GET /actions/oneShipStation/orders/process?SS-UserName=username&SS-Password=wh@t3v3rthep@ssw0rd1s&action=export&start_date=07%2f10%2f2017+15%3a54&end_date=07%2f10%2f2017+15%3a59&page=1

public function actionProcess(array $variables=[]) {
    if (!$this->authenticate()) {
        throw new HttpException(401);
    }
    switch (craft()->request->getParam('action')) {
        case 'export':
            return $this->getOrders();
        case 'shipnotify':
            return $this->postShipment();
        default:
            throw new HttpException(400);
    }
}

/**
 * Authenticate the user using HTTP Basic auth. This is NOT using Craft's sessions/authentication.
 *
 * @return bool, true if successfully authenticated or false otherwise
 */
protected function authenticate() {
    $expectedUsername = craft()->plugins->getPlugin('oneshipstation')->getSettings()->oneshipstation_username;
    $expectedPassword = craft()->plugins->getPlugin('oneshipstation')->getSettings()->oneshipstation_password;
    $username = array_key_exists('PHP_AUTH_USER', $_SERVER) ? $_SERVER['PHP_AUTH_USER'] : null;
    $password = array_key_exists('PHP_AUTH_PW', $_SERVER) ? $_SERVER['PHP_AUTH_PW'] : null;

    return $expectedUsername == $username && $expectedPassword == $password;
}
/**
 * Renders a big XML file of all orders in a format described by ShipStation
 * Note: this should probably get orders using Craft Commerce's variable/service if possible
 *
 * @param DateTime $start
 * @param DateTime $end
 *
 * @return Commerce_OrderModel[]|null
 */
protected function getOrders() {
    $criteria = craft()->elements->getCriteria('Commerce_Order');
    if ($start_date = $this->parseDate('start_date') && $end_date = $this->parseDate('end_date')) {
        $criteria->dateOrdered = array('and', '> '.$start_date, '< '.$end_date);
    }
    $criteria->orderStatusId = true;

    $num_pages = $this->paginateOrders($criteria);

    $parent_xml = new SimpleXMLElement('<Orders />');
    $parent_xml->addAttribute('pages', $num_pages);

    craft()->oneShipStation_xml->orders($parent_xml, $criteria->find());

    $this->returnXML($parent_xml);
}