<?
session_start();
require 'vendor/autoload.php'; // Include Google API Client

$client = new Google_Client();
$client->setClientId('YOUR_CLIENT_ID');
$client->setClientSecret('YOUR_CLIENT_SECRET');
$client->setRedirectUri('YOUR_REDIRECT_URI');
$client->addScope("email");
$client->addScope("profile");

if (isset($_GET['code'])) {
    $token = $client->fetchAccessTokenWithAuthCode($_GET['code']);
    $client->setAccessToken($token['access_token']);
    $oauth = new Google_Service_Oauth2($client);
    $userInfo = $oauth->userinfo->get();
    // Store user info in session or database
} else {
    $authUrl = $client->createAuthUrl();
    header('Location: ' . filter_var($authUrl, FILTER_SANITIZE_URL));
}
?>