// Sri AI Live Class - signaling + auth server
// Multi-room conference: every participant can publish cam/mic/screen; teacher = host
const express = require('express');
const http = require('http');
const path = require('path');
const { WebSocketServer } = require('ws');

const PORT = process.env.PORT || 3010;

// ---- Dummy accounts (replace with srigen auth on migration) ----
const USERS = {
  'teacher@sriai.lk':  { password: 'teach123', role: 'teacher', name: 'Ms. Nova' },
  'teacher2@sriai.lk': { password: 'teach123', role: 'teacher', name: 'Mr. Silva' },
  'student1@sriai.lk': { password: 'stud123',  role: 'student', name: 'Aisha' },
  'student2@sriai.lk': { password: 'stud123',  role: 'student', name: 'Kasun' },
  'student3@sriai.lk': { password: 'stud123',  role: 'student', name: 'Tharushi' },
};

const app = express();
app.use(express.json());
app.use(express.static(path.join(__dirname, 'public')));

app.post('/login', (req, res) => {
  const { email, password } = req.body || {};
  const u = USERS[(email || '').toLowerCase().trim()];
  if (!u || u.password !== password) {
    return res.status(401).json({ ok: false, error: 'Invalid email or password' });
  }
  res.json({ ok: true, role: u.role, name: u.name, email });
});

const server = http.createServer(app);
const wss = new WebSocketServer({ server });

let nextId = 1;
const clients = new Map(); // id -> { ws, role, name, roomId }
const rooms = new Map();   // roomId -> { id, name, teacherId, teacherName, chat: [] }

function send(id, msg) {
  const c = clients.get(id);
  if (c && c.ws.readyState === 1) c.ws.send(JSON.stringify(msg));
}
function roomMembers(roomId) {
  return [...clients.entries()].filter(([, c]) => c.roomId === roomId);
}
function roomBroadcast(roomId, msg, exceptId = null) {
  for (const [id] of roomMembers(roomId)) if (id !== exceptId) send(id, msg);
}
function classList() {
  return [...rooms.values()].map(r => ({
    id: r.id, name: r.name, teacher: r.teacherName,
    students: roomMembers(r.id).filter(([, c]) => c.role === 'student').length,
  }));
}
function broadcastClassList() {
  const msg = { type: 'class-list', classes: classList() };
  for (const [id, c] of clients) {
    if (c.role === 'student' && !c.roomId) send(id, msg);
  }
}
function endRoom(roomId, reason) {
  const room = rooms.get(roomId);
  if (!room) return;
  for (const [mid, mc] of roomMembers(roomId)) {
    if (mid === room.teacherId) continue;
    mc.roomId = null;
    send(mid, { type: 'class-ended', reason });
  }
  rooms.delete(roomId); // chat history dies with the room
  broadcastClassList();
}
function teacherRoom(teacherId) {
  return [...rooms.values()].find(r => r.teacherId === teacherId);
}

wss.on('connection', (ws) => {
  const id = nextId++;
  let joined = false;

  ws.on('message', (raw) => {
    let msg;
    try { msg = JSON.parse(raw); } catch { return; }

    if (msg.type === 'hello') {
      clients.set(id, { ws, role: msg.role, name: msg.name, roomId: null });
      joined = true;
      send(id, { type: 'welcome', id });
      if (msg.role === 'student') send(id, { type: 'class-list', classes: classList() });
      return;
    }
    if (!joined) return;
    const c = clients.get(id);

    switch (msg.type) {
      // WebRTC signaling relay (perfect-negotiation payloads)
      case 'signal': {
        const target = clients.get(msg.to);
        if (target && target.roomId && target.roomId === c.roomId) {
          send(msg.to, { type: 'signal', from: id, data: msg.data });
        }
        break;
      }
      // announce which of my stream ids is camera vs screen
      case 'meta':
        if (c.roomId) roomBroadcast(c.roomId, { type: 'meta', from: id, cam: msg.cam || null, screen: msg.screen || null }, id);
        break;
      // mic/cam/sharing status for UI icons
      case 'state':
        if (c.roomId) roomBroadcast(c.roomId, { type: 'state', from: id, mic: !!msg.mic, cam: !!msg.cam, sharing: !!msg.sharing }, id);
        break;

      case 'chat': {
        if (!c.roomId) break;
        const room = rooms.get(c.roomId);
        const text = String(msg.text || '').slice(0, 500).trim();
        if (!room || !text) break;
        const entry = { from: id, name: c.name, role: c.role, text, ts: Date.now() };
        room.chat.push(entry);
        if (room.chat.length > 300) room.chat.shift();
        roomBroadcast(c.roomId, { type: 'chat', ...entry });
        break;
      }

      // host (teacher) mutes a student's mic or turns off their camera
      case 'host-control': {
        const room = teacherRoom(id);
        const target = clients.get(msg.to);
        if (room && target && target.roomId === room.id && ['mute-mic', 'stop-cam'].includes(msg.action)) {
          send(msg.to, { type: 'host-control', action: msg.action });
        }
        break;
      }

      // ---- teacher ----
      case 'create-class': {
        if (c.role !== 'teacher') break;
        const existing = teacherRoom(id);
        if (existing) endRoom(existing.id, 'Teacher started a new class');
        const roomId = 'r' + id + '-' + nextId++;
        const name = String(msg.name || '').slice(0, 60).trim() || `${c.name}'s Class`;
        rooms.set(roomId, { id: roomId, name, teacherId: id, teacherName: c.name, chat: [] });
        c.roomId = roomId;
        send(id, { type: 'class-created', roomId, name });
        broadcastClassList();
        break;
      }
      case 'end-class': {
        const room = teacherRoom(id);
        if (room) { endRoom(room.id, 'Class ended by teacher'); c.roomId = null; }
        break;
      }

      // ---- student ----
      case 'join-class': {
        if (c.role !== 'student') break;
        const room = rooms.get(msg.roomId);
        if (!room) { send(id, { type: 'class-list', classes: classList() }); break; }
        const participants = roomMembers(room.id).map(([mid, mc]) => ({ id: mid, name: mc.name, role: mc.role }));
        c.roomId = room.id;
        send(id, {
          type: 'joined', roomId: room.id, className: room.name,
          teacherName: room.teacherName, teacherId: room.teacherId,
          participants, chat: room.chat,
        });
        roomBroadcast(room.id, { type: 'peer-joined', id, name: c.name, role: c.role }, id);
        broadcastClassList();
        break;
      }
      case 'leave-class': {
        if (!c.roomId) break;
        const roomId = c.roomId;
        c.roomId = null;
        roomBroadcast(roomId, { type: 'peer-left', id });
        send(id, { type: 'class-list', classes: classList() });
        broadcastClassList();
        break;
      }
      case 'list-classes':
        send(id, { type: 'class-list', classes: classList() });
        break;
    }
  });

  ws.on('close', () => {
    if (!joined) return;
    const c = clients.get(id);
    clients.delete(id);
    if (!c) return;
    if (c.role === 'teacher') {
      const room = teacherRoom(id);
      if (room) endRoom(room.id, 'Teacher disconnected');
    } else if (c.roomId) {
      roomBroadcast(c.roomId, { type: 'peer-left', id });
      broadcastClassList();
    }
  });
});

server.listen(PORT, () => {
  console.log(`Sri AI Live Class running at http://localhost:${PORT}`);
});