Cara menggunakan token google dengan offline, di google dev console buat oaut 2 API untuk versi desktop. Kalau oauth versi web setelah login google akan diredirect

Access API Google Offline.php

<?php
    /**
     * check ke goole apakah sudah pernah login
     * init path ke secret & auth penggunaan offline apps
     */
    public function ajx_checkAuth()
    {
        $client = new Google_Client();
        $client->setApplicationName('MyAPP');
        $client->setScopes([
            "https://www.google.com/m8/feeds",
            "https://www.googleapis.com/auth/contacts"
        ]);
        $client->setAuthConfig($this->config->item("path_secret"));
        $client->setAccessType('offline');
        $client->setPrompt('select_account consent');

        $tokenPath = $this->config->item("path_token");
        if (file_exists($tokenPath)) {
            $accessToken = json_decode(file_get_contents($tokenPath), true);
            $client->setAccessToken($accessToken);
        }

        // If there is no previous token or it's expired.
        if ($client->isAccessTokenExpired()) {
            // Refresh the token if possible, else fetch a new one.
            if ($client->getRefreshToken()) {
                $client->fetchAccessTokenWithRefreshToken($client->getRefreshToken());
                echo json_encode(array("status"=>true)) ;
            } else {
                // Request authorization from the user.
                $url = $client->createAuthUrl();
                echo json_encode(array("url"=>trim($url),"status"=>false)) ;
            }

        }else{
            echo json_encode(array("status"=>true)) ;
        }
    }

    public function ajx_verifyAuth()
    {
        $client = new Google_Client();
        $client->setApplicationName('MyAPP');
        $client->setScopes([
            "https://www.google.com/m8/feeds",
            "https://www.googleapis.com/auth/contacts"
        ]);
        $client->setAuthConfig($this->config->item("path_secret"));
        $client->setAccessType('offline');
        $client->setPrompt('select_account consent');

        $tokenPath = $this->config->item("path_token");
        if (file_exists($tokenPath)) {
            $accessToken = json_decode(file_get_contents($tokenPath), true);
            $client->setAccessToken($accessToken);
        }

        // If there is no previous token or it's expired.
        if ($client->isAccessTokenExpired()) {
            // Refresh the token if possible, else fetch a new one.
            if ($client->getRefreshToken()) {
                $client->fetchAccessTokenWithRefreshToken($client->getRefreshToken());
            } else {
                // Request authorization from the user.
                // Exchange authorization code for an access token.
                $authCode = $this->input->post("code");
                $accessToken = $client->fetchAccessTokenWithAuthCode($authCode);
                $client->setAccessToken($accessToken);

                // Check to see if there was an error.
                if (array_key_exists('error', $accessToken)) {
                    throw new Exception(join(', ', $accessToken));
                }
            }
            // Save the token to a file.
            if (!file_exists(dirname($tokenPath))) {
                mkdir(dirname($tokenPath), 0700, true);
            }
            file_put_contents($tokenPath, json_encode($client->getAccessToken()));
        }

        return $client;
    }