/**
 * Where the client navigation in flight is going (BUG-1040).
 *
 * Next's app router renders the next page first and writes the address bar
 * afterwards (HistoryUpdater, an insertion effect). A page that decides its
 * first frame from the URL — Home's warm return reads `?new=1` / `?c=` — would
 * otherwise read the page it is leaving. `AppLink` and `navigateAppPath` note
 * the href here just before the router starts; the page takes it once.
 *
 * Memory only, no dependencies (it ships with the shared sidebar).
 */

const MAX_AGE_MS = 10_000;

let target: { href: string; at: number } | null = null;

export function noteClientNavigationTarget(href: string): void {
  if (!href.startsWith("/") || href.startsWith("//")) return;
  target = { href, at: Date.now() };
}

/** The noted href (then forgotten), or null when none is recent enough to trust. */
export function takeClientNavigationTarget(now = Date.now()): string | null {
  const noted = target;
  target = null;
  if (!noted || now - noted.at > MAX_AGE_MS) return null;
  return noted.href;
}