const jwt = require('jsonwebtoken');
const logger = require('../utils/logger');
const redis = require('../config/redis');
const database = require('../config/database');

const socketHandler = (io) => {
  // Authentication middleware for Socket.IO
  io.use(async (socket, next) => {
    try {
      const token = socket.handshake.auth.token || socket.handshake.headers.authorization;
      
      if (!token) {
        return next(new Error('Authentication error: No token provided'));
      }

      const cleanToken = token.replace('Bearer ', '');
      const decoded = jwt.verify(cleanToken, process.env.JWT_SECRET);
      
      // Verify user session
      const session = await redis.getUserSession(decoded.id);
      if (!session) {
        return next(new Error('Authentication error: Session expired'));
      }

      // Get user info
      const [users] = await database.query(
        'SELECT id, username, email, role FROM users WHERE id = ? AND status = "active"',
        [decoded.id]
      );

      if (users.length === 0) {
        return next(new Error('Authentication error: User not found'));
      }

      socket.user = users[0];
      next();
    } catch (error) {
      logger.error('Socket authentication failed:', error);
      next(new Error('Authentication error: Invalid token'));
    }
  });

  io.on('connection', (socket) => {
    logger.info(`User connected: ${socket.user.username} (${socket.id})`);

    // Join user to their personal room
    socket.join(`user:${socket.user.id}`);
    
    // Join admin users to admin room
    if (socket.user.role === 'admin') {
      socket.join('admin');
    }

    // Handle device data updates
    socket.on('subscribe_device', (deviceId) => {
      socket.join(`device:${deviceId}`);
      logger.info(`User ${socket.user.username} subscribed to device ${deviceId}`);
    });

    socket.on('unsubscribe_device', (deviceId) => {
      socket.leave(`device:${deviceId}`);
      logger.info(`User ${socket.user.username} unsubscribed from device ${deviceId}`);
    });

    // Handle alert subscriptions
    socket.on('subscribe_alerts', () => {
      socket.join('alerts');
      logger.info(`User ${socket.user.username} subscribed to alerts`);
    });

    socket.on('unsubscribe_alerts', () => {
      socket.leave('alerts');
      logger.info(`User ${socket.user.username} unsubscribed from alerts`);
    });

    // Handle disconnect
    socket.on('disconnect', () => {
      logger.info(`User disconnected: ${socket.user.username} (${socket.id})`);
    });
  });

  // Export socket functions for use in other modules
  return {
    // Emit device data updates
    emitDeviceData: (deviceId, data) => {
      io.to(`device:${deviceId}`).emit('device_data_update', {
        deviceId,
        data,
        timestamp: new Date().toISOString()
      });
    },

    // Emit alerts
    emitAlert: (alert) => {
      io.to('alerts').emit('new_alert', {
        ...alert,
        timestamp: new Date().toISOString()
      });
    },

    // Emit to admin users
    emitToAdmin: (event, data) => {
      io.to('admin').emit(event, {
        ...data,
        timestamp: new Date().toISOString()
      });
    }
  };
};

module.exports = socketHandler;