no-whatever/src/app/api/room/[id]/events/route.ts

import { buildRoomStatus } from "@/lib/buildRoomStatus";
import { getRoomData } from "@/lib/store";
import { subscribe } from "@/lib/roomEvents";

export const dynamic = "force-dynamic";

export async function GET(
  req: Request,
  { params }: { params: Promise<{ id: string }> },
) {
  const { id } = await params;

  const url = new URL(req.url);
  const userId = url.searchParams.get("userId");

  if (userId) {
    const data = await getRoomData(id);
    if (data && !data.users.includes(userId)) {
      return new Response(JSON.stringify({ error: "not_a_member" }), {
        status: 403,
        headers: { "Content-Type": "application/json" },
      });
    }
  }

  const encoder = new TextEncoder();

  const stream = new ReadableStream({
    start(controller) {
      const send = (obj: object) => {
        try {
          controller.enqueue(
            encoder.encode(`data: ${JSON.stringify(obj)}\n\n`),
          );
        } catch {
          /* controller already closed */
        }
      };

      let alive = true;

      (async () => {
        try {
          const status = await buildRoomStatus(id);
          if (!status) {
            send({ error: "room_not_found" });
            controller.close();
            return;
          }
          if (alive) send(status);
        } catch {
          send({ error: "load_failed" });
          controller.close();
        }
      })();

      const unsubscribe = subscribe(id, async () => {
        if (!alive) return;
        try {
          const status = await buildRoomStatus(id);
          if (status && alive) send(status);
        } catch {
          /* ignore transient read errors */
        }
      });

      const heartbeat = setInterval(() => {
        try {
          controller.enqueue(encoder.encode(": heartbeat\n\n"));
        } catch {
          clearInterval(heartbeat);
        }
      }, 30_000);

      req.signal.addEventListener("abort", () => {
        alive = false;
        unsubscribe();
        clearInterval(heartbeat);
        try {
          controller.close();
        } catch {
          /* already closed */
        }
      });
    },
  });

  return new Response(stream, {
    headers: {
      "Content-Type": "text/event-stream",
      "Cache-Control": "no-cache, no-transform",
      Connection: "keep-alive",
    },
  });
}