// 数据库服务
const mysql = require('mysql2/promise');
const config = require('../config/config');

class DatabaseService {
  constructor() {
    this.connection = null;
  }

  // 连接数据库
  async connect() {
    try {
      this.connection = await mysql.createConnection({
        host: config.db.host,
        port: config.db.port,
        user: config.db.user,
        password: config.db.password,
        database: config.db.database
      });
      console.log('数据库连接成功');
      return this.connection;
    } catch (error) {
      console.error('数据库连接失败:', error.message);
      throw error;
    }
  }

  // 断开数据库连接
  async disconnect() {
    if (this.connection) {
      await this.connection.end();
      console.log('数据库连接已断开');
    }
  }

  // 查询需要同步的数据
  async getAllSyncData() {
    try {
      // 根据配置决定是查询所有数据还是仅未同步数据
      let usersQuery = `SELECT ${config.tables.users.fields.id}, 
                               ${config.tables.users.fields.userId}, 
                               ${config.tables.users.fields.phoneNumber}, 
                               ${config.tables.users.fields.type}, 
                               ${config.tables.users.fields.authorizedRegion}, 
                               ${config.tables.users.fields.nickName}, 
                               jiandaoyun_record_id 
                        FROM ${config.tables.users.name}`;

      // 如果是增量同步，查询未同步的数据以及有收藏产品的用户
      if (config.sync.incremental) {
        usersQuery += ` WHERE ${config.sync.statusField} = ${config.sync.unsyncedValue} 
                      OR EXISTS (SELECT 1 FROM ${config.tables.favorites.name} 
                                 WHERE ${config.tables.favorites.fields.userPhone} = ${config.tables.users.fields.phoneNumber})`;
        console.log('启用增量同步模式，查询未同步数据及有收藏产品的用户');
      } else {
        console.log('启用全量同步模式，查询所有数据');
      }

      // 添加DISTINCT确保只返回唯一的用户数据
      usersQuery = usersQuery.replace('SELECT', 'SELECT DISTINCT');

      console.log('执行用户查询:', usersQuery);
      const [users] = await this.connection.execute(usersQuery);
      console.log(`查询结果: 共找到 ${users.length} 条需要同步的用户数据`);

      const syncData = [];

      // 为每个用户查询关联数据
      for (const user of users) {
        const userId = user[config.tables.users.fields.userId];
        const phoneNumber = user[config.tables.users.fields.phoneNumber];
        const jiandaoyunRecordId = user.jiandaoyun_record_id;

        // 查询负责人信息（usermanagements表）
        const [userManagements] = await this.connection.execute(
          `SELECT ${config.tables.userManagements.fields.userName} 
           FROM ${config.tables.userManagements.name} 
           WHERE ${config.tables.userManagements.fields.userId} = ?`,
          [userId]
        );

        // 查询用户收藏的产品（favorites表）
        const [favorites] = await this.connection.execute(
          `SELECT ${config.tables.favorites.fields.productId} 
           FROM ${config.tables.favorites.name} 
           WHERE ${config.tables.favorites.fields.userPhone} = ?`,
          [phoneNumber]
        );

        // 查询产品详情（products表）
        let products = [];
        if (favorites.length > 0) {
          const productIds = favorites.map(fav => fav[config.tables.favorites.fields.productId]);
          // 构建动态占位符字符串，用于处理IN查询的数组参数
          const placeholders = productIds.map(() => '?').join(',');
          const [productsResult] = await this.connection.execute(
            `SELECT ${config.tables.products.fields.productName}, 
                    ${config.tables.products.fields.specification}, 
                    ${config.tables.products.fields.quantity}, 
                    ${config.tables.products.fields.grossWeight}, 
                    ${config.tables.products.fields.yolk} 
             FROM ${config.tables.products.name} 
             WHERE ${config.tables.products.fields.productId} IN (${placeholders})`,
            productIds
          );
          products = productsResult;

          // 如果用户有收藏商品，无论当前同步状态如何，都将其重置为未同步状态
          // 这样可以确保有新收藏商品的用户数据会被重新同步到简道云
          await this.connection.execute(
            `UPDATE ${config.tables.users.name} 
             SET ${config.sync.statusField} = ? 
             WHERE ${config.tables.users.fields.userId} = ?`,
            [config.sync.unsyncedValue, userId]
          );
          console.log(`用户 ${userId} 有收藏商品，同步状态已重置为未同步`);
        }

        syncData.push({
          user,
          userManagement: userManagements[0] || {},
          products,
          userId: userId // 保存用户ID，用于同步后更新状态
        });
      }

      return syncData;
    } catch (error) {
      console.error('查询数据失败:', error.message);
      throw error;
    }
  }

