<script src="https://apis.google.com/js/client:platform.js" async defer></script>
<span id="signinButton">
    <span
        class="g-signin"
        data-callback="signinCallback"
        data-clientid="XXX"
        data-cookiepolicy="single_host_origin"
        data-requestvisibleactions="http://schema.org/AddAction"
        data-scope="https://www.googleapis.com/auth/plus.login">
    </span>
</span>

<script>
function signinCallback(authResult) {
    if (authResult['status']['signed_in']) {
        document.getElementById('signinButton').setAttribute('style', 'display: none');
        $('#googletoken').val(JSON.stringify(gapi.auth.getToken()))
    }
}
</script>



<form method="post">
    <input type="hidden" name="action" value="google-login">
    <input type="hidden" name="googletoken" id="googletoken">
    <input type="submit" name="submit" value="submit google login">
</form>

include 'googleapiclient/src/Google/autoload.php';

$client = new Google_Client();
$client->setClientId($appId);
$client->setClientSecret($secret);
$client->setRedirectUri($redirect);

$token = $_POST['googletoken'];
$client->setAccessToken($token);
$token = json_decode($token, true);
$client->authenticate($token['code']);
$service = new Google_Service_Plus($client);

$me = $service->people->get('me');
print_r($me);