Login na stara sistema

if (LOGIN){
	$error = '';
	   if (isset($_POST['login'])) {
        $username = strtolower(mysqli_real_escape_string($mysqli_server, $_POST['username']));
        $password = mysqli_real_escape_string($mysqli_server, $_POST['password']);
        function checkPassword($password, $db_password)
        {
            $parts  = explode('$', $db_password);
            $salt   = $parts[2];
            $hashed = hash('sha256', hash('sha256', $password) . $salt);
            $hashed = '$SHA$' . $salt . '$' . $hashed;
            return $hashed;
        }
        $sql    = "SELECT * FROM `authme` WHERE username='$username'";
        $result = $mysqli_server->query($sql);
        if ($result->num_rows == '1') {
            while ($row = $result->fetch_assoc()) {
                $password = checkPassword($password, $row["password"]);
                $sql      = "SELECT * FROM `authme` WHERE username='$username' AND password='$password'";
                $result   = $mysqli_server->query($sql);
                if ($result->num_rows == '1') {
                    while ($row = $result->fetch_assoc()) {
                        $error                = '<p class="highlighted"><span>Successful login.</span></p>';
                        $_SESSION['store_username'] = $username;
                        header('Location: ' . $_SERVER['REQUEST_URI']);
                    }
                } else {
                    $error = '<p class="highlighted"><span>Sorry!</span> Invalid password.</p>';
                }
            }
        } else {
            $error = '<p class="highlighted"><span>Sorry!</span> Invalid username.</p>';
        }

    }
	exit;
}