/** Browser / WebView fetch failures are usually TypeError with an opaque message. */

export const AI_NETWORK_ERROR_CODE = "AI_UNREACHABLE";

const NETWORK_FETCH_HINTS = [
  "failed to fetch",
  "networkerror",
  "network request failed",
  "load failed",
  "internet connection appears to be offline",
];

export function isLikelyNetworkFetchError(error: unknown): boolean {
  const name = error instanceof Error ? error.name : "";
  const msg = (error instanceof Error ? error.message : String(error ?? "")).toLowerCase();
  if (msg === AI_NETWORK_ERROR_CODE.toLowerCase()) return true;
  if (NETWORK_FETCH_HINTS.some((hint) => msg.includes(hint))) return true;
  // Some WebViews surface a bare TypeError when fetch cannot complete.
  return name === "TypeError" && !msg;
}

export function formatNetworkAwareMessage(
  template: string,
  error: unknown,
  networkCopy: string,
): string {
  const raw = error instanceof Error ? error.message : String(error ?? "");
  const message = isLikelyNetworkFetchError(error) || isLikelyNetworkFetchError(raw) ? networkCopy : raw;
  if (template.includes("{message}")) {
    return template.split("{message}").join(String(message));
  }
  return isLikelyNetworkFetchError(error) || isLikelyNetworkFetchError(raw) ? networkCopy : template;
}