how can i put file to a certain google drive account? - php

Question

I'm using PHP to put some runtime created files on a specific Google Drive account.
If I'm logged on google with an account and I launch my script, these files will be uploaded on this account, even I use client ID and secret of a different account
Use case:
I'm logged with a#gmail.com, I use my script and files are sent to a#gmail.com's Google Drive instead of b#gmail.com's Google Drive
How can I upload these files to b#gmail.com account even if I'm logged with a#gmail.com account?
Thanks
The ex. 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(/*client id*/);
$drive->setClientSecret(/*client secret*/);
$drive->setRedirectUri(/*redirect uri (the same URI in the API configuration)*/);
$drive->setScopes(array('https://www.googleapis.com/auth/drive'));
$gdrive = new Google_DriveService($drive);
file_put_contents('token.json', $drive->authenticate());
$drive->setAccessToken(file_get_contents('token.json'));
$file = new Google_DriveFile();
$file->setTitle('My document');
$file->setDescription('A test document');
$file->setMimeType('text/plain');
$createdFile = $service->files->insert($file, array(
'data' => 'example',
'mimeType' => 'text/plain',
));
return true;
EDIT:
I use pathfinder solution and create a service account.
It seems working but I've still a problem: at the end of execution I can't find my file on gDrive...maybe I've done an invomplete configuration, even if I read the doc...
This is the code:
<?php
require_once 'google-api-php-client/src/Google_Client.php';
require_once 'google-api-php-client/src/contrib/Google_DriveService.php';
require_once 'google-api-php-client/src/contrib/Google_Oauth2Service.php';
$DRIVE_SCOPE = 'https://www.googleapis.com/auth/drive';
$SERVICE_ACCOUNT_EMAIL = '<email_in_api_access>#developer.gserviceaccount.com';
$SERVICE_ACCOUNT_PKCS12_FILE_PATH = 'google-api-phpclient/<api_key_file>-privatekey.p12';
$key = file_get_contents($SERVICE_ACCOUNT_PKCS12_FILE_PATH);
$auth = new Google_AssertionCredentials(
$SERVICE_ACCOUNT_EMAIL,
array($DRIVE_SCOPE),
$key);
$client = new Google_Client();
$client->setUseObjects(true);
$client->setAssertionCredentials($auth);
$gdrive = new Google_DriveService($client);
$file = new Google_DriveFile();
$file->setTitle('My document');
$file->setDescription('A test document');
$file->setMimeType('text/plain');
$createdFile = $gdrive->files->insert($file, array(
'data' => 'A test document',
'mimeType' => 'text/plain',
));
return true;