<?php

namespace App\Services;

use App\Models\User;

class CouponService
{
    /**
     * 根据SKU商品获取可用优惠券
     *
     * @param User $user
     * @param array $products 至少包含以下内容
     *  [
     *      ['sku' => 商品SKU, 'quantity' => 10]
     *  ]
     * @return array
     */
    public function getAvailableCoupons(User $user, array $products): array
    {
        $coupons = $user->coupons()->onlyAvailable()->get();

        $coupons->load(['ranges' => function ($query) {
            $query->isEnable();
        }]);

        $availableCoupons = [];

        foreach ($coupons as $coupon) {
            // 是否满足券使用规则
            $passes = false;

            // 可用优惠券的商品的总额
            $amount = 0;

            foreach ($products as $product) {
                $sku = $product['sku'];

                if ($coupon->isSupport($sku)) {
                    $passes = true;

                    $amount += $sku->getRealPrice($user) * $product['quantity'];
                }
            }

            if ($passes && $amount >= $coupon->coupon_threshold) {
                $availableCoupons[] = $coupon;
            }
        }

        return $availableCoupons;
    }
}