const { Server } = require('socket.io');
const { verifyToken } = require('../utils/auth');
const { prisma } = require('../utils/db');

// Track active users in each event room
const activeUsers = new Map(); // eventId -> Set of { socketId, userId, username, avatar }

// Global Socket.IO instance
let io;

function getIO() {
  if (!io) {
    throw new Error('Socket.IO not initialized');
  }
  return io;
}

function initializeSocket(httpServer) {
  io = new Server(httpServer, {
    cors: {
      origin: process.env.CORS_ORIGIN || 'http://localhost:8080',
      credentials: true,
    },
  });

  // Authentication middleware for Socket.IO
  io.use(async (socket, next) => {
    try {
      const token = socket.handshake.auth.token;

      if (!token) {
        return next(new Error('Authentication required'));
      }

      const decoded = verifyToken(token);
      if (!decoded) {
        return next(new Error('Invalid token'));
      }

      // Get user from database
      const user = await prisma.user.findUnique({
        where: { id: decoded.userId },
        select: {
          id: true,
          username: true,
          email: true,
          avatar: true,
        },
      });

      if (!user) {
        return next(new Error('User not found'));
      }

      socket.user = user;
      next();
    } catch (error) {
      console.error('Socket auth error:', error);
      next(new Error('Authentication failed'));
    }
  });

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

    // Join user's personal room for notifications
    const userRoom = `user_${socket.user.id}`;
    socket.join(userRoom);
    console.log(`📬 ${socket.user.username} joined personal room: ${userRoom}`);

    // Join event room
    socket.on('join_event_room', async ({ slug }) => {
      try {
        // Find event by slug
        const event = await prisma.event.findUnique({
          where: { slug },
          select: { id: true, slug: true },
        });

        if (!event) {
          socket.emit('error', { message: 'Event not found' });
          return;
        }

        const eventId = event.id;
        const roomName = `event_${eventId}`;

        // Verify that user has checked in to this event
        const participant = await prisma.eventParticipant.findUnique({
          where: {
            userId_eventId: {
              userId: socket.user.id,
              eventId: eventId,
            },
          },
        });

        if (!participant) {
          socket.emit('error', { message: 'You must check in to this event first' });
          return;
        }

        socket.join(roomName);
        socket.currentEventRoom = roomName;
        socket.currentEventId = eventId;
        socket.currentEventSlug = slug;

        // Add user to active users
        if (!activeUsers.has(eventId)) {
          activeUsers.set(eventId, new Set());
        }

        const userInfo = {
          socketId: socket.id,
          userId: socket.user.id,
          username: socket.user.username,
          avatar: socket.user.avatar,
        };

        activeUsers.get(eventId).add(JSON.stringify(userInfo));

        console.log(`👤 ${socket.user.username} joined event room ${slug} (ID: ${eventId})`);

        // Load last 20 messages from database
        const chatRoom = await prisma.chatRoom.findFirst({
          where: {
            eventId: parseInt(eventId),
            type: 'event',
          },
        });

        if (chatRoom) {
          const messages = await prisma.message.findMany({
            where: { roomId: chatRoom.id },
            include: {
              user: {
                select: {
                  id: true,
                  username: true,
                  avatar: true,
                },
              },
            },
            orderBy: { createdAt: 'desc' },
            take: 20,
          });

          // Send message history to the joining user (reverse to chronological order)
          socket.emit('message_history', messages.reverse().map(msg => ({
            id: msg.id,
            roomId: msg.roomId,
            userId: msg.user.id,
            username: msg.user.username,
            avatar: msg.user.avatar,
            content: msg.content,
            type: msg.type,
            createdAt: msg.createdAt,
          })));
        }

        // Broadcast updated active users list
        const users = Array.from(activeUsers.get(eventId)).map(u => JSON.parse(u));
        io.to(roomName).emit('active_users', users);

