live action

backend/src/index.ts

@@ -32,6 +32,29 @@ const io = new Server(server, {
   }
 });
 
+let counter = 0;
+let counterTimer: NodeJS.Timeout | null = null;
+
+const broadcastCounter = () => {
+  io.emit("counter:update", { value: counter });
+};
+
+const startCounter = () => {
+  if (counterTimer) return;
+  counterTimer = setInterval(() => {
+    counter += 1;
+    broadcastCounter();
+  }, 1000);
+};
+
+const stopCounter = () => {
+  if (counterTimer) {
+    clearInterval(counterTimer);
+    counterTimer = null;
+  }
+  io.emit("counter:stopped", { value: counter });
+};
+
 io.use((socket, next) => {
   const token = socket.handshake.auth?.token as string | undefined;
   if (!token) {
@@ -51,6 +74,20 @@ io.on("connection", (socket) => {
   socket.on("ping", () => {
     socket.emit("pong", "pong");
   });
+
+  socket.on("counter:start", (ack?: (payload: { running: boolean; value: number }) => void) => {
+    startCounter();
+    ack?.({ running: true, value: counter });
+  });
+
+  socket.on("counter:stop", (ack?: (payload: { running: boolean; value: number }) => void) => {
+    stopCounter();
+    ack?.({ running: false, value: counter });
+  });
+
+  socket.on("counter:status", (ack?: (payload: { running: boolean; value: number }) => void) => {
+    ack?.({ running: !!counterTimer, value: counter });
+  });
 });
 
 async function start() {