function insertUserToken($token)
{
    global $GMAIL;
    $userid = getMoodleIdFromSession($_COOKIE['MoodleSession']);
    mysql_connect($GMAIL->dbhost, $GMAIL->dbuser, $GMAIL->dbpassword);
    mysql_select_db($GMAIL->dbname);
    $token = addSlashes($token);
    $query = 'insert into credentials values("","' . $userid . '","' . $token . '");';
    $result = mysql_query($query);
    $row = mysql_fetch_row($result);
    mysql_close();
    header('Location: ' . $GMAIL->successRedirect);
}
<?php

require 'gmail/autoload.php';
include "../config.php";
include "config.php";
define('APPLICATION_NAME', 'Gmail API Quickstart');
define('CLIENT_SECRET_PATH', 'client_secret.json');
define('SCOPES', implode(' ', array(Google_Service_Gmail::GMAIL_READONLY)));
if (isset($_GET['action'])) {
    $action = $_GET['action'];
} else {
    $action = "none";
}
if (isset($_COOKIE['MoodleSession'])) {
    $userid = getMoodleIdFromSession($_COOKIE['MoodleSession']);
    //echo "User ID = $userid ";
    if (isStudent($userid)) {
        $userToken = getUserToken($userid);
        if (isset($userToken)) {
            printUnreadMessages($userToken);
        } else {
            if ($action == 'getToken') {
                getNewToken();
            } else {
                echo "0";
            }
        }
    } else {
        echo "null";
    }
}
// are stored in the config.php in the   //
// current directory                     //
//                                       //
/*****************************************/
include "config.php";
include "../config.php";
// Clean the data, make sure it only contains possible session information
if (preg_match('/^[a-z0-9]+$/', $_GET["session"])) {
    $session = $_GET["session"];
} else {
    $session = 0;
}
// ************************************************************
// Main Program Logic
// ************************************************************
$moodleId = getMoodleIdFromSession($session);
if (isStudent($moodleId)) {
    if (inCurrentCourse($moodleId) == 1) {
        $studentNumber = getStudentNumber($moodleId);
        $results = checkSurveyStatus($studentNumber);
    } else {
        $results = "0";
    }
} else {
    $results = "0";
}
echo $results;
// **************************************************************
// Supporting Functions
// **************************************************************
function getStudentNumber($moodleId)