  // 获取一条测试数据用于API测试
  async getTestData() {
    try {
      // 获取一条用户数据
      const [users] = await this.connection.execute(
        `SELECT ${config.tables.users.fields.id}, 
                ${config.tables.users.fields.userId}, 
                ${config.tables.users.fields.company}, 
                ${config.tables.users.fields.name}, 
                ${config.tables.users.fields.phoneNumber}, 
                ${config.tables.users.fields.type}, 
                ${config.tables.users.fields.city} 
         FROM ${config.tables.users.name} LIMIT 1`
      );

      if (users.length === 0) {
        console.error('没有找到用户数据');
        return null;
      }

      const user = users[0];
      const userId = user[config.tables.users.fields.id];

      // 获取该用户的购物车数据
      const [cartItems] = await this.connection.execute(
        `SELECT ${config.tables.cartItems.fields.productName}, 
                ${config.tables.cartItems.fields.specification}, 
                ${config.tables.cartItems.fields.quantity}, 
                ${config.tables.cartItems.fields.yolk} 
         FROM ${config.tables.cartItems.name} 
         WHERE ${config.tables.cartItems.fields.userId} = ?`,
        [userId]
      );

      // 获取该用户的产品数据
      const [products] = await this.connection.execute(
        `SELECT ${config.tables.products.fields.productName}, 
                ${config.tables.products.fields.specification}, 
                ${config.tables.products.fields.quantity}, 
                ${config.tables.products.fields.yolk} 
         FROM ${config.tables.products.name} 
         WHERE ${config.tables.products.fields.sellerId} = ?`,
        [userId]
      );

      return {
        user,
        cartItems,
        products
      };
    } catch (error) {
      console.error('获取测试数据失败:', error.message);
      throw error;
    }
  }

  // 更新数据同步状态
  async updateSyncStatus(userId, synced) {
    try {
      const statusValue = synced ? config.sync.syncedValue : config.sync.unsyncedValue;
      const now = new Date();

      await this.connection.execute(
        `UPDATE ${config.tables.users.name} 
         SET ${config.sync.statusField} = ?, ${config.sync.timeField} = ? 
         WHERE ${config.tables.users.fields.userId} = ?`,
        [statusValue, now, userId]
      );

      console.log(`用户 ${userId} 的同步状态已更新为: ${synced ? '已同步' : '未同步'}`);
    } catch (error) {
      console.error(`更新用户 ${userId} 同步状态失败:`, error.message);
      throw error;
    }
  }

  // 测试数据库连接和表结构
  async testDatabaseConnection() {
    try {
      // 测试连接
      await this.connect();

      // 查询表结构
      const tables = [config.tables.users.name, config.tables.cartItems.name, config.tables.products.name];

      for (const table of tables) {
        console.log(`\n--- 表 ${table} 结构 ---`);
        const [columns] = await this.connection.execute(`DESCRIBE ${table}`);
        columns.forEach(column => {
          console.log(`${column.Field}: ${column.Type} ${column.Null === 'YES' ? '(允许为空)' : '(不允许为空)'} ${column.Key === 'PRI' ? '(主键)' : ''}`);
        });
      }

      // 查询示例数据
      console.log(`\n--- 示例数据 ---`);
      const [usersSample] = await this.connection.execute(`SELECT * FROM ${config.tables.users.name} LIMIT 1`);
      if (usersSample.length > 0) {
        console.log('用户表示例数据:', usersSample[0]);

        const userId = usersSample[0][config.tables.users.fields.id];
        const [cartItemsSample] = await this.connection.execute(
          `SELECT * FROM ${config.tables.cartItems.name} WHERE ${config.tables.cartItems.fields.userId} = ? LIMIT 1`,
          [userId]
        );
        if (cartItemsSample.length > 0) {
          console.log('购物车表示例数据:', cartItemsSample[0]);
        }

        const [productsSample] = await this.connection.execute(
          `SELECT * FROM ${config.tables.products.name} WHERE ${config.tables.products.fields.sellerId} = ? LIMIT 1`,
          [userId]
        );
        if (productsSample.length > 0) {
          console.log('产品表示例数据:', productsSample[0]);
        }
      }

      await this.disconnect();
      return true;
    } catch (error) {
      console.error('数据库测试失败:', error.message);
      if (this.connection) {
        await this.disconnect();
      }
      return false;
    }
  }
}

module.exports = new DatabaseService();