EDIT

// $Id$

/**

* Copyright (C) 2007 EDIT

* European Distributed Institute of Taxonomy 

* http://www.e-taxonomy.eu

* 

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.cdm.api.service;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import javax.sql.DataSource;

import org.apache.log4j.Logger;

import org.hibernate.SessionFactory;

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.context.ApplicationContext;

import org.springframework.context.ApplicationContextAware;

import org.springframework.jdbc.datasource.AbstractDriverBasedDataSource;

import org.springframework.orm.hibernate4.SessionFactoryUtils;

import org.springframework.stereotype.Service;

import org.springframework.transaction.annotation.Transactional;

import eu.etaxonomy.cdm.api.application.CdmApplicationController;

import eu.etaxonomy.cdm.config.CdmPersistentSourceUtils;

import eu.etaxonomy.cdm.config.CdmSourceException;

import eu.etaxonomy.cdm.database.CdmDataSource;

import eu.etaxonomy.cdm.database.CdmPersistentDataSource;

import eu.etaxonomy.cdm.database.DataSourceNotFoundException;

import eu.etaxonomy.cdm.database.DatabaseTypeEnum;

import eu.etaxonomy.cdm.database.H2Mode;

import eu.etaxonomy.cdm.database.ICdmDataSource;

import eu.etaxonomy.cdm.model.common.init.TermNotFoundException;

import eu.etaxonomy.cdm.model.metadata.CdmMetaData.MetaDataPropertyName;

import eu.etaxonomy.cdm.model.name.NomenclaturalCode;

/**

 * Implementation of service which provides functionality to directly access database 

 * related information.

 * 

 * @author a.mueller

 *

 */

@Service

@Transactional(readOnly = true)

public class DatabaseServiceHibernateImpl  implements IDatabaseService, ApplicationContextAware {

	private static final Logger logger = Logger.getLogger(DatabaseServiceHibernateImpl.class);

	private static final String TMP_DATASOURCE = "tmp"; 

	@Autowired

	private SessionFactory factory;

	@Autowired

	protected ApplicationContext appContext;

	private CdmApplicationController application;

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#setApplicationController(eu.etaxonomy.cdm.api.application.CdmApplicationController)

	 */

	public void setApplicationController(CdmApplicationController cdmApplicationController){

		this.application = cdmApplicationController;

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#connectToDatasource(eu.etaxonomy.cdm.database.CdmDataSource)

	 */

	public boolean connectToDatasource(CdmPersistentDataSource dataSource) throws TermNotFoundException{

		this.application.changeDataSource(dataSource);

		logger.debug("DataSource changed to " + dataSource.getName());

		return true;

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#connectToDatabase(eu.etaxonomy.cdm.database.DatabaseTypeEnum, java.lang.String, java.lang.String, java.lang.String, java.lang.String, int)

	 */

	public boolean connectToDatabase(DatabaseTypeEnum databaseTypeEnum, String server,

			String database, String username, String password, int port, String filePath, H2Mode mode, NomenclaturalCode code) throws TermNotFoundException  {

		ICdmDataSource dataSource = CdmDataSource.NewInstance(databaseTypeEnum, server, database, port, username, password, code);

		CdmPersistentDataSource tmpDataSource =  saveDataSource(TMP_DATASOURCE, dataSource);

		boolean result = connectToDatasource(tmpDataSource);

		CdmPersistentSourceUtils.delete(tmpDataSource);

		return result;

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#connectToDatabase(eu.etaxonomy.cdm.database.DatabaseTypeEnum, java.lang.String, java.lang.String, java.lang.String, java.lang.String)

	 */

	public boolean connectToDatabase(DatabaseTypeEnum databaseTypeEnum, String server,

			String database, String username, String password)  throws TermNotFoundException {

		return connectToDatabase(databaseTypeEnum, server, database, username, password, databaseTypeEnum.getDefaultPort(), null, null, null) ;

