/**
 * Process-wide cache for `Intl.NumberFormat` / `Intl.DateTimeFormat`
 * instances, keyed by locale + options.
 *
 * Constructing an `Intl.*` formatter is comparatively expensive; several
 * list-item helpers built one per row per render (`workout-list`,
 * `recent-workouts-tile`, `medication-card`, …). These getters return a cached
 * instance so the construction cost is paid once per distinct (locale, options)
 * shape instead of once per call. Formatters are immutable + stateless, so
 * sharing a single instance across calls is safe.
 *
 * Keyed by `locale + " " + JSON.stringify(options)`; stringifying the
 * (tiny, literal) options object per call is orders of magnitude cheaper than
 * a formatter construction. The set of distinct shapes is bounded and small,
 * so the cache never needs eviction.
 */
const numberFormatters = new Map<string, Intl.NumberFormat>();
const dateTimeFormatters = new Map<string, Intl.DateTimeFormat>();

export function getNumberFormat(
  locale: string,
  options: Intl.NumberFormatOptions,
): Intl.NumberFormat {
  const key = `${locale} ${JSON.stringify(options)}`;
  let fmt = numberFormatters.get(key);
  if (!fmt) {
    fmt = new Intl.NumberFormat(locale, options);
    numberFormatters.set(key, fmt);
  }
  return fmt;
}

export function getDateTimeFormat(
  locale: string,
  options: Intl.DateTimeFormatOptions,
): Intl.DateTimeFormat {
  const key = `${locale} ${JSON.stringify(options)}`;
  let fmt = dateTimeFormatters.get(key);
  if (!fmt) {
    fmt = new Intl.DateTimeFormat(locale, options);
    dateTimeFormatters.set(key, fmt);
  }
  return fmt;
}