/*
      Copyright (C) 2002-2004 MySQL AB

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

      There are special exceptions to the terms and conditions of the GPL 
      as it is applied to this software. View the full text of the 
      exception in file EXCEPTIONS-CONNECTOR-J in the directory of this 
      software distribution.

      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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



 */
package com.mysql.jdbc;

import java.rmi.server.UID;
import java.sql.SQLException;
import java.sql.Savepoint;

/**
 * Represents SQL SAVEPOINTS in MySQL.
 * 
 * @author Mark Matthews
 *
 * @version $Id: MysqlSavepoint.java,v 1.1.2.4 2004/08/12 20:28:29 mmatthew Exp $
 */
public class MysqlSavepoint implements Savepoint {
	private String savepointName;
	
	/**
	 * Creates an unnamed savepoint.
	 * @param conn
	 * 
	 * @throws SQLException if an error occurs
	 */
	MysqlSavepoint() throws SQLException {
		this(getUniqueId());
	}
	
	/**
	 * Creates a named savepoint
	 * @param name the name of the savepoint.
	 * 
	 * @throws SQLException if name == null or is empty.
	 */
	MysqlSavepoint(String name) throws SQLException {
		if (name == null || name.length() == 0) {
			throw new SQLException("Savepoint name can not be NULL or empty", SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
		}
		
		this.savepointName = name;
	}
	
	/**
	 * @see java.sql.Savepoint#getSavepointId()
	 */
	public int getSavepointId() throws SQLException {
		throw new SQLException("Only named savepoints are supported.", SQLError.SQL_STATE_DRIVER_NOT_CAPABLE);
	}

	/**
	 * @see java.sql.Savepoint#getSavepointName()
	 */
	public String getSavepointName() throws SQLException {
		return this.savepointName;
	}

	private static String getUniqueId() {
		// no need to re-invent the wheel here...
		String uidStr = new UID().toString();
		
		int uidLength = uidStr.length();
		
		StringBuffer safeString = new StringBuffer(uidLength);
		
		for (int i = 0; i < uidLength; i++) {
			char c = uidStr.charAt(i);
			
			if (Character.isLetter(c) || Character.isDigit(c)) {
				safeString.append(c);
			} else {
				safeString.append('_');
			}
		}
		
		return safeString.toString();
	}
}