/**
 * Locale-aware walking-distance formatting.
 *
 * Distances are stored as Int meters. Under 1000 m they render as whole
 * meters, above that as kilometers with one decimal (e.g. "1.2 km"). Reused by
 * the tracking card, the team leaderboards and the profile distances.
 */
export function useFormatDistance() {
  const { locale } = useI18n();

  function formatDistance(meters: number | null | undefined): string {
    const value = meters ?? 0;
    const loc = locale.value || 'en';

    if (value < 1000) {
      return new Intl.NumberFormat(loc, {
        style: 'unit',
        unit: 'meter',
        maximumFractionDigits: 0
      }).format(Math.round(value));
    }

    return new Intl.NumberFormat(loc, {
      style: 'unit',
      unit: 'kilometer',
      maximumFractionDigits: 1
    }).format(value / 1000);
  }

  return { formatDistance };
}