const jwt = require('jsonwebtoken');
const dbConnector = require('../utils/dbConnector');

const JWT_SECRET = process.env.JWT_SECRET || 'your-secret-key';

/**
 * JWT认证中间件
 * 验证token并附加用户信息到req对象
 */
const authMiddleware = async (req, res, next) => {
  try {
    const authHeader = req.headers.authorization;
    
    if (!authHeader || !authHeader.startsWith('Bearer ')) {
      return res.status(401).json({
        code: 401,
        message: '未提供有效的认证token',
        data: null
      });
    }

    const token = authHeader.substring(7); // 移除'Bearer '前缀

    try {
      // 验证token
      const decoded = jwt.verify(token, JWT_SECRET);
      
      // 查询用户信息
      const users = await dbConnector.query(
        'SELECT id, username, phone, email, user_type, avatar_url, status FROM users WHERE id = ?',
        [decoded.userId]
      );

      if (users.length === 0) {
        return res.status(401).json({
          code: 401,
          message: '用户不存在',
          data: null
        });
      }

      const user = users[0];

      // 检查用户状态
      if (user.status !== 1) {
        return res.status(401).json({
          code: 401,
          message: '用户已被禁用',
          data: null
        });
      }

      // 附加用户信息到请求对象
      req.user = {
        id: user.id,
        username: user.username,
        phone: user.phone,
        email: user.email,
        user_type: user.user_type,
        avatar_url: user.avatar_url
      };

      next();

    } catch (jwtError) {
      if (jwtError.name === 'TokenExpiredError') {
        return res.status(401).json({
          code: 401,
          message: 'token已过期',
          data: null
        });
      }
      
      if (jwtError.name === 'JsonWebTokenError') {
        return res.status(401).json({
          code: 401,
          message: '无效的token',
          data: null
        });
      }

      throw jwtError;
    }

  } catch (error) {
    console.error('认证中间件错误:', error);
    return res.status(500).json({
      code: 500,
      message: '服务器内部错误',
      data: null
    });
  }
};

/**
 * 可选认证中间件
 * 如果提供了token就验证，不提供也不报错
 */
const optionalAuth = async (req, res, next) => {
  try {
    const authHeader = req.headers.authorization;
    
    if (authHeader && authHeader.startsWith('Bearer ')) {
      const token = authHeader.substring(7);
      
      try {
        const decoded = jwt.verify(token, JWT_SECRET);
        
        const users = await dbConnector.query(
          'SELECT id, username, phone, email, user_type, avatar_url, status FROM users WHERE id = ? AND status = 1',
          [decoded.userId]
        );

        if (users.length > 0) {
          const user = users[0];
          req.user = {
            id: user.id,
            username: user.username,
            phone: user.phone,
            email: user.email,
            user_type: user.user_type,
            avatar_url: user.avatar_url
          };
        }
      } catch (error) {
        // token无效，但不阻止请求继续
        console.warn('可选认证失败:', error.message);
      }
    }

    next();
  } catch (error) {
    console.error('可选认证中间件错误:', error);
    next();
  }
};

/**
 * 管理员权限检查中间件
 */
const adminRequired = (req, res, next) => {
  if (!req.user) {
    return res.status(401).json({
      code: 401,
      message: '需要登录',
      data: null
    });
  }

  if (req.user.user_type !== 'admin') {
    return res.status(403).json({
      code: 403,
      message: '需要管理员权限',
      data: null
    });
  }

  next();
};

module.exports = {
  authMiddleware,
  optionalAuth,
  adminRequired
};