        // Notify room about new user
        socket.to(roomName).emit('user_joined', {
          userId: socket.user.id,
          username: socket.user.username,
          avatar: socket.user.avatar,
        });
      } catch (error) {
        console.error('Join event room error:', error);
        socket.emit('error', { message: 'Failed to join room' });
      }
    });

    // Leave event room
    socket.on('leave_event_room', () => {
      if (!socket.currentEventId || !socket.currentEventRoom) {
        return;
      }

      const eventId = socket.currentEventId;
      const roomName = socket.currentEventRoom;
      socket.leave(roomName);

      // Remove from active users
      if (activeUsers.has(eventId)) {
        const users = activeUsers.get(eventId);
        const userInfo = JSON.stringify({
          socketId: socket.id,
          userId: socket.user.id,
          username: socket.user.username,
          avatar: socket.user.avatar,
        });
        users.delete(userInfo);

        // Broadcast updated list
        const updatedUsers = Array.from(users).map(u => JSON.parse(u));
        io.to(roomName).emit('active_users', updatedUsers);
      }

      console.log(`👤 ${socket.user.username} left event room ${socket.currentEventSlug}`);

      // Clear current event data
      socket.currentEventId = null;
      socket.currentEventRoom = null;
      socket.currentEventSlug = null;
    });

    // Send message to event room
    socket.on('send_event_message', async ({ content }) => {
      try {
        if (!socket.currentEventId || !socket.currentEventRoom) {
          return socket.emit('error', { message: 'Not in an event room' });
        }

        const eventId = socket.currentEventId;
        const roomName = socket.currentEventRoom;

        // Save message to database
        const chatRoom = await prisma.chatRoom.findFirst({
          where: {
            eventId: eventId,
            type: 'event',
          },
        });

        if (!chatRoom) {
          return socket.emit('error', { message: 'Chat room not found' });
        }

        const message = await prisma.message.create({
          data: {
            roomId: chatRoom.id,
            userId: socket.user.id,
            content,
            type: 'text',
          },
          include: {
            user: {
              select: {
                id: true,
                username: true,
                avatar: true,
              },
            },
          },
        });

        // Broadcast message to room
        io.to(roomName).emit('event_message', {
          id: message.id,
          roomId: message.roomId,
          userId: message.user.id,
          username: message.user.username,
          avatar: message.user.avatar,
          content: message.content,
          type: message.type,
          createdAt: message.createdAt,
        });

        console.log(`💬 Message in event ${socket.currentEventSlug} from ${socket.user.username}`);
      } catch (error) {
        console.error('Send message error:', error);
        socket.emit('error', { message: 'Failed to send message' });
      }
    });

    // Join private match room
    socket.on('join_match_room', ({ matchId }) => {
      const roomName = `match_${matchId}`;
      socket.join(roomName);
      socket.currentMatchRoom = roomName;
      console.log(`👥 ${socket.user.username} joined match room ${matchId}`);
    });

    // Send message to match room
    socket.on('send_match_message', async ({ matchId, content }) => {
      try {
        const roomName = `match_${matchId}`;

        // Get match and its room
        const match = await prisma.match.findUnique({
          where: { id: parseInt(matchId) },
          include: { room: true },
        });

        if (!match || !match.room) {
          return socket.emit('error', { message: 'Match room not found' });
        }

        // Save message
        const message = await prisma.message.create({
          data: {
            roomId: match.room.id,
            userId: socket.user.id,
            content,
            type: 'text',
          },
          include: {
            user: {
              select: {
                id: true,
                username: true,
                avatar: true,
              },
            },
          },
        });

        // Broadcast to match room
        io.to(roomName).emit('match_message', {
          id: message.id,
          roomId: message.roomId,
          userId: message.user.id,
          username: message.user.username,
          avatar: message.user.avatar,
          content: message.content,
          type: message.type,
          createdAt: message.createdAt,
        });

        console.log(`💬 Private message in match ${matchId} from ${socket.user.username}`);
      } catch (error) {
        console.error('Send match message error:', error);
        socket.emit('error', { message: 'Failed to send message' });
      }
    });

