优惠券微服务-C端领劵接口核心校验业务逻辑开发

    /**
     * 领取优惠券
     * @param couponId
     * @return
     */
    @ApiOperation("领取优惠券")
    @GetMapping("/add/promotion/{coupon_id}")
    public JsonData addPromotionCoupon(@ApiParam(value = "优惠券id",required = true) @PathVariable("coupon_id")long couponId){


        JsonData jsonData = couponService.addCoupon(couponId, CouponCategoryEnum.PROMOTION);

        return jsonData;
    }

    /**
     * 领取优惠券接口
     * @param couponId
     * @param category
     * @return
     */
    JsonData addCoupon(long couponId, CouponCategoryEnum category);

  /**
     * 领劵接口
     * 1、获取优惠券是否存在
     * 2、校验优惠券是否可以领取：时间、库存、超过限制
     * 3、扣减库存
     * 4、保存领劵记录
     *
     * 始终要记得，羊毛党思维很厉害，社会工程学 应用的很厉害
     *
     * @param couponId
     * @param category
     * @return
     */
    @Override
    public JsonData addCoupon(long couponId, CouponCategoryEnum category) {

        LoginUser loginUser = LoginInterceptor.threadLocal.get();

        CouponDO couponDO = couponMapper.selectOne(new QueryWrapper<CouponDO>()
                .eq("id",couponId)
                .eq("category",category.name()));


        //优惠券是否可以领取
        this.checkCoupon(couponDO,loginUser.getId());


        //构建领劵记录
        CouponRecordDO couponRecordDO = new CouponRecordDO();
        BeanUtils.copyProperties(couponDO,couponRecordDO);
        couponRecordDO.setCreateTime(new Date());
        couponRecordDO.setUseState(CouponStateEnum.NEW.name());
        couponRecordDO.setUserId(loginUser.getId());
        couponRecordDO.setUserName(loginUser.getName());
        couponRecordDO.setCouponId(couponId);
        couponRecordDO.setId(null);


        //扣减库存  TODO
        int rows = 1; //couponMapper.reduceStock(couponId);

        if(rows==1){
            //库存扣减成功才保存记录
            couponRecordMapper.insert(couponRecordDO);

        }else {
            log.warn("发放优惠券失败:{},用户:{}",couponDO,loginUser);


            throw  new BizException(BizCodeEnum.COUPON_NO_STOCK);
        }

        return JsonData.buildSuccess();
    }


    /**
     * 校验是否可以领取
     * @param couponDO
     * @param userId
     */
    private void checkCoupon(CouponDO couponDO, Long userId) {

        if(couponDO==null){
            throw new BizException(BizCodeEnum.COUPON_NO_EXITS);
        }

        //库存是否足够
        if(couponDO.getStock()<=0){
            throw new BizException(BizCodeEnum.COUPON_NO_STOCK);
        }

        //判断是否是否发布状态
        if(!couponDO.getPublish().equals(CouponPublishEnum.PUBLISH.name())){
            throw new BizException(BizCodeEnum.COUPON_GET_FAIL);
        }

        //是否在领取时间范围
        long time = CommonUtil.getCurrentTimestamp();
        long start = couponDO.getStartTime().getTime();
        long end = couponDO.getEndTime().getTime();
        if(time<start || time>end){
            throw new BizException(BizCodeEnum.COUPON_OUT_OF_TIME);
        }

        //用户是否超过限制
        int recordNum =  couponRecordMapper.selectCount(new QueryWrapper<CouponRecordDO>()
                .eq("coupon_id",couponDO.getId())
                .eq("user_id",userId));

        if(recordNum >= couponDO.getUserLimit()){
            throw new BizException(BizCodeEnum.COUPON_OUT_OF_LIMIT);
        }




    }

public enum  CouponStateEnum {

    /**
     * 新的可用
     */
    NEW,

    /**
     * 已经使用
     */
    USED,

    /**
     * 过期
     */
    EXPIRED

}