<?php

declare(strict_types=1);

namespace Mironsoft\Loyalty\Plugin\Checkout;

use Magento\Customer\Api\CustomerRepositoryInterface;
use Magento\Framework\Exception\LocalizedException;
use Magento\Quote\Model\Quote;
use Magento\Quote\Model\Quote\Address;
use Magento\Quote\Model\Quote\TotalsCollector;
use Mironsoft\Loyalty\Model\Config\LoyaltyConfig;
use Psr\Log\LoggerInterface;

/**
 * Reduces the quote address grand total by the euro value of any loyalty
 * points the customer has chosen to redeem for this order.
 */
class ApplyPointsRedemptionToTotalsPlugin
{
    /**
     * @param CustomerRepositoryInterface $customerRepository Loads the customer's current points balance.
     * @param LoyaltyConfig $loyaltyConfig Provides the points-per-euro conversion rate.
     * @param LoggerInterface $logger Logs unexpected lookup failures without breaking totals collection.
     */
    public function __construct(
        private readonly CustomerRepositoryInterface $customerRepository,
        private readonly LoyaltyConfig $loyaltyConfig,
        private readonly LoggerInterface $logger,
    ) {
    }

    /**
     * Applies the points-redemption discount to the already-collected totals.
     *
     * @param TotalsCollector $subject The intercepted totals collector instance.
     * @param Address $result Address with subtotal/shipping/tax/grand_total already computed.
     * @param Quote $quote The quote being totalled.
     * @param Address $address The quote address being totalled.
     * @return Address
     */
    public function afterCollectAddressTotals(
        TotalsCollector $subject,
        Address $result,
        Quote $quote,
        Address $address
    ): Address {
        $customerId = (int) $quote->getCustomerId();
        $pointsToRedeem = (int) $quote->getData('loyalty_points_to_redeem');

        if ($customerId <= 0 || $pointsToRedeem <= 0) {
            return $result;
        }

        try {
            $customer = $this->customerRepository->getById($customerId);
        } catch (LocalizedException $exception) {
            $this->logger->warning(
                'Loyalty: could not load customer for points redemption.',
                ['customer_id' => $customerId, 'exception' => $exception]
            );

            return $result;
        }

        $balanceAttribute = $customer->getCustomAttribute('loyalty_points_balance');
        $balance = $balanceAttribute !== null ? (int) $balanceAttribute->getValue() : 0;
        $redeemedPoints = min($pointsToRedeem, $balance);

        $pointsPerEuro = $this->loyaltyConfig->getPointsPerEuro();

        if ($redeemedPoints <= 0 || $pointsPerEuro <= 0.0) {
            return $result;
        }

        $discount = round($redeemedPoints / $pointsPerEuro, 2);
        $discount = min($discount, (float) $result->getGrandTotal());

        $result->setGrandTotal((float) $result->getGrandTotal() - $discount);
        $result->setBaseGrandTotal((float) $result->getBaseGrandTotal() - $discount);
        $result->setData('loyalty_points_redeemed', $redeemedPoints);
        $result->setData('loyalty_points_discount', $discount);

        return $result;
    }
}

<type name="Magento\Quote\Model\Quote\TotalsCollector">
    <plugin name="mironsoft_loyalty_apply_points_redemption_to_totals"
            type="Mironsoft\Loyalty\Plugin\Checkout\ApplyPointsRedemptionToTotalsPlugin"
            sortOrder="100"/>
</type>