[#152] feat: 이용자 수 구독 로직 구현

backend/src/socket.ts

@@ -0,0 +1,55 @@
+import { Application } from 'express';
+import http from 'http';
+import { Server, Socket } from 'socket.io';
+
+const webSocket = (server: http.Server, app: Application, session: any) => {
+  const io = new Server(server, { path: '/socket.io' });
+
+  app.set('io', io);
+  const page = io.of('/page');
+  const pageList = io.of('/pageList');
+
+  io.use((socket, next) => {
+    session(socket.request, {}, next);
+  });
+
+  pageList.on('connection', (socket: Socket) => {
+    const req = socket.request;
+    const ip = req.headers['x-forwarded-for'] || req.connection.remoteAddress;
+    pageList.emit('allUserCount', pageList.sockets.size);
+    socket.on('disconnect', () => {
+      pageList.emit('allUserCount', pageList.sockets.size);
+    });
+  });
+
+  page.on('connection', (socket: Socket) => {
+    const req = socket.request as any;
+    const ip = req.headers['x-forwarded-for'] || req.connection.remoteAddress;
+    const leaveBeforeRoom = (socket: Socket) => {
+      socket.rooms.forEach((room) => {
+        socket.leave(room);
+        const clientsSize = (page.adapter as any).rooms.get(room)?.size;
+        page.to(room).emit('pageUserCount', clientsSize ?? 0);
+      });
+    };
+    leaveBeforeRoom(socket);
+    socket.on('disconnect', () => {
+      leaveBeforeRoom(socket);
+    });
+
+    socket.on('error', (error) => {
+      console.error(error);
+      leaveBeforeRoom(socket);
+    });
+
+    socket.on('join', (pageId) => {
+      leaveBeforeRoom(socket);
+      socket.join(pageId);
+      page
+        .to(pageId)
+        .emit('pageUserCount', (page.adapter as any).rooms.get(pageId).size);
+    });
+  });
+};
+
+export default webSocket;