// ─────────────────────────────────────────────────────────────
// Server Entry Point — Express + Socket.io
// ─────────────────────────────────────────────────────────────

import express from 'express';
import { createServer } from 'http';
import cors from 'cors';
import helmet from 'helmet';
import morgan from 'morgan';
import { Server } from 'socket.io';
import dotenv from 'dotenv';

dotenv.config();

const app = express();
const httpServer = createServer(app);

const PORT = process.env.PORT || 4000;
const CLIENT_URL = process.env.CLIENT_URL || 'http://localhost:3000';

// ─── Middleware ──────────────────────────────────────────────
app.use(helmet({ contentSecurityPolicy: false }));
app.use(cors({ origin: [CLIENT_URL, 'http://localhost:3000'], credentials: true }));
app.use(morgan('dev'));
app.use(express.json({ limit: '5mb' }));

// ─── Socket.io ───────────────────────────────────────────────
const io = new Server(httpServer, {
  cors: {
    origin: [CLIENT_URL, 'http://localhost:3000'],
    methods: ['GET', 'POST'],
    credentials: true,
  },
  transports: ['websocket', 'polling'],
  pingTimeout: 20000,
  pingInterval: 10000,
  maxHttpBufferSize: 1e6,
});

// Socket authentication middleware
io.use((socket, next) => {
  const token = socket.handshake.auth?.token;
  if (!token) return next(new Error('Authentication required'));
  // In production: verify JWT here
  // const payload = verifyAccessToken(token);
  (socket as any).userId = 'user-' + Math.random().toString(36).substr(2, 9);
  (socket as any).userName = 'User';
  (socket as any).userColor = '#4ECDC4';
  (socket as any).currentRoom = null;
  next();
});

// Socket connection handler
io.on('connection', (socket) => {
  console.log(`Client connected: ${socket.id}`);

  // ─── Room Handlers ────────────────────────────────────────
  socket.on('room:join', ({ roomId }) => {
    socket.join(roomId);
    (socket as any).currentRoom = roomId;
    
    socket.emit('room:joined', {
      room: { id: roomId, name: 'Demo Room', language: 'javascript' },
      members: [],
      files: [{ id: 'file-1', roomId, name: 'main.js', path: '/main.js', content: '// Start coding!\\n', language: 'javascript', createdAt: new Date().toISOString(), updatedAt: new Date().toISOString() }],
    });
    
    socket.to(roomId).emit('room:member-joined', {
      userId: (socket as any).userId,
      userName: (socket as any).userName,
    });
  });

  socket.on('room:leave', () => {
    const roomId = (socket as any).currentRoom;
    if (roomId) {
      socket.leave(roomId);
      socket.to(roomId).emit('room:member-left', { userId: (socket as any).userId });
      (socket as any).currentRoom = null;
    }
  });

  // ─── Document Sync (CRDT) ─────────────────────────────────
  socket.on('doc:update', (data) => {
    const roomId = (socket as any).currentRoom;
    if (roomId) {
      socket.to(roomId).emit('doc:sync', data);
    }
  });

  socket.on('doc:request-state', (data) => {
    socket.emit('doc:state', { state: [], fileId: data.fileId });
  });

  // ─── Cursor & Presence ────────────────────────────────────
  socket.on('cursor:move', (data) => {
    const roomId = (socket as any).currentRoom;
    if (roomId) {
      socket.to(roomId).emit('cursor:update', [{
        userId: (socket as any).userId,
        userName: (socket as any).userName,
        userColor: (socket as any).userColor,
        ...data,
      }]);
    }
  });

  // ─── Chat ─────────────────────────────────────────────────
  socket.on('chat:send', (data) => {
    const roomId = (socket as any).currentRoom;
    if (roomId) {
      const message = {
        id: Date.now().toString(),
        content: data.content,
        userId: (socket as any).userId,
        userName: (socket as any).userName,
        userAvatar: null,
        roomId,
        type: data.type || 'text',
        createdAt: new Date().toISOString(),
      };
      io.to(roomId).emit('chat:message', message);
    }
  });

  socket.on('chat:typing', (data) => {
    const roomId = (socket as any).currentRoom;
    if (roomId) {
      socket.to(roomId).emit('chat:typing', {
        userId: (socket as any).userId,
        userName: (socket as any).userName,
        isTyping: data.isTyping,
      });
    }
  });

  socket.on('chat:history', () => {
    socket.emit('chat:history', []);
  });

  // ─── Code Execution ───────────────────────────────────────
  socket.on('exec:run', async (data) => {
    const roomId = (socket as any).currentRoom;
    socket.emit('exec:output', { id: 'exec-1', chunk: `[Running ${data.language}...]\\n`, stream: 'stdout' });
    
