/*
 * 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;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.SQLException;
import javax.sql.DataSource;
import javax.transaction.Transaction;
import javax.transaction.TransactionManager;

import org.jboss.ejb.plugins.cmp.jdbc.bridge.JDBCAbstractCMRFieldBridge;
import org.jboss.ejb.plugins.cmp.jdbc.bridge.JDBCAbstractEntityBridge;
import org.jboss.ejb.plugins.cmp.jdbc.metadata.JDBCEntityMetaData;
import org.jboss.ejb.plugins.cmp.jdbc.metadata.JDBCRelationMetaData;
import org.jboss.logging.Logger;


/**
 * JDBCStopCommand drops the table for this entity if specified in the xml.
 *
 * @author <a href="mailto:dain@daingroup.com">Dain Sundstrom</a>
 * @author <a href="mailto:rickard.oberg@telkel.com">Rickard Oberg</a>
 * @author <a href="mailto:justin@j-m-f.demon.co.uk">Justin Forder</a>
 * @author <a href="mailto:alex@jboss.org">Alexey Loubyansky</a>
 * @version $Revision: 81030 $
 */
public final class JDBCStopCommand
{
   private final JDBCEntityPersistenceStore manager;
   private final JDBCAbstractEntityBridge entity;
   private final JDBCEntityMetaData entityMetaData;
   private final Logger log;

   public JDBCStopCommand(JDBCEntityPersistenceStore manager)
   {
      this.manager = manager;
      entity = manager.getEntityBridge();
      entityMetaData = entity.getMetaData();

      // Create the Log
      log = Logger.getLogger(
         this.getClass().getName() +
         "." +
         manager.getMetaData().getName());
   }

   public boolean execute()
   {
      boolean success = true;

      // drop relation tables
      JDBCAbstractCMRFieldBridge[] cmrFields = entity.getCMRFields();
      for(int i = 0; i < cmrFields.length; ++i)
      {
         JDBCAbstractCMRFieldBridge cmrField = cmrFields[i];
         JDBCRelationMetaData relationMetaData = cmrField.getMetaData().getRelationMetaData();
         if(relationMetaData.isTableMappingStyle() && !relationMetaData.isTableDropped())
         {
            if(relationMetaData.getRemoveTable())
            {
               final boolean dropped = dropTable(relationMetaData.getDataSource(), cmrField.getQualifiedTableName());
               if(!dropped)
               {
                  success = false;
               }
               else
               {
                  relationMetaData.setTableDropped();
               }
            }
         }
      }

      if(entityMetaData.getRemoveTable())
      {
         boolean dropped = dropTable(entity.getDataSource(), entity.getQualifiedTableName());
         if(!dropped)
         {
            success = false;
         }
      }

      return success;
   }

   private boolean dropTable(DataSource dataSource, String qualifiedTableName)
   {
      boolean success;
      Connection con = null;
      ResultSet rs = null;

      String schema = SQLUtil.getSchema(qualifiedTableName);
      String tableName = schema != null ? SQLUtil.getTableNameWithoutSchema(qualifiedTableName) : qualifiedTableName;

      // was the table already delete?
      try
      {
         con = dataSource.getConnection();
         DatabaseMetaData dmd = con.getMetaData();
         rs = dmd.getTables(con.getCatalog(), schema, tableName, null);
         if(!rs.next())
         {
            return true;
         }
      }
      catch(SQLException e)
      {
         log.debug("Error getting database metadata for DROP TABLE command. " +
            " DROP TABLE will not be executed. ", e);
         return true;
      }
      finally
      {
         JDBCUtil.safeClose(rs);
         JDBCUtil.safeClose(con);
      }

      // since we use the pools, we have to do this within a transaction

      // suspend the current transaction
      TransactionManager tm = manager.getContainer().getTransactionManager();
      Transaction oldTransaction = null;
      try
      {
         oldTransaction = tm.suspend();
      }
      catch(Exception e)
      {
         log.error("Could not suspend current transaction before drop table. " +
            "'" + qualifiedTableName + "' will not be dropped.", e);
      }

      try
      {
         Statement statement = null;
         try
         {
            con = dataSource.getConnection();
            statement = con.createStatement();

            // execute sql
            String sql = SQLUtil.DROP_TABLE + qualifiedTableName;
            log.debug("Executing SQL: " + sql);
            statement.executeUpdate(sql);
            success = true;
         }
         finally
         {
            JDBCUtil.safeClose(statement);
            JDBCUtil.safeClose(con);
         }
      }
      catch(Exception e)
      {
         log.debug("Could not drop table " + qualifiedTableName + ": " + e.getMessage());
         success = false;
      }
      finally
      {
         try
         {
            // resume the old transaction
            if(oldTransaction != null)
            {
               tm.resume(oldTransaction);
            }
         }
         catch(Exception e)
         {
            log.error("Could not reattach original transaction after drop table");
         }
      }

      return success;
   }
}