OAuth 2.0 google - php

Question

I'm trying to create an authentication with google API. I always get my page refreshed I can't get access to the user information I see always the two alerts "here 1" and "here 2" any idea to help ?
<?php
/* GOOGLE LOGIN BASIC - Tutorial
* file - index.php
* Developer - Krishna Teja G S
* Website - http://packetcode.com/apps/google-login/
* Date - 28th Aug 2015
* license - GNU General Public License version 2 or later
*/
// REQUIREMENTS - PHP v5.3 or later
// Note: The PHP client library requires that PHP has curl extensions configured.
/*
* DEFINITIONS
*
* load the autoload file
* define the constants client id,secret and redirect url
* start the session
*/
require_once __DIR__.'/gplus-lib/vendor/autoload.php';
const CLIENT_ID = 'my code';
const CLIENT_SECRET = 'my code';
const REDIRECT_URI = 'http://www.servicebigdeals.com/google-login/';
session_start();
/*
* INITIALIZATION
*
* Create a google client object
* set the id,secret and redirect uri
* set the scope variables if required
* create google plus object
*/
$client = new Google_Client();
$client->setClientId(CLIENT_ID);
$client->setClientSecret(CLIENT_SECRET);
$client->setRedirectUri(REDIRECT_URI);
$client->setScopes('email');
$plus = new Google_Service_Plus($client);
/*
* PROCESS
*
* A. Pre-check for logout
* B. Authentication and Access token
* C. Retrieve Data
*/
/*
* A. PRE-CHECK FOR LOGOUT
*
* Unset the session variable in order to logout if already logged in
*/
if (isset($_REQUEST['logout'])) {
session_unset();
}
/*
* B. AUTHORIZATION AND ACCESS TOKEN
*
* If the request is a return url from the google server then
* 1. authenticate code
* 2. get the access token and store in session
* 3. redirect to same url to eliminate the url variables sent by google
*/
if (isset($_GET['code'])) {
$client->authenticate($_GET['code']);
$_SESSION['access_token'] = $client->getAccessToken();
$redirect = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
header('Location: ' . filter_var($redirect, FILTER_SANITIZE_URL));
}
else {
echo "<script>alert(\"here 1 \")</script>";
}
/*
* C. RETRIEVE DATA
*
* If access token if available in session
* load it to the client object and access the required profile data
*/
if (isset($_SESSION['access_token']) && $_SESSION['access_token']) {
$client->setAccessToken($_SESSION['access_token']);
$me = $plus->people->get('me');
// Get User data
$id = $me['id'];
$name = $me['displayName'];
$email = $me['emails'][0]['value'];
$profile_image_url = $me['image']['url'];
$cover_image_url = $me['cover']['coverPhoto']['url'];
$profile_url = $me['url'];
}
else {
echo "<script>alert(\"here 2 \")</script>";
// get the login url
$authUrl = $client->createAuthUrl();
}
?>
<!-- HTML CODE with embedded PHP-->
<div>
<?php
/*
* If login url is there then display login button
* else print the retrieved data
*/
if (isset($authUrl)) {
echo "<a class='login' href='" . $authUrl . "'><img src='gplus-lib/signin_button.png' height='50px'/></a>";
} else {
print "ID: {$id} <br>";
print "Name: {$name} <br>";
print "Email: {$email } <br>";
print "Image : {$profile_image_url} <br>";
print "Cover :{$cover_image_url} <br>";
print "Url: {$profile_url} <br><br>";
echo "<a class='logout' href='?logout'><button>Logout</button></a>";
}
?>
</div>