// Examples from https://github.com/googlesamples/apps-script-oauth2

/**
 * Create the OAuth2 service.
 */
function getDriveService() {
    return OAuth2.createService('drive')
        .setAuthorizationBaseUrl('https://accounts.google.com/o/oauth2/auth')
        .setTokenUrl('https://accounts.google.com/o/oauth2/token')
        .setClientId('xxx')
        .setClientSecret('yyy')
        .setCallbackFunction('authCallback')
        .setPropertyStore(PropertiesService.getUserProperties())
        .setScope('https://www.googleapis.com/auth/drive')
        .setParam('login_hint', Session.getActiveUser().getEmail())
        .setParam('access_type', 'offline')
        .setParam('approval_prompt', 'force');
}

/**
 * Handle the callback.
 */
function authCallback(request: any) {
    const driveService = getDriveService();
    const isAuthorized = driveService.handleCallback(request);
    Logger.log(isAuthorized ? 'success' : 'denied');
}