improving the UI side of ptz... and improving the way turns works with UI....

server/src/services/ptzCameraService/participation.js

@@ -0,0 +1,89 @@
+// Owns PTZ turns only. Camera IO, permissions and operating-mode entry are supplied
+// by the service, so queue transitions cannot create physical rover ownership.
+function createParticipation({ io, events, emitChange, getTurnDurationMs, canParticipate, stopMotion, revokeVideo }) {
+  const state = { operatorSocketId: null, queue: [], deadline: null, generation: 0 };
+  let timer = null;
+
+  function remove(socketId) {
+    state.queue = state.queue.filter((id) => id !== socketId);
+  }
+
+  function stopOperator(reason) {
+    clearTimeout(timer);
+    timer = null;
+    const previous = state.operatorSocketId;
+    state.operatorSocketId = null;
+    state.deadline = null;
+    state.generation += 1;
+    if (!previous) return;
+    revokeVideo(previous);
+    stopMotion(reason).catch(() => {});
+    events.emit('operator', { socketId: previous, action: 'release', reason });
+  }
+
+  function scheduleTurn() {
+    clearTimeout(timer);
+    const duration = getTurnDurationMs();
+    state.deadline = Date.now() + duration;
+    timer = setTimeout(() => {
+      // An expired operator stays when alone, but is not automatically requeued
+      // when another participant takes over. Preserve the existing PTZ rule.
+      state.queue = state.queue.filter((id) => eligible(id));
+      if (state.queue.length) {
+        stopOperator('turn-expired');
+        advance('turn-expired');
+      } else {
+        scheduleTurn();
+        emitChange('turn-extended-empty-queue');
+      }
+    }, duration);
+  }
+
+  function eligible(socketId) {
+    const socket = io.sockets.sockets.get(socketId);
+    return socket && !socket.disconnected && canParticipate(socket);
+  }
+
+  function advance(reason) {
+    while (!state.operatorSocketId && state.queue.length) {
+      const next = state.queue.shift();
+      if (!eligible(next)) continue;
+      state.operatorSocketId = next;
+      state.generation += 1;
+      scheduleTurn();
+      events.emit('operator', { socketId: next, action: 'active' });
+    }
+    emitChange(reason);
+  }
+
+  function claim(socket) {
+    if (!eligible(socket.id)) throw new Error('PTZ participation required');
+    if (state.operatorSocketId === socket.id || state.queue.includes(socket.id)) return;
+    state.queue.push(socket.id);
+    advance('queue-join');
+  }
+
+  function release(socketId, reason = 'turn-release') {
+    remove(socketId);
+    if (state.operatorSocketId === socketId) stopOperator(reason);
+    advance(reason);
+  }
+
+  function reconcile() {
+    state.queue = state.queue.filter(eligible);
+    if (state.operatorSocketId && !eligible(state.operatorSocketId)) stopOperator('access-change');
+    advance('access-change');
+  }
+
+  function clear(reason) {
+    state.queue = [];
+    stopOperator(reason);
+  }
+
+  return {
+    state, claim, release, reconcile, clear,
+    revoke: (reason) => { stopOperator(reason); advance(reason); },
+  };
+}
+
+module.exports = { createParticipation };