/*
  Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.

  The MySQL Connector/J is licensed under the terms of the GPLv2
  <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most MySQL Connectors.
  There are special exceptions to the terms and conditions of the GPLv2 as it is applied to
  this software, see the FLOSS License Exception
  <http://www.mysql.com/about/legal/licensing/foss-exception.html>.

  This program is free software; you can redistribute it and/or modify it under the terms
  of the GNU General Public License as published by the Free Software Foundation; version 2
  of the License.

  This program 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 General Public License for more details.

  You should have received a copy of the GNU General Public License along with this
  program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
  Floor, Boston, MA 02110-1301  USA
 
 */

package com.mysql.jdbc.interceptors;

import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.ResultSetInternalMethods;
import com.mysql.jdbc.Statement;
import com.mysql.jdbc.StatementInterceptor;
import com.mysql.jdbc.Util;

public class ServerStatusDiffInterceptor implements StatementInterceptor {

	private Map<String, String> preExecuteValues = new HashMap<String, String>();

	private Map<String, String> postExecuteValues = new HashMap<String, String>();

	public void init(Connection conn, Properties props) throws SQLException {

	}

	public ResultSetInternalMethods postProcess(String sql,
			Statement interceptedStatement,
			ResultSetInternalMethods originalResultSet, Connection connection)
			throws SQLException {

		if (connection.versionMeetsMinimum(5, 0, 2)) {
			populateMapWithSessionStatusValues(connection, this.postExecuteValues);
	
			connection.getLog().logInfo(
					"Server status change for statement:\n"
							+ Util.calculateDifferences(this.preExecuteValues,
									this.postExecuteValues));
		}

		return null; // we don't actually modify a result set

	}

	private void populateMapWithSessionStatusValues(Connection connection,
			Map<String, String> toPopulate) throws SQLException {
		java.sql.Statement stmt = null;
		java.sql.ResultSet rs = null;

		try {
			toPopulate.clear();

			stmt = connection.createStatement();
			rs = stmt.executeQuery("SHOW SESSION STATUS");
			Util.resultSetToMap(toPopulate, rs);
		} finally {
			if (rs != null) {
				rs.close();
			}

			if (stmt != null) {
				stmt.close();
			}
		}
	}

	public ResultSetInternalMethods preProcess(String sql,
			Statement interceptedStatement, Connection connection)
			throws SQLException {

		if (connection.versionMeetsMinimum(5, 0, 2)) {
			populateMapWithSessionStatusValues(connection,
					this.preExecuteValues);
		}

		return null; // we don't actually modify a result set
	}

	public boolean executeTopLevelOnly() {
		return true;
	}

	public void destroy() {
		
	}
}
