export function formatCurrency(
  amount: number | string,
  currency: string,
): string {
  const num = Number(amount) || 0;
  switch (currency) {
    case "EUR":
      return `${num.toLocaleString("cs-CZ", { minimumFractionDigits: 2, maximumFractionDigits: 2 })} €`;
    case "USD":
      return `$${num.toLocaleString("en-US", { minimumFractionDigits: 2, maximumFractionDigits: 2 })}`;
    case "CZK":
      return `${num.toLocaleString("cs-CZ", { minimumFractionDigits: 2, maximumFractionDigits: 2 })} Kč`;
    case "GBP":
      return `£${num.toLocaleString("en-US", { minimumFractionDigits: 2, maximumFractionDigits: 2 })}`;
    default:
      return `${num.toFixed(2)} ${currency}`;
  }
}

export function formatDate(dateStr: string | null | undefined): string {
  if (!dateStr) return "—";
  const d = new Date(dateStr);
  return d.toLocaleDateString("cs-CZ");
}

/**
 * Today's date as `YYYY-MM-DD` in LOCAL (Prague) time — use this for
 * date-input defaults. `new Date().toISOString().slice(0, 10)` gives the UTC
 * date, which is a day behind the Czech date during the post-midnight window
 * (Prague is UTC+1/+2), so a "today" default could land on yesterday.
 */
export function todayLocalStr(): string {
  const d = new Date();
  const m = String(d.getMonth() + 1).padStart(2, "0");
  const day = String(d.getDate()).padStart(2, "0");
  return `${d.getFullYear()}-${m}-${day}`;
}

export function formatKm(km: number | string): string {
  return new Intl.NumberFormat("cs-CZ").format(Number(km) || 0);
}

export function czechPlural(
  n: number,
  one: string,
  few: string,
  many: string,
): string {
  if (n === 1) return one;
  if (n >= 2 && n <= 4) return few;
  return many;
}