export const UI_LOCALE = 'nl-BE';
export const UI_TIME_ZONE = 'Europe/Brussels';

const numberFormatter = new Intl.NumberFormat(UI_LOCALE);
const decimalFormatter = new Intl.NumberFormat(UI_LOCALE, { maximumFractionDigits: 1 });
const dateTimeFormatter = new Intl.DateTimeFormat(UI_LOCALE, { dateStyle: 'medium', timeStyle: 'short', timeZone: UI_TIME_ZONE });
export const NEVER_RECEIVED = 'Nooit ontvangen';

export function formatNumber(value: number, maximumFractionDigits?: number): string {
  if (!Number.isFinite(value)) return '—';
  return (maximumFractionDigits === undefined ? numberFormatter : new Intl.NumberFormat(UI_LOCALE, { maximumFractionDigits })).format(value);
}

export function formatDecimal(value: number): string {
  return Number.isFinite(value) ? decimalFormatter.format(value) : '—';
}

export function formatDateTime(value?: string): string {
  if (!hasReceivedTimestamp(value)) return NEVER_RECEIVED;
  const date = new Date(value);
  return dateTimeFormatter.format(date);
}

/** Rejects transport zero-values and invalid input before they reach a visible <time>. */
export function hasReceivedTimestamp(value?: string): value is string {
  if (!value?.trim()) return false;
  const date = new Date(value);
  return Number.isFinite(date.valueOf()) && date.valueOf() > 0 && date.getUTCFullYear() > 1;
}

export function formatPercent(value?: number, maximumFractionDigits = 1): string {
  return value === undefined || !Number.isFinite(value) ? '—' : new Intl.NumberFormat(UI_LOCALE, { maximumFractionDigits, style: 'percent' }).format(value / 100);
}