatePersistence
 * @see org.hibernate.ejb.HibernateEntityManager
 */
public class HibernateJpaVendorAdapter extends AbstractJpaVendorAdapter {

	private final PersistenceProvider persistenceProvider = new HibernatePersistence();

	private final JpaDialect jpaDialect = new HibernateJpaDialect();


	public PersistenceProvider getPersistenceProvider() {
		return this.persistenceProvider;
	}

	@Override
	public String getPersistenceProviderRootPackage() {
		return "org.hibernate";
	}

	@Override
	public Map<String, Object> getJpaPropertyMap() {
		Map<String, Object> jpaProperties = new HashMap<String, Object>();

		if (getDatabasePlatform() != null) {
			jpaProperties.put(Environment.DIALECT, getDatabasePlatform());
		}
		else if (getDatabase() != null) {
			Class databaseDialectClass = determineDatabaseDialectClass(getDatabase());
			if (databaseDialectClass != null) {
				jpaProperties.put(Environment.DIALECT, databaseDialectClass.getName());
			}
		}

		if (isGenerateDdl()) {
			jpaProperties.put(Environment.HBM2DDL_AUTO, "update");
		}
		if (isShowSql()) {
			jpaProperties.put(Environment.SHOW_SQL, "true");
		}

		return jpaProperties;
	}

	/**
	 * Determine the Hibernate database dialect class for the given target database.
	 * @param database the target database
	 * @return the Hibernate database dialect class, or {@code null} if none found
	 */
	protected Class determineDatabaseDialectClass(Database database) {
		switch (database) {
			case DB2: return DB2Dialect.class;
			case DERBY: return DerbyDialect.class;
			case H2: return H2Dialect.class;
			case HSQL: return HSQLDialect.class;
			case INFORMIX: return InformixDialect.class;
			case MYSQL: return MySQLDialect.class;
			case ORACLE: return Oracle9iDialect.class;
			case POSTGRESQL: return PostgreSQLDialect.class;
			case SQL_SERVER: return SQLServerDialect.class;
			case SYBASE: return SybaseDialect.class;
			default: return null;
		}
	}

	@Override
	public JpaDialect getJpaDialect() {
		return this.jpaDialect;
	}

	@Override
	public Class<? extends EntityManagerFactory> getEntityManagerFactoryInterface() {
		return HibernateEntityManagerFactory.class;
	}

	@Override
	public Class<? extends EntityManager> getEntityManagerInterface() {
		return HibernateEntityManager.class;
	}

}
