<?php
declare(strict_types=1);

namespace Esun\CustomerCoupon\Model;

use Esun\CustomerCoupon\Api\CouponNotifierInterface;
use Esun\CustomerCoupon\Model\ResourceModel\Assignment as AssignmentResource;
use Magento\Framework\Exception\LocalizedException;
use Magento\SalesRule\Model\CouponFactory;

class AssignmentService
{
    public function __construct(
        private readonly AssignmentFactory $assignmentFactory,
        private readonly AssignmentResource $assignmentResource,
        private readonly CouponFactory $couponFactory,
        private readonly CouponNotifierInterface $couponNotifier
    ) {
    }

    /**
     * Assign generated coupon codes to customers.
     *
     * @param string[] $codes
     * @param int[] $customerIds
     * @param int $ruleId
     * @param string|null $source Stable source key used to make automatic grants idempotent
     */
    public function assignCodes(array $codes, array $customerIds, int $ruleId, ?string $source = null): void
    {
        if (count($codes) !== count($customerIds)) {
            throw new LocalizedException(__('The generated coupon count does not match the selected customer count.'));
        }

        $connection = $this->assignmentResource->getConnection();
        $assignmentIds = [];
        $connection->beginTransaction();
        try {
            foreach (array_values($codes) as $index => $code) {
                $coupon = $this->couponFactory->create()->load($code, 'code');
                if (!$coupon->getId()) {
                    throw new LocalizedException(__('The generated coupon "%1" could not be loaded.', $code));
                }

                $assignment = $this->assignmentFactory->create();
                $assignment->setData([
                    'coupon_id' => (int)$coupon->getId(),
                    'rule_id' => $ruleId,
                    'customer_id' => (int)$customerIds[$index],
                    'source' => $source,
                ]);
                $this->assignmentResource->save($assignment);
                $assignmentIds[] = (int)$assignment->getId();
            }
            $connection->commit();
        } catch (\Throwable $exception) {
            $connection->rollBack();
            throw $exception;
        }

        foreach ($assignmentIds as $assignmentId) {
            try {
                $this->couponNotifier->notify($assignmentId);
            } catch (\Throwable) {
                // Notification delivery is best-effort and must not invalidate an assigned coupon.
            }
        }
    }
}