import type { FastifyInstance } from "fastify";
import { requireRole } from "../auth.js";
import { deviceEvents } from "../device-events.js";
import type { PrinterMonitor } from "../printer-monitor.js";

// Live printer-status API. The PrinterMonitor polls printers in the background;
// these endpoints expose its cache (snapshot) and a live push stream (SSE) so the
// booth UI shows paper-out / cover-open / offline in real time. Any authenticated
// operator may read status (it's operational, not a setup action).

export async function printerRoutes(
  app: FastifyInstance,
  monitor: PrinterMonitor,
): Promise<void> {
  const guard = requireRole("admin", "operator", "cashier", "readonly");

  // Current status of every monitored printer (cached — no device round-trip).
  app.get("/api/printers/status", { preHandler: guard }, async () => ({
    printers: monitor.snapshot(),
  }));

  // Live stream: emits the full snapshot on connect, then one event per change.
  // Server-Sent Events — one-way, survives proxies, trivially consumed by the SPA.
  app.get("/api/printers/status/stream", { preHandler: guard }, (req, reply) => {
    reply.raw.writeHead(200, {
      "content-type": "text/event-stream",
      "cache-control": "no-cache",
      connection: "keep-alive",
    });

    const send = (event: string, data: unknown) => {
      reply.raw.write(`event: ${event}\n`);
      reply.raw.write(`data: ${JSON.stringify(data)}\n\n`);
    };

    // Initial state so a fresh client doesn't wait for the next change.
    send("snapshot", { printers: monitor.snapshot() });

    const unsubscribe = deviceEvents.onPrinterStatus((e) => send("status", e));

    // Heartbeat keeps intermediaries from closing an idle connection.
    const heartbeat = setInterval(() => reply.raw.write(": ping\n\n"), 25000);
    heartbeat.unref?.();

    req.raw.on("close", () => {
      clearInterval(heartbeat);
      unsubscribe();
    });
  });
}