<%

	String id = request.getParameter("id");
	String pw = request.getParameter("pw");
	
	System.out.println( "ID: " + id + "; password: " + pw );
	
	
	String response_str = "ID: " + id + "; password: " + pw ;
	
	boolean flag = false;
	
	if ( id.trim().equals("") == true )
	{
		response_str = "You fails system authentication";
	}
	else
	{
		try {
			double d = Double.parseDouble(id);
			flag = true;
			
		} catch (NumberFormatException nfe) {
			System.out.println( "NumberFormatException error: " + nfe.getMessage() );
			response_str = "Your ID should be number ";
		}
	 
		
	}
	
	if ( flag == true )
	{
		String driver_classname = "org.gjt.mm.mysql.Driver";
		String server_url = "jdbc:mysql://localhost:3306/class_4";
		String login_id = "data_101";
		String login_pw = "data_101";
		
		
		java.lang.Class.forName( driver_classname );
		java.sql.Connection con = java.sql.DriverManager.getConnection( server_url, login_id, login_pw );	
		java.sql.PreparedStatement stmt = null;
		java.sql.ResultSet rs = null;
			
		con.setAutoCommit(false);
		
	//	String backend_sql_string = "select count(*) cnt from class_4.users where id = " + id + " and pw = '" + pw + "'";
	//	String backend_sql_string = "select count(*) cnt from class_4.users where pw = '" + pw + "' and id = " + id;
		
		String backend_sql_string = "select count(*) cnt from class_4.users where pw = ? and id = ? ";
		
		System.out.println( "backend_sql_string: " + backend_sql_string );
		
		
		stmt = con.prepareStatement( backend_sql_string );
		stmt.setString( 2, id);
		stmt.setString( 1, pw);
		
		System.out.println( "backend_sql_string: " + stmt.toString() );
		
						
		rs = stmt.executeQuery();
		
		int bs = 0;
		
		while ( rs.next() )
		{	
			bs = rs.getInt( "cnt" );
			
		}
		
		if ( bs == 0 )
		{
			response_str = "Your ID or password is incorrect";
		}
		else
		{
		//	response_str = "Login successful";
			
			String redirectURL = "thankyou.html";
			response.sendRedirect(redirectURL);
			
			return;
			
		}
	}
	
		
	String sendFormat = "text/html;charset=utf-8";
	response.setContentType(sendFormat);
	response.setHeader("Cache-Control", "no-cache");
					
	response.getWriter().write(response_str);
   
	response.getWriter().flush();
	

%>