programmierhub/server.js

'use strict';
/*
 * VR ProgrammierHub — Backend-Grundgeruest (Phase 1)
 * Ein einziger Node-Prozess: liefert die Frontend-Assets aus UND haelt den
 * Echtzeit-Raumzustand (WebSocket-Hub, komplett im RAM).
 *
 * Protokoll siehe Spezifikation Abschnitt 9.2. Auth (Login/Rollen) folgt als
 * naechster Schritt — hier zunaechst Name + Rolle aus dem "hello"-Frame.
 */
const express = require('express');
const http = require('http');
const path = require('path');
const { WebSocketServer } = require('ws');

const PORT = process.env.PORT || 3000;

// ── HTTP: statische Assets ──────────────────────────────────────────────
const app = express();
app.use(express.static(path.join(__dirname, 'public'), { extensions: ['html'] }));
app.get('/health', (_req, res) => res.json({ ok: true, users: clients.size, uptime: process.uptime() }));

const server = http.createServer(app);

// ── Realtime-Hub: fluechtiger Raumzustand im Arbeitsspeicher ────────────
const wss = new WebSocketServer({ server, path: '/ws' });
let nextId = 1;
/** id -> { ws, alive, state } */
const clients = new Map();

function send(ws, obj) { if (ws.readyState === 1) ws.send(JSON.stringify(obj)); }
function broadcast(obj, exceptId) {
  const msg = JSON.stringify(obj);
  for (const [id, c] of clients) if (id !== exceptId && c.ws.readyState === 1) c.ws.send(msg);
}

wss.on('connection', (ws) => {
  const id = nextId++;
  const state = { id, name: '…', role: 'student', p: [0, 0, 8], rot: 0, anim: 'idle', label: '', help: false };
  const client = { ws, alive: true, state, joined: false };
  clients.set(id, client);
  ws.on('pong', () => (client.alive = true));

  ws.on('message', (data) => {
    let m;
    try { m = JSON.parse(data); } catch { return; }
    switch (m.t) {
      case 'hello': {
        state.name = String(m.name || 'Gast').slice(0, 24) || 'Gast';
        state.role = m.role === 'teacher' ? 'teacher' : 'student';
        if (Array.isArray(m.p) && m.p.length === 3) state.p = m.p.map(Number);
        // eigene id + Vollzustand aller anderen an den neuen Client
        send(ws, { t: 'welcome', id, users: [...clients.values()].filter((c) => c.state.id !== id).map((c) => c.state) });
        client.joined = true;
        broadcast({ t: 'join', user: state }, id); // andere ueber Neuzugang informieren
        break;
      }
      case 'move': {
        if (!client.joined) break;
        if (Array.isArray(m.p) && m.p.length === 3) state.p = m.p.map(Number);
        if (typeof m.rot === 'number') state.rot = m.rot;
        if (typeof m.anim === 'string') state.anim = m.anim;
        broadcast({ t: 'update', id, p: state.p, rot: state.rot, anim: state.anim }, id);
        break;
      }
      case 'status': {
        state.label = String(m.label || '').slice(0, 40);
        broadcast({ t: 'status', id, label: state.label }, id);
        break;
      }
      case 'help': {
        state.help = !!m.on;
        broadcast({ t: 'help', id, on: state.help }, id);
        break;
      }
    }
  });

  ws.on('close', () => { clients.delete(id); broadcast({ t: 'leave', id }); });
  ws.on('error', () => {});
});

// ── Heartbeat: tote Verbindungen aufraeumen ─────────────────────────────
setInterval(() => {
  for (const [id, c] of clients) {
    if (!c.alive) { try { c.ws.terminate(); } catch {} clients.delete(id); broadcast({ t: 'leave', id }); continue; }
    c.alive = false;
    try { c.ws.ping(); } catch {}
  }
}, 15000);

server.listen(PORT, () => console.log(`[ProgrammierHub] laeuft auf :${PORT}  (WS-Pfad /ws)`));