<?php

namespace App\Services;

use App\Exceptions\BizException;
use App\Models\BargainOrder;
use App\Models\BargainOrderLog;
use App\Models\BargainSku;
use App\Models\ProductSku;
use App\Models\User;
use Illuminate\Support\Arr;

class BargainService
{
    /**
     * 创建砍价单
     *
     * @param User $user
     * @param ProductSku $productSku
     * @return void
     */
    public function createBargainOrder(User $user, ProductSku $productSku)
    {
        $bargainSku = BargainSku::with(['activity'=>function ($query) {
            return $query->where('is_enable', true)->where('start_at', '<=', now())->where('end_at', '>=', now());
        }])->where('sku_id', $productSku->id)->first();
        if (!($bargainSku && $bargainSku->activity)) {
            throw new BizException('砍价商品活动已结束');
        }

        $order = new BargainOrder();
        $order->activity_id = $bargainSku->activity_id;
        $order->user_id = $user->id;
        $order->sku_id = $productSku->id;
        $order->sku_price = $productSku->getRealPrice($user);
        $order->status = BargainOrder::ORDER_STATUS_START;
        $order->expire_at = now()->addHours($bargainSku->activity->expire_hours);
        $order->save();

        return $order;
    }

    /**
     * 用户砍价
     *
     * @param User $user
     * @param BargainOrder $order
     * @return void
     */
    public function bargain(User $user, BargainOrder $order)
    {
        $order->lockForUpdate();
        $order->load('sku');

        //不能给自己砍
        if ($user->id == $order->user_id) {
            throw new BizException('不能帮自己砍价');
        }

        //已砍完
        if ($order->isFinished()) {
            throw new BizException('当前砍价单已完成，无法再砍');
        }

        //已下单
        if ($order->order_id > 0) {
            throw new BizException('当前砍价单下单，无法再砍');
        }

        //砍价超时
        if ($order->expire_at < now()) {
            throw new BizException('当前砍价已结束，无法再砍');
        }

        //如果砍价活动结束了，也不能砍了
        $activity = $order->sku->isBargaing();
        if (!$activity) {
            throw new BizException('当前砍价已结束，无法再砍');
        }

        //如果已经砍过了，不能再砍了
        if ($order->logs()->where('user_id', $user->id)->exists()) {
            throw new BizException('您已砍价');
        }

        //执行砍价动作;
        //计算第几次砍价，并获得当前砍价金额
        $nowBargainCount = $order->logs->count();

        $bargainRules = json_decode($activity->rules, true);

        $log = new BargainOrderLog([
            'user_id'=>$user->id,
            'bargain_amount'=> bcmul(Arr::get($bargainRules, $nowBargainCount, 0), 100),
        ]);

        $order->logs()->save($log);
        $order->bargain_price += $log->bargain_amount;
        if ($activity->times > 0 && $activity->times <= ($nowBargainCount ++)) {
            $order->status = BargainOrder::ORDER_STATUS_FINISHED;
        }
        $order->save();

        return $order;
    }
}