    // Simulated execution — in production uses Docker
    setTimeout(() => {
      socket.emit('exec:output', { id: 'exec-1', chunk: 'Hello, World!\\n', stream: 'stdout' });
      if (roomId) {
        io.to(roomId).emit('exec:complete', {
          id: 'exec-1',
          stdout: 'Hello, World!\\n',
          stderr: '',
          exitCode: 0,
          duration: 42,
          memoryUsed: 1024,
          timedOut: false,
        });
      }
    }, 500);
  });

  // ─── WebRTC Signaling ─────────────────────────────────────
  socket.on('webrtc:join', () => {
    const roomId = (socket as any).currentRoom;
    if (roomId) {
      socket.to(roomId).emit('webrtc:peer-joined', {
        peerId: socket.id,
        peerName: (socket as any).userName,
      });
    }
  });

  socket.on('webrtc:offer', (data) => {
    const target = io.sockets.sockets.get(data.to);
    if (target) {
      target.emit('webrtc:offer', { ...data, from: socket.id });
    }
  });

  socket.on('webrtc:answer', (data) => {
    const target = io.sockets.sockets.get(data.to);
    if (target) {
      target.emit('webrtc:answer', { ...data, from: socket.id });
    }
  });

  socket.on('webrtc:ice-candidate', (data) => {
    const target = io.sockets.sockets.get(data.to);
    if (target) {
      target.emit('webrtc:ice-candidate', { ...data, from: socket.id });
    }
  });

  // ─── Disconnect ───────────────────────────────────────────
  socket.on('disconnect', () => {
    const roomId = (socket as any).currentRoom;
    if (roomId) {
      socket.to(roomId).emit('room:member-left', { userId: (socket as any).userId });
      socket.to(roomId).emit('webrtc:peer-left', { peerId: socket.id });
    }
    console.log(`Client disconnected: ${socket.id}`);
  });
});

// ─── REST API Routes ─────────────────────────────────────────

app.get('/api/health', (_req, res) => {
  res.json({ status: 'healthy', timestamp: new Date().toISOString(), version: '1.0.0' });
});

// Auth routes (simplified for demo — full implementation in services/)
app.post('/api/auth/register', (req, res) => {
  const { email, name } = req.body;
  const user = { id: 'user-' + Math.random().toString(36).substr(2, 9), email, name, avatar: null, provider: 'local', createdAt: new Date().toISOString() };
  const tokens = { accessToken: 'demo-token-' + user.id, refreshToken: 'refresh-' + user.id };
  res.status(201).json({ success: true, data: { user, tokens } });
});

app.post('/api/auth/login', (req, res) => {
  const { email } = req.body;
  const user = { id: 'user-' + Math.random().toString(36).substr(2, 9), email, name: email.split('@')[0], avatar: null, provider: 'local', createdAt: new Date().toISOString() };
  const tokens = { accessToken: 'demo-token-' + user.id, refreshToken: 'refresh-' + user.id };
  res.json({ success: true, data: { user, tokens } });
});

app.get('/api/rooms', (_req, res) => {
  res.json({ success: true, data: [] });
});

app.post('/api/rooms', (req, res) => {
  const { name, language, isPublic } = req.body;
  const room = {
    id: 'room-' + Math.random().toString(36).substr(2, 9),
    name, language, isPublic,
    ownerId: 'user-1',
    inviteCode: Math.random().toString(36).substr(2, 8),
    maxMembers: 10,
    createdAt: new Date().toISOString(),
    updatedAt: new Date().toISOString(),
  };
  res.status(201).json({ success: true, data: room });
});

app.post('/api/ai/action', (req, res) => {
  res.json({ success: true, data: { content: 'AI service requires OPENROUTER_API_KEY configuration.', suggestions: [] } });
});

app.get('/api/snippets', (_req, res) => {
  res.json({ success: true, data: [] });
});

// ─── Error Handler ───────────────────────────────────────────
app.use((_req, res) => {
  res.status(404).json({ success: false, error: { code: 'NOT_FOUND', message: 'Endpoint not found' } });
});

// ─── Start Server ────────────────────────────────────────────
httpServer.listen(PORT, () => {
  console.log(`
  ╔══════════════════════════════════════════════════╗
  ║       CodeSync Server Running                   ║
  ╠══════════════════════════════════════════════════╣
  ║  HTTP:      http://localhost:${PORT}              ║
  ║  WebSocket: ws://localhost:${PORT}                ║
  ╚══════════════════════════════════════════════════╝
  `);
});

export { app, httpServer, io };