    // WebRTC Signaling Events

    // Send WebRTC offer
    socket.on('webrtc_offer', async ({ matchId, offer }) => {
      try {
        const roomName = `match_${matchId}`;

        // Verify user is part of this match
        const match = await prisma.match.findUnique({
          where: { id: parseInt(matchId) },
          select: { user1Id: true, user2Id: true },
        });

        if (!match) {
          return socket.emit('error', { message: 'Match not found' });
        }

        if (match.user1Id !== socket.user.id && match.user2Id !== socket.user.id) {
          return socket.emit('error', { message: 'Not authorized for this match' });
        }

        // Forward offer to the other user in the match room
        socket.to(roomName).emit('webrtc_offer', {
          from: socket.user.id,
          offer,
        });

        console.log(`📡 WebRTC offer sent in match ${matchId} from ${socket.user.username}`);
      } catch (error) {
        console.error('WebRTC offer error:', error);
        socket.emit('error', { message: 'Failed to send WebRTC offer' });
      }
    });

    // Send WebRTC answer
    socket.on('webrtc_answer', async ({ matchId, answer }) => {
      try {
        const roomName = `match_${matchId}`;

        // Verify user is part of this match
        const match = await prisma.match.findUnique({
          where: { id: parseInt(matchId) },
          select: { user1Id: true, user2Id: true },
        });

        if (!match) {
          return socket.emit('error', { message: 'Match not found' });
        }

        if (match.user1Id !== socket.user.id && match.user2Id !== socket.user.id) {
          return socket.emit('error', { message: 'Not authorized for this match' });
        }

        // Forward answer to the other user in the match room
        socket.to(roomName).emit('webrtc_answer', {
          from: socket.user.id,
          answer,
        });

        console.log(`📡 WebRTC answer sent in match ${matchId} from ${socket.user.username}`);
      } catch (error) {
        console.error('WebRTC answer error:', error);
        socket.emit('error', { message: 'Failed to send WebRTC answer' });
      }
    });

    // Send ICE candidate
    socket.on('webrtc_ice_candidate', async ({ matchId, candidate }) => {
      try {
        const roomName = `match_${matchId}`;

        // Verify user is part of this match
        const match = await prisma.match.findUnique({
          where: { id: parseInt(matchId) },
          select: { user1Id: true, user2Id: true },
        });

        if (!match) {
          return socket.emit('error', { message: 'Match not found' });
        }

        if (match.user1Id !== socket.user.id && match.user2Id !== socket.user.id) {
          return socket.emit('error', { message: 'Not authorized for this match' });
        }

        // Forward ICE candidate to the other user in the match room
        socket.to(roomName).emit('webrtc_ice_candidate', {
          from: socket.user.id,
          candidate,
        });

        console.log(`🧊 ICE candidate sent in match ${matchId} from ${socket.user.username}`);
      } catch (error) {
        console.error('ICE candidate error:', error);
        socket.emit('error', { message: 'Failed to send ICE candidate' });
      }
    });

    // Handle disconnection
    socket.on('disconnect', () => {
      console.log(`❌ User disconnected: ${socket.user.username} (${socket.id})`);

      // Remove from active users in all event rooms
      if (socket.currentEventId) {
        const eventId = socket.currentEventId;
        if (activeUsers.has(eventId)) {
          const users = activeUsers.get(eventId);
          const userInfo = JSON.stringify({
            socketId: socket.id,
            userId: socket.user.id,
            username: socket.user.username,
            avatar: socket.user.avatar,
          });
          users.delete(userInfo);

          // Broadcast updated list
          const updatedUsers = Array.from(users).map(u => JSON.parse(u));
          io.to(socket.currentEventRoom).emit('active_users', updatedUsers);

          // Notify about user leaving
          socket.to(socket.currentEventRoom).emit('user_left', {
            userId: socket.user.id,
            username: socket.user.username,
          });
        }
      }
    });
  });

  console.log('🔌 Socket.IO initialized');
  return io;
}

module.exports = { initializeSocket, getIO };