'use strict';

const express = require('express');
const http    = require('http');
const path    = require('path');
const { createSnapshotRouter } = require('./src/snapshotService');

const PORT       = parseInt(process.env.PORT        ?? '8444', 10);
const GO2RTC_URL = process.env.GO2RTC_URL ?? 'http://localhost:1984';

const app = express();

app.use(express.static(path.join(__dirname, 'public')));
app.use('/api/snapshot', createSnapshotRouter(GO2RTC_URL));

// ── WebRTC signaling proxy ────────────────────────────────────────────────────
// Browser postet SDP-Offer hierher; wir leiten es an go2rtc weiter und
// geben die SDP-Answer zurück. Nur ein HTTP-Port nach aussen nötig.
app.post(
  '/api/webrtc',
  express.text({ type: 'application/sdp', limit: '64kb' }),
  async (req, res) => {
    const src = req.query.src ?? '';
    try {
      const upstream = await fetch(
        `${GO2RTC_URL}/api/webrtc?src=${encodeURIComponent(src)}`,
        {
          method:  'POST',
          headers: { 'Content-Type': 'application/sdp' },
          body:    req.body,
        }
      );
      if (!upstream.ok) {
        const msg = await upstream.text();
        return res.status(upstream.status).send(msg);
      }
      const answer = await upstream.text();
      res.set('Content-Type', 'application/sdp');
      res.send(answer);
    } catch (err) {
      res.status(503).json({ error: `go2rtc nicht erreichbar: ${err.message}` });
    }
  }
);

// ── Health ────────────────────────────────────────────────────────────────────
app.get('/health', async (_req, res) => {
  let go2rtcOk = false;
  try {
    const r = await fetch(`${GO2RTC_URL}/api/streams`);
    go2rtcOk = r.ok;
  } catch { /* not reachable */ }

  res.json({ status: go2rtcOk ? 'ok' : 'degraded', go2rtc: go2rtcOk });
});

// ── Start ─────────────────────────────────────────────────────────────────────
const server = http.createServer(app);

server.listen(PORT, '0.0.0.0', () => {
  console.log(`AppRobotWebcam on http://0.0.0.0:${PORT}`);
  console.log(`  go2rtc backend: ${GO2RTC_URL}`);
  console.log(`  WebRTC signaling proxy: POST /api/webrtc?src=cam0`);
  console.log(`  Snapshot API:           GET  /api/snapshot/cam0`);
});

const shutdown = (sig) => {
  console.log(`\n${sig} – shutting down`);
  server.close(() => process.exit(0));
};
process.on('SIGINT',  () => shutdown('SIGINT'));
process.on('SIGTERM', () => shutdown('SIGTERM'));