How to refresh an expired token?

[mahdi-above]

I used the steps from this page to get the access token. Now I have the access token and refresh token.

How can you refresh the access_token using the refresh token?

googleapis/php-analytics-data@175f05d#top

$oauth = new OAuth2([
    'scope' => 'https://www.googleapis.com/auth/analytics.readonly',
    'tokenCredentialUri' => 'https://oauth2.googleapis.com/token',
    'authorizationUri' => $keys->{'web'}->{'auth_uri'},
    'clientId' => $keys->{'web'}->{'client_id'},
    'clientSecret' => $keys->{'web'}->{'client_secret'},
    'redirectUri' => 'http://' . $_SERVER['HTTP_HOST'] . '/',
]);

    $auth_url = $oauth->buildFullAuthorizationUri();
    header('Location: ' . filter_var($auth_url, FILTER_SANITIZE_URL));

    // If an OAuth2 authorization code is present in the URL, exchange it for
    // an access token.
    $oauth->setCode($_GET['code']);
    $oauth->fetchAuthToken();

    // Persist the acquired access token in a session.
    $_SESSION['access_token'] = $oauth->getAccessToken();

    // Refresh the current page.
    $redirect_uri = 'http://' . $_SERVER['HTTP_HOST'] . '/';
    header('Location: ' . filter_var($redirect_uri, FILTER_SANITIZE_URL));

Any suggestion?