inklabs/kommerce-core

<?php
namespace inklabs\kommerce\Lib;

use inklabs\kommerce\Entity\Cart;
use inklabs\kommerce\Entity\CartTotal;

class CartCalculator implements CartCalculatorInterface
{
    /** @var Cart */
    protected $cart;

    /** @var Pricing */
    protected $pricing;

    /** @var CartTotal */
    protected $cartTotal;

    public function __construct(Pricing $pricing)
    {
        $this->pricing = $pricing;
    }

    /**
     * This is not the PricingInterface. CartCalculator is coupled to the Pricing implementation
     * @return Pricing
     */
    public function getPricing()
    {
        return $this->pricing;
    }

    public function getTotal(Cart $cart): CartTotal
    {
        $this->cart = $cart;

        $this->cartTotal = new CartTotal();

        $this->calculateItemPrices();
        $this->calculateCartPriceRules();
        $this->calculateShippingPrice();
        $this->calculateCouponDiscounts();
        $this->calculateTaxes();

        $this->calculateTotal();
        $this->calculateSavings();

        return $this->cartTotal;
    }

    private function calculateItemPrices(): void
    {
        foreach ($this->cart->getCartItems() as $item) {
            $price = $item->getPrice($this->pricing);

            $this->cartTotal->origSubtotal += $price->origQuantityPrice;
            $this->cartTotal->subtotal += $price->quantityPrice;

            if ($item->getProduct()->isTaxable()) {
                $this->cartTotal->taxSubtotal += $price->quantityPrice;
            }
        }
    }

    private function calculateCartPriceRules(): void
    {
        foreach ($this->pricing->getCartPriceRules() as $cartPriceRule) {
            if ($cartPriceRule->isValid($this->pricing->getDate(), $this->cart->getCartItems())) {
                $numberTimesToApply = $cartPriceRule->numberTimesToApply($this->cart->getCartItems());

                foreach ($cartPriceRule->getCartPriceRuleDiscounts() as $discount) {
                    $price = $this->pricing->getPrice($discount->getProduct(), $discount->getQuantity());
                    $discountValue = $price->quantityPrice;

                    $discountValue *= $numberTimesToApply;

                    $this->cartTotal->discount += $discountValue;

                    if ($cartPriceRule->getReducesTaxSubtotal() and $discount->getProduct()->isTaxable()) {
                        $this->cartTotal->taxSubtotal -= $discountValue;
                    }

                    $this->cartTotal->addCartPriceRule($cartPriceRule);
                }
            }
        }

        // No subtotal below zero!
        $this->cartTotal->subtotal = max(0, $this->cartTotal->subtotal);
    }

    private function calculateCouponDiscounts(): void
    {
        foreach ($this->cart->getCoupons() as $key => $coupon) {
            if ($coupon->isValid($this->pricing->getDate(), $this->cartTotal->subtotal)) {
                $newSubtotal = $coupon->getUnitPrice($this->cartTotal->subtotal);
                $discountValue = $this->cartTotal->subtotal - $newSubtotal;
                $this->cartTotal->discount += $discountValue;
                $this->cartTotal->coupons[$key] = $coupon;

                if ($coupon->getReducesTaxSubtotal()) {
                    $this->cartTotal->taxSubtotal -= $discountValue;
                }

                if ($coupon->getFlagFreeShipping()) {
                    $this->cartTotal->shippingDiscount = $this->cartTotal->shipping;
                    $this->cartTotal->discount += $this->cartTotal->shipping;
                }
            }
        }

        // No taxes below zero!
        $this->cartTotal->taxSubtotal = max(0, $this->cartTotal->taxSubtotal);
    }

    private function calculateShippingPrice(): void
    {
        $shipmentRate = $this->cart->getShipmentRate();
        if ($shipmentRate !== null) {
            $this->cartTotal->shipping = $shipmentRate->getRate()->getAmount();
        }
    }

    private function calculateTaxes(): void
    {
        $taxRate = $this->cart->getTaxRate();
        if ($taxRate !== null) {
            $this->cartTotal->tax = $taxRate->getTax(
                $this->cartTotal->taxSubtotal,
                ($this->cartTotal->shipping - $this->cartTotal->shippingDiscount)
            );

            if ($this->cartTotal->tax > 0) {
                $this->cartTotal->taxRate = $taxRate;
            }
        }
    }

    private function calculateTotal(): void
    {
        $this->cartTotal->total = (
            $this->cartTotal->subtotal
            - $this->cartTotal->discount
            + $this->cartTotal->shipping
            + $this->cartTotal->tax
        );

        // No total below zero!
        $this->cartTotal->total = max(0, $this->cartTotal->total);
    }

    private function calculateSavings(): void
    {
        $this->cartTotal->savings = (
            $this->cartTotal->origSubtotal
            - $this->cartTotal->subtotal
            + $this->cartTotal->discount
        );
    }
}