server/app/service/util/trade.js

'use strict';
const { CrudService } = require('naf-framework-mongoose-free/lib/service');
const { BusinessError, ErrorCode } = require('naf-core').Error;
const _ = require('lodash');
const assert = require('assert');

//
class TradeService extends CrudService {
  constructor(ctx) {
    super(ctx, 'trade');
    this.redis = this.app.redis;
    this.redisKey = this.app.config.redisKey;
    this.redisTimeout = this.app.config.redisTimeout;
    this.shopModel = this.ctx.model.Shop.Shop;
    this.goodsModel = this.ctx.model.Shop.Goods;
    this.goodsSpecModel = this.ctx.model.Shop.GoodsSpec;
    this.cartModel = this.ctx.model.Trade.Cart;
  }
  /**
   * 检查选中的购物车是否符合购买的条件
   * @param {Object} body 请求体
   * @param body.cartIds 选中的购物车id列表
   * @param {Boolean} makeCache 生成缓存
   */
  async checkCartBuy({ cartIds }, makeCache = true) {
    const list = await this.cartModel.find({ _id: cartIds });
    let result = { result: true };
    for (const i of list) {
      const res = await this.checkCanBuy(i, false);
      if (res.result !== true) {
        result = res;
        break;
      }
    }

    if (makeCache) {
      const key = await this.makeOrderKey(cartIds);
      result.key = key;
    }

    return result;
  }

  /**
   * 检测是否可以购买该物品
   * @param {Object} param 查询条件
   * @param param.shop 商店id
   * @param param.goods 商品id
   * @param param.goodsSpec 商品规格id
   * @param param.num 购买数量
   * @param makeCache 生成缓存
   */
  async checkCanBuy({ shop, goods, goodsSpec, num }, makeCache = true) {
    assert(shop, '缺少店铺信息');
    assert(goods, '缺少商品信息');
    assert(goodsSpec, '缺少商品规格信息');
    assert(num, '缺少购买数量');
    const result = { result: true };
    // 1.检查商店是否正常运行
    const shopData = await this.shopModel.findById(shop);
    const shopRes = this.checkShop(shopData);
    if (shopRes.result !== true) return shopRes;
    // 2.检查商品是否可以购买
    const goodsData = await this.goodsModel.findById(goods);
    const goodsRes = this.checkGoods(goodsData);
    if (shopRes.result !== true) return goodsRes;
    // 3.检验该规格是否可以购买
    const goodsSpecData = await this.goodsSpecModel.findById(goodsSpec);
    const gsRes = this.checkGoodsSpec(goodsSpecData, num);
    if (gsRes.result !== true) return gsRes;
    if (makeCache) {
      const key = await this.makeOrderKey({ shop, goods, goodsSpec, num });
      result.key = key;
    }

    return result;
  }
  /**
   * 检查商店是否满足条件
   * @param {Object} shopData 店铺数据
   */
  checkShop(shopData) {
    const result = { result: true };
    if (!shopData) {
      result.msg = '未找到店铺';
      result.result = false;
      return result;
    }
    if (shopData.status !== '1') {
      result.msg = '店铺不处于营业状态';
      result.result = false;
      return result;
    }
    return result;
  }

  /**
   * 检查商品是否满足条件
   * @param {Object} goodsData 商品数据
   */
  checkGoods(goodsData) {
    const result = { result: true };
    if (!goodsData) {
      result.msg = '未找到商品';
      result.result = false;
      return result;
    }
    if (goodsData.status === '0') {
      result.msg = '该商品已下架';
      result.result = false;
      return result;
    }
    return result;
  }
  /**
   * 检查商品的规格是否满足购买条件
   * @param {Object} goodsSpecData 商品规格的数据
   * @param {Number} num 购买数量
   */
  checkGoodsSpec(goodsSpecData, num) {
    const result = { result: true };
    if (!goodsSpecData) {
      result.msg = '未找到商品的指定规格';
      result.result = false;
      return result;
    }
    if (goodsSpecData.status !== '0') {
      result.msg = '该规格的商品已下架';
      result.result = false;
      return result;
    }
    if (goodsSpecData.num < num) {
      result.msg = '库存量不足';
      result.result = false;
      return result;
    }
    return result;
  }

  // 随机字符串产生函数
  createNonceStr() {
    return Math.random().toString(36).substr(2, 15);
  }

  // 生成key
  async makeOrderKey(data) {
    const str = this.createNonceStr();
    const key = `${this.redisKey.orderKeyPrefix}${str}`;
    const value = JSON.stringify(data);
    await this.redis.set(key, value, 'EX', this.redisTimeout);
    return str;
  }
}

module.exports = TradeService;