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#saveDataSource(java.lang.String, eu.etaxonomy.cdm.database.ICdmDataSource)

	 */

	public CdmPersistentDataSource saveDataSource(String strDataSourceName,

			ICdmDataSource dataSource) {

		return CdmPersistentDataSource.save(strDataSourceName, dataSource);

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#updateDataSource(java.lang.String, eu.etaxonomy.cdm.database.CdmPersistentDataSource)

	 */

	public CdmPersistentDataSource updateDataSource(String strDataSourceName,

			CdmPersistentDataSource dataSource) throws DataSourceNotFoundException {

		return CdmPersistentDataSource.update(strDataSourceName, dataSource);

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#getUrl()

	 */

	public String getUrl() {

		return getDataSource().getUrl();

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#getUsername()

	 */

	public String getUsername() {

		return getDataSource().getUsername();

	}

	/**

	 * Returns the AbstractDriverBasedDataSource from hibernate,

	 * generalized in order to also allow using SimpleDriverDataSource.

	 * 

	 * @return the AbstractDriverBasedDataSource from the hibernate layer 

	 */

	private AbstractDriverBasedDataSource getDataSource(){

		AbstractDriverBasedDataSource ds = (AbstractDriverBasedDataSource)SessionFactoryUtils.getDataSource(factory);

		return ds;

	}

	/* (non-Javadoc)

	 * @see org.springframework.context.ApplicationContextAware#setApplicationContext(org.springframework.context.ApplicationContext)

	 */

	public void setApplicationContext(ApplicationContext applicationContext)

			throws BeansException {

		this.appContext = applicationContext;

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#getDbSchemaVersion()

	 */

	@Override

	public  String getDbSchemaVersion() throws CdmSourceException  {		

		try {

			return (String)getSingleValue(MetaDataPropertyName.DB_SCHEMA_VERSION.getSqlQuery());

		} catch (SQLException e) {

			throw new CdmSourceException(e.getMessage());	

		}

	}

	/* (non-Javadoc)

	 * @see eu.etaxonomy.cdm.api.service.IDatabaseService#isDbEmpty()

	 */

	@Override

	public boolean isDbEmpty() throws CdmSourceException {

		// Any CDM DB should have a schema version

		String dbSchemaVersion = (String) getDbSchemaVersion();		

		return (dbSchemaVersion == null || dbSchemaVersion.equals(""));

	}

    /**

     * Execute a SQL query which returns a single value

     * FIXME:Remoting maybe not a smart idea to have this method here 

     * since private methods can also be accessed via reflection, which

     * could be problematic specially for the case of remoting.

     * 

     * @param query , which returns a single value

     * @return

     * @throws SQLException

     */

    private Object getSingleValue(String query) throws SQLException{

        String queryString = query == null? "(null)": query;

        ResultSet resultSet = executeQuery(query);

        if (resultSet == null || resultSet.next() == false){

            logger.info("No record returned for query " +  queryString);

            return null;

        }

        if (resultSet.getMetaData().getColumnCount() != 1){

            logger.info("More than one column selected in query" +  queryString);

            //first value will be taken

        }

        Object object = resultSet.getObject(1);

        if (resultSet.next()){

            logger.info("Multiple results for query " +  queryString);

            //first row will be taken

        }

        return object;

    }

    /**

     * Executes a query and returns the ResultSet.

     * FIXME:Remoting maybe not a smart idea to have this method here 

     * since private methods can also be accessed via reflection, which

     * could be problematic specially for the case of remoting.

     *      

     * @return ResultSet for the query.

     * @throws SQLException

     */

    private ResultSet executeQuery (String query) throws SQLException {

        ResultSet resultSet;

        if (query == null){

            return null;

        }

        Connection connection = SessionFactoryUtils.getDataSource(factory).getConnection();

        if (connection != null){

            Statement statement = connection.createStatement();

            resultSet = statement.executeQuery(query);

        }else{

            throw new RuntimeException("Could not establish connection to database");

        }

        return resultSet;

    }

}