jpeg roomcams first pass

server/src/services/roomCameraSnapshotService.js

@@ -0,0 +1,99 @@
+const EventEmitter = require('events');
+const logger = require('../globals/logger').child('roomCameraSnapshot');
+const { getRoomCameras, roomCameraEvents } = require('./roomCameraService');
+
+const POLL_INTERVAL_MS = 250; // 4 fps target
+const FETCH_TIMEOUT_MS = 2000;
+const STALE_AFTER_MS = 4000;
+
+const cameraState = new Map(); // id -> {frame, ts, stale, error, failures, fetching}
+const pollers = new Map();
+const events = new EventEmitter(); // frame, status
+
+function markState(id, updates = {}) {
+  const prev = cameraState.get(id) || {};
+  const next = { ...prev, ...updates };
+  if (next.ts != null) {
+    next.stale = Date.now() - next.ts > STALE_AFTER_MS || !!next.stale;
+  } else {
+    next.stale = true;
+  }
+  cameraState.set(id, next);
+  return next;
+}
+
+async function fetchSnapshot(camera) {
+  const { id, url } = camera;
+  const state = cameraState.get(id);
+  if (!url || state?.fetching) return;
+  markState(id, { fetching: true });
+  const abortController = new AbortController();
+  const timeout = setTimeout(() => abortController.abort(), FETCH_TIMEOUT_MS);
+  try {
+    const res = await fetch(url, { signal: abortController.signal });
+    if (!res.ok) {
+      throw new Error(`HTTP ${res.status}`);
+    }
+    const arrayBuffer = await res.arrayBuffer();
+    const buffer = Buffer.from(arrayBuffer);
+    const ts = Date.now();
+    const next = markState(id, { frame: buffer, ts, error: null, failures: 0 });
+    events.emit('frame', { id, buffer, ts, stale: !!next.stale });
+  } catch (err) {
+    const failures = (state?.failures || 0) + 1;
+    markState(id, { error: err.message, failures });
+    events.emit('status', { id, error: err.message });
+    logger.debug('Snapshot fetch failed', { id, err: err.message });
+  } finally {
+    clearTimeout(timeout);
+    markState(id, { fetching: false });
+  }
+}
+
+function startCamera(camera) {
+  const { id, url } = camera;
+  if (!url) {
+    logger.warn('Skipping room camera without URL', { id });
+    return;
+  }
+  if (pollers.has(id)) return;
+  markState(id, { frame: null, ts: null, error: null, failures: 0, fetching: false });
+  const poller = setInterval(() => fetchSnapshot(camera), POLL_INTERVAL_MS);
+  pollers.set(id, poller);
+  logger.info('Started snapshot polling', { id, url });
+}
+
+function stopAll() {
+  pollers.forEach((poller) => clearInterval(poller));
+  pollers.clear();
+  cameraState.clear();
+}
+
+function startAll() {
+  stopAll();
+  getRoomCameras().forEach((camera) => startCamera(camera));
+}
+
+function getState(id) {
+  const state = cameraState.get(id);
+  if (!state) return null;
+  const stale = state.ts == null || Date.now() - state.ts > STALE_AFTER_MS;
+  return {
+    frame: state.frame || null,
+    ts: state.ts || null,
+    stale,
+    error: state.error || null,
+  };
+}
+
+roomCameraEvents.on('update', () => {
+  logger.info('Room cameras changed; restarting snapshot pollers');
+  startAll();
+});
+
+startAll();
+
+module.exports = {
+  roomCameraStreamEvents: events,
+  getRoomCameraState: getState,
+};