Automatically refresh token using google drive api with php script

I followed again THIS TUTORIAL to upload a file on Google Drive with php, directly from my REMOTE SERVER: so I have created new API Project from Google API Console, enabled Drive API service, requested OAuth Client ID and Client Secret, wrote them in a script, then upload it together with Google APIs Client Library for PHP folder to this http://www.MYSERVER.com/script1.php, to retrieve Auth code:

<?php

require_once 'google-api-php-client/src/Google_Client.php';
require_once 'google-api-php-client/src/contrib/Google_DriveService.php';

$drive = new Google_Client();

$drive->setClientId('XXX'); // HERE I WRITE MY Client ID

$drive->setClientSecret('XXX'); // HERE I WRITE MY Client Secret

$drive->setRedirectUri('urn:ietf:wg:oauth:2.0:oob');

$drive->setScopes(array('https://www.googleapis.com/auth/drive'));

$gdrive = new Google_DriveService($drive);

$url = $drive->createAuthUrl();
$authorizationCode = trim(fgets(STDIN));

$token = $drive->authenticate($authorizationCode);

?>

When I visit http://www.MYSERVER.com/script1.php I allow authorization and get the Auth code that I can write in a second script. Then I upload it to http://www.MYSERVER.com/script2.php, who looks like:

<?php

require_once 'google-api-php-client/src/Google_Client.php';
require_once 'google-api-php-client/src/contrib/Google_DriveService.php';

$drive = new Google_Client();

$drive->setClientId('X');  // HERE I WRITE MY Client ID
$drive->setClientSecret('X');  // HERE I WRITE MY Client Secret
$drive->setRedirectUri('urn:ietf:wg:oauth:2.0:oob');
$drive->setScopes(array('https://www.googleapis.com/auth/drive'));

$gdrive = new Google_DriveService($drive);

$_GET['code']= 'X/XXX'; // HERE I WRITE AUTH CODE RETRIEVED AFTER RUNNING REMOTE script.php

file_put_contents('token.json', $drive->authenticate());

$drive->setAccessToken(file_get_contents('token.json'));

$doc = new Google_DriveFile();

$doc->setTitle('Test Drive');
$doc->setDescription('Document');
$doc->setMimeType('text/plain');

$content = file_get_contents('drive.txt');

$output = $gdrive->files->insert($doc, array(
      'data' => $content,
      'mimeType' => 'text/plain',
    ));

print_r($output);

?>

Well, now the file drive.txt is uploaded on my Google Drive and structure of token.json file is a sort of:

{"access_token":"XXX","token_type":"Bearer","expires_in":3600,"refresh_token":"YYY","created":1365505148}

Now, as you can imagine I can call script2.php and upload file until a certain time. Finally, the point is: I don't want the token to expire, I don't want to allow authorization each time it expire (recalling script1.php): I need to call the script2.php periodically during the day, to upload my file automatically, without user interaction. So, what's the best way to automatically refresh the token forever in this context? Do I need another script? Can I add some code to script2.php? or modify the token.json file? And where can I read the time remaining before the token expire? Thanks!

You don't have to periodically ask for an access token. If you have a refresh_token, PHP client will automatically acquire a new access token for you.

In order to retrieve an refresh_token, you need to set access_type to "offline" and ask for offline access permissions:

$drive->setAccessType('offline');

Once you get a code,

$_GET['code']= 'X/XXX';
$drive->authenticate();

// persist refresh token encrypted
$refreshToken = $drive->getAccessToken()["refreshToken"];

For future requests, make sure that refreshed token is always set:

$tokens = $drive->getAccessToken();
$tokens["refreshToken"] = $refreshToken;
$drive->setAccessToken(tokens);

If you want a force access token refresh, you can do it by calling refreshToken:

$drive->refreshToken($refreshToken);

Beware, refresh_token will be returned only on the first $drive->authenticate(), you need to permanently store it. In order to get a new refresh_token, you need to revoke your existing token and start auth process again.

Offline access is explained in detail on Google's OAuth 2.0 documentation.

After messing a lot I got this to work. I am using one file/script to get the offline token and then a class to do stuff with the api:

require_once 'src/Google/autoload.php'; // load library

session_start();

$client = new Google_Client();
// Get your credentials from the console
$client->setApplicationName("Get Token");
$client->setClientId('...');
$client->setClientSecret('...');
$client->setRedirectUri('...'); // self redirect
$client->setScopes(array('https://www.googleapis.com/auth/drive.file'));
$client->setAccessType("offline");
$client->setApprovalPrompt('force'); 



if (isset($_GET['code'])) {
    $client->authenticate($_GET['code']);
    $_SESSION['token'] = $client->getAccessToken();
    $client->getAccessToken(["refreshToken"]);
    $redirect = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
    header('Location: ' . filter_var($redirect, FILTER_SANITIZE_URL));
    return;
}

if (isset($_SESSION['token'])) {
    $client->setAccessToken($_SESSION['token']);
}

if (isset($_REQUEST['logout'])) {
    unset($_SESSION['token']);
    $client->revokeToken();
}


?>
<!doctype html>
<html>
    <head><meta charset="utf-8"></head>
    <body>
        <header><h1>Get Token</h1></header>
        <?php
        if ($client->getAccessToken()) {
            $_SESSION['token'] = $client->getAccessToken();
            $token = json_decode($_SESSION['token']);
            echo "Access Token = " . $token->access_token . '<br/>';
            echo "Refresh Token = " . $token->refresh_token . '<br/>';
            echo "Token type = " . $token->token_type . '<br/>';
            echo "Expires in = " . $token->expires_in . '<br/>';
            echo "Created = " . $token->created . '<br/>';
            echo "<a class='logout' href='?logout'>Logout</a>";
            file_put_contents("token.txt",$token->refresh_token); // saving access token to file for future use
        } else {
            $authUrl = $client->createAuthUrl();
            print "<a class='login' href='$authUrl'>Connect Me!</a>";
        }
        ?>
    </body>
</html>

You can load refresh token from file and use it as necessary for offline access:

class gdrive{

function __construct(){
        require_once 'src/Google/autoload.php';
        $this->client = new Google_Client();
}

function initialize(){
        echo "initializing class\n";
        $client = $this->client;
        // credentials from google console
        $client->setClientId('...');
        $client->setClientSecret('...');
        $client->setRedirectUri('...');

        $refreshToken = file_get_contents(__DIR__ . "/token.txt"); // load previously saved token
        $client->refreshToken($refreshToken);
        $tokens = $client->getAccessToken();
        $client->setAccessToken($tokens);

        $this->doSomething(); // go do something with the api       
    }
}

More here: https://github.com/yannisg/Google-Drive-Uploader-PHP