/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2008, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This 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 software 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 software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.ejb.plugins.cmp.jdbc.keygen;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.ejb.CreateException;
import javax.sql.DataSource;

import org.jboss.deployment.DeploymentException;
import org.jboss.ejb.EntityEnterpriseContext;
import org.jboss.ejb.plugins.cmp.jdbc.bridge.JDBCCMPFieldBridge;
import org.jboss.ejb.plugins.cmp.jdbc.metadata.JDBCEntityCommandMetaData;
import org.jboss.ejb.plugins.cmp.jdbc.JDBCInsertPKCreateCommand;
import org.jboss.ejb.plugins.cmp.jdbc.JDBCStoreManager;
import org.jboss.ejb.plugins.cmp.jdbc.JDBCUtil;

/**
 * Create command that uses an SQL statement to generate the primary key.
 * Typically used with databases that support sequences.
 *
 * @author <a href="mailto:loubyansky@hotmail.com">Alex Loubyansky</a>
 *
 * @version $Revision: 81030 $
 */
public class JDBCPkSqlCreateCommand extends JDBCInsertPKCreateCommand
{
   protected String pkSQL;
   protected JDBCCMPFieldBridge pkField;

   public void init(JDBCStoreManager manager) throws DeploymentException
   {
      super.init(manager);
      pkField = getGeneratedPKField();
   }

   protected void initEntityCommand(JDBCEntityCommandMetaData entityCommand) throws DeploymentException
   {
      super.initEntityCommand(entityCommand);

      pkSQL = entityCommand.getAttribute("pk-sql");
      if(pkSQL == null)
      {
         throw new DeploymentException("pk-sql attribute must be set for entity " + entity.getEntityName());
      }
      if(debug)
      {
         log.debug("Generate PK sql is: " + pkSQL);
      }
   }

   protected void generateFields(EntityEnterpriseContext ctx) throws CreateException
   {
      super.generateFields(ctx);

      Connection con = null;
      Statement s = null;
      ResultSet rs = null;
      try
      {
         if(debug)
         {
            log.debug("Executing SQL: " + pkSQL);
         }

         DataSource dataSource = entity.getDataSource();
         con = dataSource.getConnection();
         s = con.createStatement();

         rs = s.executeQuery(pkSQL);
         if(!rs.next())
         {
            throw new CreateException("Error fetching next primary key value: result set contains no rows");
         }
         pkField.loadInstanceResults(rs, 1, ctx);
      }
      catch(SQLException e)
      {
         log.error("Error fetching the next primary key value", e);
         throw new CreateException("Error fetching the next primary key value:" + e);
      }
      finally
      {
         JDBCUtil.safeClose(rs);
         JDBCUtil.safeClose(s);
         JDBCUtil.safeClose(con);
      }
   }
}