public function getBasePriceForCurrency(ProductInterface $product, $currency = null)
    {
        $currency = $currency ?: $this->defaultCurrency;
        if ($prices = $product->getPrices()) {
            foreach ($prices as $price) {
                if ($price->getCurrency()->getCode() == $currency && $price->getMinimumQuantity() == 0) {
                    return $price;
                }
            }
        }

        return null;
    }