public function startShopSession()
 {
     if (Shop::getInstance()->isShopUser()) {
         if (AuthController::setShopSession()) {
             Shop::setShopSession($_GET['id_shop']);
             header('Location: home.php');
             exit;
         }
     }
     header('Location: shop_selection.php?errorMessage=accessDenied');
     exit;
 }