refactor del la clase Order

Order.php

<?php

/**
 * Se aplico la técnica de extract method al metodo calculate dejandolo con 
 * la responsabilidad de solo hacer el calculo y dejandolo legible y eliminandole complejidad ciclica
 * 
 * Class Order
 */
class Order
{
    /**
     * @return float
     */
    public function calculate()
    {
        $details = $this->getDetail();
        $total = 0;
        foreach ($details as $detail) {
            $vat = $this->getVat($detail);
            $price = $this->getPrice($detail);
            $total += $price + ($price/100 * $vat->getValue());
        }
        $discountPercent = $this->getDiscountPercent($total);

        return $total - $discountPercent;
    }

    /**
     * @param $detail
     * @return mixed
     */
    public function getVat($detail)
    {
        return !$detail->hasVat() ? $this->getCustomer()->getVat() : $detail->getVat();
    }

    public function getPrice($detail)
    {
        return $detail->getAmount() * $detail->getPrice();
    }

    /**
     * @param $customer
     * @param $total
     * @return float
     */
    public function getDiscountPercentForCustomer($customer, $total)
    {
        if ($this->hasDiscount()) {
            return ($total/100) * $this->getDiscount();
        } elseif ($this->hasPercentDiscountForMaxAmount($customer, $total)) {
            return ($total/100) * $this->getDiscount($customer);
        }
    }

    /**
     * @param $customer
     * @param $total
     * @return bool
     */
    public function hasPercentDiscountForCustomerMaxAmount($customer, $total)
    {
        return $customer->hasDiscountForMaxAmount() && $total >= $customer->getDiscountForMaxAmount();
    }
}