use Bitrix\Sale\Compatible\DiscountCompatibility;
use Bitrix\Sale\Basket;
use Bitrix\Sale\Discount\Gift;
use Bitrix\Sale\Fuser;

class DiscountsHelper
{
    /**
     * Возвращает массив id всех доступных подарков для товара
     *
     * @param int $productId - идентификатор товара
     * @return array - массив с id подарков для товара
     */
    public static function getGiftIds($productId)
    {
        $giftProductIds = [];

        if (!$productId) {
            return $giftProductIds;
        }

        DiscountCompatibility::stopUsageCompatible();

        $giftManager = Gift\Manager::getInstance();

        $potentialBuy = [
            'ID'                     => $productId,
            'MODULE'                 => 'catalog',
            'PRODUCT_PROVIDER_CLASS' => 'CCatalogProductProvider',
            'QUANTITY'               => 1,
        ];

        $basket = Basket::loadItemsForFUser(Fuser::getId(), SITE_ID);
        
        $basketPseudo = $basket->copy();

        foreach ($basketPseudo as $basketItem) {
            $basketItem->delete();
        }

        $collections = $giftManager->getCollectionsByProduct($basketPseudo, $potentialBuy);

        foreach ($collections as $collection) {
            /** @var \Bitrix\Sale\Discount\Gift\Gift $gift */
            foreach ($collection as $gift) {
                $giftProductIds[] = $gift->getProductId();
            }
        }

        DiscountCompatibility::revertUsageCompatible();

        return $giftProductIds;
    }
}

AddEventHandler('main', 'OnBuildGlobalMenu', 'addMenuItem');

function addMenuItem(&$aGlobalMenu, &$aModuleMenu)
{
    global $USER;

    if ($USER->IsAdmin()) {

        $aGlobalMenu['global_menu_custom'] = [
            'menu_id' => 'custom',
            'text' => 'Bitrix Studio',
            'title' => 'Bitrix Studio',
            'url' => 'settingss.php?lang=ru',
            'sort' => 1000,
            'items_id' => 'global_menu_custom',
            'help_section' => 'custom',
            'items' => [
                [
                    'parent_menu' => 'global_menu_custom',
                    'sort'        => 10,
                    'url'         => 'your_new_page.php?lang=ru',
                    'text'        => 'your_new_page',
                    'title'       => 'your_new_page',
                    'icon'        => 'fav_menu_icon',
                    'page_icon'   => 'fav_menu_icon',
                    'items_id'    => 'menu_custom',
                ],
                [
                    'parent_menu' => 'global_menu_custom',
                    'sort'        => 20,
                    'url'         => 'your_new_page_2.php?lang=ru',
                    'text'        => 'your_new_page_2',
                    'title'       => 'your_new_page_2',
                    'icon'        => 'fav_menu_icon_2',
                    'page_icon'   => 'fav_menu_icon_2',
                    'items_id'    => 'menu_custom',
                ],
            ],
        ];

    }
}