room camera and rover snapshots

server/src/services/roomCameraService/socketGateway.js

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+// Room Camera Socket Gateway
+// Purpose: Manages room-camera subscription sockets and forwards frame/status events to authorized viewers.
+// Scope: Owns socket-level auth checks, subscription state, throttling, and event fan-out.
+const io = require('../../globals/io');
+const logger = require('../../globals/logger').child('roomCameraSocket');
+const { getMode, MODES } = require('../modeManager');
+const { isAdmin, isLockdownAdmin, getRole } = require('../roleService');
+
+const SUBSCRIBE_LIMIT = 50;
+const SUBSCRIBE_WINDOW_MS = 10000;
+const STREAM_INTERVAL_MS = 1000;
+
+function passesMode(socket) {
+  const mode = getMode();
+  if (mode === MODES.LOCKDOWN) return isLockdownAdmin(socket);
+  if (mode === MODES.ADMIN) {
+    const role = getRole(socket);
+    return role === 'spectator' || isAdmin(socket);
+  }
+  return true;
+}
+
+function registerRoomCameraSocketGateway({ getRoomCamera, getRoomCameras, getRoomCameraState, roomCameraStreamEvents }) {
+  const cameraSubscribers = new Map();
+  const socketSubscriptions = new Map();
+  const subscribeBuckets = new Map();
+  const lastSentBySocket = new Map();
+
+  function addSubscription(socket, cameraId) {
+    if (!cameraSubscribers.has(cameraId)) cameraSubscribers.set(cameraId, new Set());
+    cameraSubscribers.get(cameraId).add(socket.id);
+    if (!socketSubscriptions.has(socket.id)) socketSubscriptions.set(socket.id, new Set());
+    socketSubscriptions.get(socket.id).add(cameraId);
+  }
+
+  function removeSubscription(socketId, cameraId) {
+    const bucket = cameraSubscribers.get(cameraId);
+    if (bucket) {
+      bucket.delete(socketId);
+      if (bucket.size === 0) cameraSubscribers.delete(cameraId);
+    }
+    const socketBucket = socketSubscriptions.get(socketId);
+    if (socketBucket) {
+      socketBucket.delete(cameraId);
+      if (socketBucket.size === 0) socketSubscriptions.delete(socketId);
+    }
+  }
+
+  function removeAllSubscriptions(socketId) {
+    const bucket = socketSubscriptions.get(socketId);
+    if (!bucket) return;
+    bucket.forEach((cameraId) => removeSubscription(socketId, cameraId));
+  }
+
+  function allowSubscribe(socketId) {
+    const now = Date.now();
+    let bucket = subscribeBuckets.get(socketId);
+    if (!bucket || now - bucket.start >= SUBSCRIBE_WINDOW_MS) bucket = { start: now, count: 0 };
+    bucket.count += 1;
+    subscribeBuckets.set(socketId, bucket);
+    return bucket.count <= SUBSCRIBE_LIMIT;
+  }
+
+  function sendFrame(socket, cameraId, payload, buffer) {
+    socket.emit('roomCamera:frame', { id: cameraId, ...payload }, buffer);
+  }
+
+  function sendStatus(socket, cameraId, status) {
+    socket.emit('roomCamera:status', { id: cameraId, ...status });
+  }
+
+  roomCameraStreamEvents.on('frame', ({ id, buffer, ts }) => {
+    const bucket = cameraSubscribers.get(id);
+    if (!bucket || !buffer) return;
+    bucket.forEach((socketId) => {
+      const socket = io.sockets.sockets.get(socketId);
+      if (!socket) return;
+      let lastMap = lastSentBySocket.get(socketId);
+      if (!lastMap) {
+        lastMap = new Map();
+        lastSentBySocket.set(socketId, lastMap);
+      }
+      const lastSent = lastMap.get(id) || 0;
+      const now = ts || Date.now();
+      if (now - lastSent < STREAM_INTERVAL_MS) return;
+      lastMap.set(id, now);
+      sendFrame(socket, id, { ts }, buffer);
+    });
+  });
+
+  roomCameraStreamEvents.on('status', ({ id, error }) => {
+    const bucket = cameraSubscribers.get(id);
+    if (!bucket) return;
+    bucket.forEach((socketId) => {
+      const socket = io.sockets.sockets.get(socketId);
+      if (!socket) return;
+      sendStatus(socket, id, { error: error || null });
+    });
+  });
+
+  io.on('connection', (socket) => {
+    socket.on('roomCamera:subscribe', (payload = {}, cb = () => {}) => {
+      const list = Array.isArray(payload?.ids)
+        ? payload.ids.map(String)
+        : payload?.roomCameraId || payload?.id
+        ? [String(payload.roomCameraId || payload.id)]
+        : getRoomCameras().map((cam) => cam.id);
+      const uniqueIds = Array.from(new Set(list));
+      try {
+        if (!allowSubscribe(socket.id)) return cb({ error: 'Rate limited' });
+        if (!passesMode(socket)) throw new Error('Not authorized for room camera');
+        const validIds = uniqueIds.filter((id) => !!getRoomCamera(id));
+        validIds.forEach((cameraId) => addSubscription(socket, cameraId));
+        validIds.forEach((cameraId) => {
+          const state = getRoomCameraState(cameraId);
+          if (state?.frame) sendFrame(socket, cameraId, { ts: state.ts }, state.frame);
+          sendStatus(socket, cameraId, { ts: state?.ts || null, error: state?.error || null });
+        });
+        cb({ ok: true, subscribed: validIds });
+      } catch (err) {
+        logger.warn('Room camera subscribe failed', { socketId: socket.id, err: err.message });
+        cb({ error: err.message });
+      }
+    });
+
+    socket.on('roomCamera:unsubscribe', (payload = {}) => {
+      const list = Array.isArray(payload?.ids)
+        ? payload.ids.map(String)
+        : payload?.roomCameraId || payload?.id
+        ? [String(payload.roomCameraId || payload.id)]
+        : [];
+      list.forEach((cameraId) => removeSubscription(socket.id, cameraId));
+    });
+
+    socket.on('disconnect', () => {
+      removeAllSubscriptions(socket.id);
+      subscribeBuckets.delete(socket.id);
+      lastSentBySocket.delete(socket.id);
+    });
+  });
+}
+
+module.exports = {
+  registerRoomCameraSocketGateway,
+};