const express = require('express');
const router = express.Router();
const dbConnector = require('../utils/dbConnector');

// 获取用户购物车
router.get('/', async (req, res) => {
  try {
    const userId = req.user.id;
    
    const cartItems = await dbConnector.query(`
      SELECT ci.*, p.name as product_name, p.price, p.image as product_image, p.stock
      FROM cart_items ci
      JOIN products p ON ci.product_id = p.id
      WHERE ci.user_id = ?
    `, [userId]);
    
    const totalAmount = cartItems.reduce((sum, item) => sum + (item.price * item.quantity), 0);
    const totalQuantity = cartItems.reduce((sum, item) => sum + item.quantity, 0);
    
    res.json({
      code: 200,
      message: '获取成功',
      data: {
        items: cartItems,
        total_amount: totalAmount,
        total_quantity: totalQuantity
      }
    });
  } catch (error) {
    console.error('获取购物车失败:', error);
    res.status(500).json({
      code: 500,
      message: '服务器内部错误',
      error: error.message
    });
  }
});

// 添加商品到购物车
router.post('/items', async (req, res) => {
  try {
    const { product_id, quantity } = req.body;
    const userId = req.user.id;
    
    // 检查商品是否存在
    const product = await dbConnector.query('SELECT * FROM products WHERE id = ? AND status = 1', [product_id]);
    if (product.length === 0) {
      return res.status(404).json({
        code: 404,
        message: '商品不存在'
      });
    }
    
    // 检查购物车是否已有该商品
    const existingItem = await dbConnector.query(
      'SELECT * FROM cart_items WHERE user_id = ? AND product_id = ?',
      [userId, product_id]
    );
    
    if (existingItem.length > 0) {
      // 更新数量
      await dbConnector.query(
        'UPDATE cart_items SET quantity = quantity + ?, updated_at = NOW() WHERE id = ?',
        [quantity, existingItem[0].id]
      );
    } else {
      // 新增商品
      await dbConnector.query(
        'INSERT INTO cart_items (user_id, product_id, quantity, created_at, updated_at) VALUES (?, ?, ?, NOW(), NOW())',
        [userId, product_id, quantity]
      );
    }
    
    res.json({
      code: 200,
      message: '添加成功',
      data: {
        cart_item_id: existingItem.length > 0 ? existingItem[0].id : null
      }
    });
  } catch (error) {
    console.error('添加购物车失败:', error);
    res.status(500).json({
      code: 500,
      message: '服务器内部错误',
      error: error.message
    });
  }
});

// 更新购物车商品数量
router.put('/items/:id', async (req, res) => {
  try {
    const { id } = req.params;
    const { quantity } = req.body;
    const userId = req.user.id;
    
    // 检查购物车项是否存在
    const cartItem = await dbConnector.query(
      'SELECT * FROM cart_items WHERE id = ? AND user_id = ?',
      [id, userId]
    );
    
    if (cartItem.length === 0) {
      return res.status(404).json({
        code: 404,
        message: '购物车项不存在'
      });
    }
    
    await dbConnector.query(
      'UPDATE cart_items SET quantity = ?, updated_at = NOW() WHERE id = ?',
      [quantity, id]
    );
    
    res.json({
      code: 200,
      message: '更新成功'
    });
  } catch (error) {
    console.error('更新购物车失败:', error);
    res.status(500).json({
      code: 500,
      message: '服务器内部错误',
      error: error.message
    });
  }
});

// 删除购物车商品
router.delete('/items/:id', async (req, res) => {
  try {
    const { id } = req.params;
    const userId = req.user.id;
    
    await dbConnector.query(
      'DELETE FROM cart_items WHERE id = ? AND user_id = ?',
      [id, userId]
    );
    
    res.json({
      code: 200,
      message: '删除成功'
    });
  } catch (error) {
    console.error('删除购物车失败:', error);
    res.status(500).json({
      code: 500,
      message: '服务器内部错误',
      error: error.message
    });
  }
});

module.exports = router;