<?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 collection $skus
     * @return collection
     */
    public function availableCouponsToUser(User $user, collection $skus): collection
    {
        //获取用户当前所有可用券
        $coupons = $this->userValidCoupons($user);
        //判断券在这批商品中是否可用
        $availableCouponIds = [];
        $availableCoupons = [];
        foreach ($coupons as $coupon) {
            if (in_array($coupon->coupon_id, $availableCouponIds)) {//遇到同样的券ID时直接跳过
                $availableCoupons[] = $coupon;
            } else {
                if ($this->isAvailableCouponToSomeSku($skus, $coupon)) {
                    $availableCouponIds[] = $coupon->coupon_id;
                    $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,
            'status'=>0,
        ])->where('use_start_at', '<=', now())->where('use_end_at', '>=', now())->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 ProductSku $productSku
     * @param Coupon $coupon
     * @return boolean
     */
    protected function isAvailableCouponToSku(ProductSku $sku, UserCoupon $coupon)
    {
        $res = false;
        foreach ($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;
    }
}