const express = require('express');
const router = express.Router();
const { getDB } = require('../database');

/**
 * @swagger
 * /api/coupon:
 *   get:
 *     summary: 获取用户优惠券
 *     description: 返回用户所有优惠券，包含是否已领取状态
 *     tags: [coupon]
 *     parameters:
 *       - in: query
 *         name: user_id
 *         schema:
 *           type: string
 *         required: true
 *         description: 用户ID
 *     responses:
 *       200:
 *         description: 成功返回用户优惠券
 *         content:
 *           application/json:
 *             schema:
 *               type: object
 *               properties:
 *                 success:
 *                   type: boolean
 *                   example: true
 *                 data:
 *                   type: array
 *                   items:
 *                     type: object
 *                     properties:
 *                       id:
 *                         type: string
 *                         example: "1"
 *                       name:
 *                         type: string
 *                         example: "满减优惠券"
 *                       discount:
 *                         type: number
 *                         example: 100
 *                       remain:
 *                         type: number
 *                         example: 10
 *                       got:
 *                         type: boolean
 *                         example: false
 *                         description: 是否已领取
 * 
 *       400:
 *         description: 缺少用户ID参数
 *       500:
 *         description: 服务器内部错误
 */
router.get('/', async (req, res) => {
  try {
    const useId = req.query.user_id;
    const db = getDB();
    const query = `
      SELECT * FROM coupon_products
    `
    const [coupon] = await db.query(query);

    if (coupon.length === 0) {
      res.json({ message: '暂无优惠券' });
    }

    for(const item of coupon) {
      const query = `
        SELECT * FROM coupon_use WHERE user_id = ? AND coupon_id = ?
      `
      const [couponExist] = await db.query(query, [useId, item.id]);
      if (couponExist.length === 0) {
        item.got = false;
      } else {
        item.got = true;
      }
    }

    res.json({coupon, success: true});
  } catch (error) {
    res.status(500).json({ error: '获取优惠券失败' });
  }
});

/**
 * @swagger
 * /api/coupon/{id}:
 *   get:
 *     summary: 用户领取优惠券
 *     description: 用户通过优惠券ID领取优惠券，优惠券数量减一
 *     tags: [coupon]
 *     parameters:
 *       - in: path
 *         name: id
 *         schema:
 *           type: string
 *         required: true
 *         description: 用户ID
 *       - in: query
 *         name: coupon_id
 *         schema:
 *           type: string
 *         required: true
 *         description: 优惠券ID
 *     responses:
 *       200:
 *         description: 成功领取优惠券
 *         content:
 *           application/json:
 *             schema:
 *               type: object
 *               properties:
 *                 success:
 *                   type: boolean
 *                   example: true
 *       400:
 *         description: 缺少用户ID或优惠券ID参数
 *       500:
 *         description: 服务器内部错误
 */
router.get('/:id', async (req, res) => {
  try {
    const db = getDB();

    const userId = req.params.id;
    const receiveCouponId = req.query.coupon_id;

    const query = `
      SELECT * FROM coupon_use WHERE user_id = ? AND coupon_id = ?
    `
    const [couponExist] = await db.query(query, [userId, receiveCouponId]);

    if (couponExist.length === 0) {

      const insertQuery = `
        INSERT INTO coupon_use (user_id, coupon_id, get_time) VALUES (?, ?, now())
      `
      await db.query(insertQuery, [userId, receiveCouponId]);

      const updateQuery = `
        UPDATE coupon_products SET remain = remain - 1 WHERE id = ?
      `
      await db.query(updateQuery, [receiveCouponId]);

    } else {
      return res.status(500).json({ error: '已有该优惠券' });
    }

    res.json({success: true});
  } catch (error) {
    console.log(error);
    res.status(500).json({ error: '获取优惠券失败' });
  }
});

/**
 * @swagger
 * /api/coupon/user/{id}:
 *   get:
 *     summary: 获取用户优惠券
 *     description: 返回用户领取的优惠券，包括优惠券信息和商品信息
 *     tags: [coupon]
 *     parameters:
 *       - in: path
 *         name: id
 *         schema:
 *           type: string
 *         required: true
 *         description: 用户ID
 *     responses:
 *       200:
 *         description: 成功返回用户优惠券
 *         content:
 *           application/json:
 *             schema:
 *               type: object
 *               properties:
 *                 success:
 *                   type: boolean
 *                   example: true
 *                 data:
 *                   type: array
 *                   items:
 *                     type: object
 *                     properties:
 *                       id:
 *                         type: string
 *                         example: "1"
 *                       name:
 *                         type: string
 *                         example: "满减优惠券"
 *                       discount:
 *                         type: number
 *                         example: 100
 *                       products_id:
 *                         type: array
 *                         items:
 *                           type: string
 *                           example: "1"
 *                       remain:
 *                         type: number
 *                         example: 100
 *                       get_time:
 *                         type: string
 *                         format: date-time
 *                         example: "2023-01-01T00:00:00.000Z"
 *       400:
 *         description: 缺少用户ID参数
 *       500:
 *         description: 服务器内部错误
 */
router.get('/user/:id', async (req, res) => {
  try {
    const db = getDB();
    const userId = req.params.id;

    const query = `
      SELECT * FROM coupon_use WHERE user_id = ?
    `
    const [coupon] = await db.query(query, [userId]);

    for (const item of coupon) {
      const query = `
        SELECT * FROM coupon_products WHERE id = ?
      `
      const [couponInfo] = await db.query(query, [item.coupon_id]);
      item.couponInfo = couponInfo[0];
      item.couponInfo.products = [];
      for (const product of item.couponInfo.products_id) {
        const query = `
          SELECT name FROM products WHERE id = ?
        `
        const [productInfo] = await db.query(query, [product]);
        item.couponInfo.products.push(productInfo[0]);
      }
    }
    
    res.json({success: true, coupon});
  } catch (error) {
    console.log(error);
    res.status(500).json({ error: '加载优惠券失败' });
  }
})

module.exports = router;