import { fetchLatestBar } from "../../lib/alpacaClient";

export async function loader({ request }: { request: Request }) {
  const url = new URL(request.url);
  const ticker = (url.searchParams.get("ticker") || "").toUpperCase();
  if (!ticker) return new Response("ticker required", { status: 400 });
  const timeframe = url.searchParams.get("timeframe") || "1Min"; // default to 1Min bars for live price
  const mode = url.searchParams.get("mode") === "live" ? 'live' : 'paper';

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

  // Create a ReadableStream that polls latest bar every second and pushes SSE
  let closed = false;
  let interval: any;
  const stream = new ReadableStream({
    start(controller) {
      // helper to push SSE event
      function pushEvent(obj: any) {
        try {
          const payload = `data: ${JSON.stringify(obj)}\n\n`;
          controller.enqueue(new TextEncoder().encode(payload));
        } catch (e) {
          console.warn("price-stream: failed to enqueue", e);
        }
      }

      // initial ping
      pushEvent({ event: "connected", ticker, timeframe });

      interval = setInterval(async () => {
        if (closed) return;
        try {
          const last = await fetchLatestBar(ticker, timeframe, mode);
          const price = last ? (last.ClosePrice ?? last.c ?? null) : null;
          if (price != null) {
            pushEvent({ price, ts: Date.now(), timeframe });
          } else {
            pushEvent({ error: "no_bar", ts: Date.now() });
          }
        } catch (err) {
          console.error("price-stream: error fetching latest bar", err);
          pushEvent({ error: String(err), ts: Date.now() });
          // keep trying
        }
      }, 1000);

      // no-op here; cleanup handled in cancel
    },
    cancel() {
      closed = true;
      clearInterval(interval);
    },
  });

  return new Response(stream, { headers });
}