export function formatBytes(n: number): string {
  const num = Number(n) || 0;
  if (num < 1024) return `${num} B`;
  const units = ['KiB', 'MiB', 'GiB', 'TiB', 'PiB'];
  let v = num / 1024;
  let i = 0;
  while (v >= 1024 && i < units.length - 1) {
    v /= 1024;
    i++;
  }
  return `${v.toFixed(2)} ${units[i]}`;
}

function pad(n: number): string {
  return n < 10 ? `0${n}` : `${n}`;
}

// Deterministic, timezone-independent date+time formatter.
// Uses UTC getters so the server (UTC) and client (local TZ) render
// byte-identical text, avoiding React hydration mismatches (error #425).
// Output format: "YYYY-MM-DD HH:MM UTC".
export function formatDateTime(s: string | null | undefined): string {
  if (!s) return '—';
  const d = new Date(s);
  if (Number.isNaN(d.getTime())) return '—';
  const date = `${d.getUTCFullYear()}-${pad(d.getUTCMonth() + 1)}-${pad(
    d.getUTCDate(),
  )}`;
  const time = `${pad(d.getUTCHours())}:${pad(d.getUTCMinutes())}`;
  return `${date} ${time} UTC`;
}

// Date-only deterministic UTC formatter. Output format: "YYYY-MM-DD UTC".
export function formatDateOnly(s: string | null | undefined): string {
  if (!s) return '—';
  const d = new Date(s);
  if (Number.isNaN(d.getTime())) return '—';
  return `${d.getUTCFullYear()}-${pad(d.getUTCMonth() + 1)}-${pad(
    d.getUTCDate(),
  )} UTC`;
}

// Backwards-compatible alias: existing call sites render date+time.
export const formatDate = formatDateTime;