<?php

namespace App\Services;

use App\Models\ProductSku;
use App\Models\User;
use App\Models\UserCoupon;
use Illuminate\Support\Collection;

class CouponService
{
    /**
     * 根据SKU商品获取可用优惠券
     *
     * @param User $user
     * @param array $skus 至少包含以下内容
     * [
     *      ['id', 'category_id', 'sell_price', 'vip_price', 'num']
     * ]
     * @return collection
     */
    public function availableCouponsToUser(User $user, array $skus): collection
    {
        //获取用户当前所有可用券
        $coupons = $this->userValidCoupons($user);

        $couponSkus = [];
        $availableCoupons = [];

        foreach ($coupons as $coupon) {
            if (!isset($couponSkus[$coupon->coupon_id])) {
                foreach ($skus as $sku) {
                    //这个商品是否在这个券的可用范围
                    if ($this->isAvailableCouponToSku($sku, $coupon)) {
                        //按coupon_id 分组商品
                        $couponSkus[$coupon->coupon_id][] = $sku;
                    }
                }
            }
        }

        foreach ($coupons as $coupon) {
            // 这个券是否有可用的商品
            if (isset($couponSkus[$coupon->coupon_id])) {
                //用户是否是vip
                if ($user->isVip()) {
                    $totalAmount = collect($couponSkus[$coupon->coupon_id])->sum(function ($item) {
                        return bcmul($item['vip_price'], $item['num']);
                    });
                } else {
                    $totalAmount = collect($couponSkus[$coupon->coupon_id])->sum(function ($item) {
                        return bcmul($item['sell_price'], $item['num']);
                    });
                }
                //针对这个券，可用的商品合计价格是否满足使用门槛
                if ($totalAmount >= $coupon->coupon_threshold) {
                    $availableCoupons[] = $coupon;
                }
            }
        }

        return collect($availableCoupons);
    }

    /**
     * 用户有效的优惠券
     *
     * @param User $user
     * @return collection
     */
    public function userValidCoupons(User $user): collection
    {
        return UserCoupon::with('ranges')->where([
            'user_id'=>$user->id,
        ])->onlyUnuse()->get();
    }

    /**
     * 这批商品中，这个券是否可用
     *
     * @return boolean
     */
    protected function isAvailableCouponToSomeSku(collection $skus, UserCoupon $coupon)
    {
        $res = false;
        foreach ($skus as $sku) {
            if ($sku instanceof ProductSku && $this->isAvailableCouponToSku($sku, $coupon)) {
                $res = true;
                break;//提前退出循环
            }
        }
        return $res;
    }

    /**
     * 这个商品是否可用这个券
     *
     * @param array $productSku ['id', 'category_id', 'sell_price', 'vip_price', 'num']
     * @param Coupon $coupon
     * @return boolean
     */
    protected function isAvailableCouponToSku($sku, UserCoupon $coupon)
    {
        $res = false;
        if ($coupon->ranges->count() == 0) {//如果没有规则则通用
            return true;
        }
        foreach ($coupon->ranges as $range) {
            switch ($range->type) {
                case 1://指定商品分类
                    if (in_array($sku['category_id'], explode(',', $range->ranges))) {
                        $res = true;
                    }
                    break;
                case 2://指定商品IDS
                    if (in_array($sku['id'], explode(',', $range->ranges))) {
                        $res = true;
                    }
                    break;
            }
            if ($res) {//如果可用提前跳出循环；
                break;
            }
        }
        return $res;
    }
}