import { goto } from "$app/navigation";

/**
 * Navigate "back" using real browser/Android history when possible, falling
 * back to an explicit path otherwise.
 *
 * Hardcoded `goto(backPath)` always sends the user to a fixed screen, which
 * loses track of where they actually came from (e.g. reaching the genres list
 * from different entry points). Preferring `history.back()` keeps the back
 * affordance consistent with the platform back gesture and the browser/Android
 * hardware back button.
 *
 * We only use history when there is somewhere to go back to *within the app*.
 * On a fresh deep-link (history length 1, or an external referrer) we fall back
 * to `fallbackPath` so the user never gets stranded or bounced out of the app.
 */
export function navigateBack(fallbackPath: string): void {
  if (canGoBack()) {
    history.back();
  } else {
    goto(fallbackPath);
  }
}

/**
 * True when there is in-app history to pop. `history.length > 1` means the user
 * navigated here from another page in this session rather than landing here
 * directly (deep link, refresh, or first load).
 */
function canGoBack(): boolean {
  if (typeof history === "undefined") return false;
  return history.length > 1;
}