private Double getPrice(Basket basket) {
        double price = 0.0;
        int howMany = 0;

        List<Product> products = basket.getProducts();
        if (products == null || products.isEmpty()) {
            return price;
        }

        for (Product product : products) {
            howMany++;

            if (! (isBlackFriday() && (howMany % 3 == 0))) {
                price += product.getPriceWithVAT();
            }
        }

        if (howMany >= 10 && howMany < 20) {
            price = price * DISCOUNT_FOR_MORE_THAN_10_PCS;
        } else if (howMany >= 20) {
            price = price * DISCOUNT_FOR_MORE_THAN_20_PCS;
        }

        return price;
    }