export function formatRupiah(value: number): string {
  const formatted = Math.abs(value).toLocaleString('id-ID');
  return `${value < 0 ? '-' : ''}Rp ${formatted}`;
}

/** Format angka mentah (string digit) jadi ribuan ber-titik, misal "50000" -> "50.000" */
export function formatRibuan(raw: string): string {
  if (!raw) return '';
  const n = Number(raw);
  if (!Number.isFinite(n)) return raw;
  return n.toLocaleString('id-ID');
}

export function formatRupiahShort(value: number): string {
  if (Math.abs(value) >= 1_000_000) {
    const juta = value / 1_000_000;
    return `Rp ${juta.toLocaleString('id-ID', { maximumFractionDigits: 1 })} jt`;
  }
  if (Math.abs(value) >= 1_000) {
    const ribu = value / 1_000;
    return `Rp ${ribu.toLocaleString('id-ID', { maximumFractionDigits: 1 })} rb`;
  }
  return formatRupiah(value);
}

export function formatDate(iso: string): string {
  const d = new Date(iso);
  return d.toLocaleDateString('id-ID', {
    day: 'numeric',
    month: 'short',
    year: 'numeric',
  });
}

export function formatDateTime(iso: string): string {
  const d = new Date(iso);
  const date = d.toLocaleDateString('id-ID', { day: 'numeric', month: 'short' });
  const time = d.toLocaleTimeString('id-ID', {
    hour: '2-digit',
    minute: '2-digit',
  });
  return `${date} · ${time}`;
}

export function todayLabel(): string {
  return new Date().toLocaleDateString('id-ID', {
    weekday: 'long',
    day: 'numeric',
    month: 'long',
    year: 'numeric',
  });
}

/** Kunci minggu ISO sederhana: tanggal Senin (YYYY-MM-DD) */
export function isoWeekKey(d: Date): string {
  const date = new Date(d);
  const day = date.getDay() || 7; // Senin=1, ..., Minggu=7
  date.setDate(date.getDate() - (day - 1));
  date.setHours(0, 0, 0, 0);
  return date.toISOString().slice(0, 10);
}

export function shiftWeekKey(key: string, deltaWeeks: number): string {
  const monday = new Date(`${key}T00:00:00Z`);
  monday.setUTCDate(monday.getUTCDate() + deltaWeeks * 7);
  return monday.toISOString().slice(0, 10);
}