import {
  mapTradingBotStatus,
  readBoundedJsonResponse,
  TRADING_BOT_PROXY_PATH,
  TRADING_BOT_STATUS_MAX_BYTES,
  TRADING_BOT_STATUS_TIMEOUT_MS,
  tradingBotStatusUrl,
} from "@rakazo/core";
import type { Hono } from "hono";

export function mountTradingBotStatus(
  app: Hono,
  options: {
    /** Normalized http(s) origin. Unset leaves the route idle for SaaS builds. */
    baseUrl: string | undefined;
    authorize: (request: Request) => Promise<boolean>;
    fetchImpl?: typeof fetch;
  },
) {
  const fetchImpl = options.fetchImpl ?? fetch;
  app.get(TRADING_BOT_PROXY_PATH, async (c) => {
    c.header("cache-control", "no-store");
    if (!options.baseUrl) return c.json({ configured: false });
    const allowed = await options.authorize(c.req.raw).catch(() => false);
    if (!allowed) return c.json({ error: "Unauthorized" }, 401);

    const timeout = linkAbort(c.req.raw.signal, TRADING_BOT_STATUS_TIMEOUT_MS);
    try {
      const response = await fetchImpl(tradingBotStatusUrl(options.baseUrl), {
        method: "GET",
        redirect: "error",
        cache: "no-store",
        signal: timeout.signal,
        headers: { accept: "application/json" },
      });
      if (!response.ok) {
        cancelBody(response);
        return c.json({ configured: true, reachable: false }, 502);
      }
      const body = await readBoundedJsonResponse<unknown>(
        response,
        TRADING_BOT_STATUS_MAX_BYTES,
        timeout.signal,
      );
      const status = mapTradingBotStatus(body);
      return c.json({ configured: true, reachable: true, status: status ?? null });
    } catch {
      return c.json({ configured: true, reachable: false }, 502);
    } finally {
      timeout.cancel();
    }
  });
}

function linkAbort(
  parent: AbortSignal,
  timeoutMs: number,
): { signal: AbortSignal; cancel: () => void } {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), timeoutMs);
  const onParent = () => controller.abort();
  if (parent.aborted) controller.abort();
  else parent.addEventListener("abort", onParent);
  return {
    signal: controller.signal,
    cancel: () => {
      clearTimeout(timer);
      parent.removeEventListener("abort", onParent);
    },
  };
}

function cancelBody(response: Response): void {
  try {
    void Promise.resolve(response.body?.cancel()).catch(() => undefined);
  } catch {
    // Best-effort. The caller still reports the bot as unreachable.
  }
}