/**
 * Combines multiple AbortSignals into one that aborts when any input does.
 * Prefers the native `AbortSignal.any` where present (modern browsers);
 * falls back to manual event-listener wiring where it isn't.
 *
 * That fallback is load-bearing, not defensive padding: React Native
 * doesn't provide a native AbortController at all — `setUpXHR.js` installs
 * one from the third-party `abort-controller` npm package (pinned at
 * v3.0.0 in this tree), which predates `AbortSignal.any` entering the
 * WHATWG spec. Calling it unconditionally on native evaluates to invoking
 * `undefined` as a function, which Hermes reports as the unhelpfully
 * generic "undefined is not a function" — confirmed for real on
 * 2026-08-17, the first time a native call site (a vault item detail
 * screen, via its own cancellation AbortSignal) exercised the
 * `signals.length > 1` branch this function has always had; every
 * previous native caller only ever supplied the internal timeout signal,
 * so `AbortSignal.any` had simply never been reached before.
 */
function combineSignals(signals: readonly AbortSignal[]): AbortSignal {
  if (signals.length === 1) {
    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion -- length checked
    return signals[0]!;
  }
  if (typeof AbortSignal.any === "function") {
    return AbortSignal.any([...signals]);
  }
  const combined = new AbortController();
  for (const s of signals) {
    if (s.aborted) {
      combined.abort();
      break;
    }
    s.addEventListener("abort", () => combined.abort(), { once: true });
  }
  return combined.signal;
}

/**
 * `fetch` with a timeout abort signal merged onto the caller's own signal.
 * The default timeout is 15s. Pass `Infinity` to disable the timeout
 * (the caller's own `signal` still applies). Passing `0` aborts
 * immediately — almost never what you want — so we treat any
 * non-positive value as "no timeout" to avoid the footgun.
 *
 * **Lockstep duplicate** of `vault/clients/shared/src/utils/fetch.ts`.
 * `@vault/shared` is the vault-specific lower layer; `@entropy-softworks/ui`
 * is the cross-portfolio UI package. Neither can depend on the other
 * (shared → ui would invert layering; ui → shared would chain every
 * downstream Entropy Softworks app to vault). The function is small,
 * pure, and stable; keep both copies byte-identical and update both
 * when changing.
 */
export function fetchWithTimeout(
  url: string,
  options: RequestInit = {},
  timeoutMs = 15000
): Promise<Response> {
  const controller = new AbortController();
  const id =
    timeoutMs > 0 && Number.isFinite(timeoutMs)
      ? setTimeout(() => controller.abort(), timeoutMs)
      : null;
  const signals = [controller.signal, options.signal].filter((s): s is AbortSignal => s != null);
  const combinedSignal = combineSignals(signals);
  return fetch(url, { ...options, signal: combinedSignal }).finally(() => {
    if (id !== null) {
      clearTimeout(id);
    }
  });
}