Initial WatchLink scaffold

server.js

@@ -0,0 +1,70 @@
+const { createServer } = require("node:http");
+const next = require("next");
+const { Server } = require("socket.io");
+
+const dev = process.env.NODE_ENV !== "production";
+const hostname = process.env.HOSTNAME || "0.0.0.0";
+const port = Number(process.env.PORT || 3000);
+
+const app = next({ dev, hostname, port });
+const handle = app.getRequestHandler();
+
+const roomStates = new Map();
+
+app.prepare().then(() => {
+  const httpServer = createServer((req, res) => handle(req, res));
+  const io = new Server(httpServer, {
+    path: "/api/socket",
+    cors: {
+      origin: process.env.NEXTAUTH_URL || "http://localhost:3000"
+    }
+  });
+
+  io.on("connection", (socket) => {
+    socket.on("room:join", ({ roomSlug, user }) => {
+      if (!roomSlug) return;
+      socket.join(roomSlug);
+      socket.data.roomSlug = roomSlug;
+      socket.data.user = user || "Guest";
+      socket.emit("room:state", roomStates.get(roomSlug) || null);
+      socket.to(roomSlug).emit("presence:join", { user: socket.data.user });
+    });
+
+    socket.on("media:set", (payload) => updateRoom(socket, "media:set", payload));
+    socket.on("playback:play", (payload) => updateRoom(socket, "playback:play", payload));
+    socket.on("playback:pause", (payload) => updateRoom(socket, "playback:pause", payload));
+    socket.on("playback:seek", (payload) => updateRoom(socket, "playback:seek", payload));
+    socket.on("chat:message", (payload) => relayRoom(socket, "chat:message", payload));
+
+    socket.on("disconnect", () => {
+      if (socket.data.roomSlug) {
+        socket.to(socket.data.roomSlug).emit("presence:leave", { user: socket.data.user || "Guest" });
+      }
+    });
+  });
+
+  function relayRoom(socket, event, payload) {
+    const roomSlug = socket.data.roomSlug;
+    if (!roomSlug) return;
+    io.to(roomSlug).emit(event, { ...payload, user: socket.data.user || "Guest", at: Date.now() });
+  }
+
+  function updateRoom(socket, event, payload) {
+    const roomSlug = socket.data.roomSlug;
+    if (!roomSlug) return;
+    const previous = roomStates.get(roomSlug) || {};
+    const nextState = {
+      ...previous,
+      ...payload,
+      lastEvent: event,
+      updatedBy: socket.data.user || "Guest",
+      updatedAt: Date.now()
+    };
+    roomStates.set(roomSlug, nextState);
+    io.to(roomSlug).emit(event, nextState);
+  }
+
+  httpServer.listen(port, hostname, () => {
+    console.log(`WatchLink ready on http://${hostname}:${port}`);
+  });
+});