export function formatDate(iso: string | null | undefined, opts?: { relative?: boolean }): string {
  if (!iso) return "—";
  const d = new Date(iso);
  if (Number.isNaN(d.getTime())) return iso;
  if (opts?.relative) {
    const diffMs = d.getTime() - Date.now();
    const absMs = Math.abs(diffMs);
    const sec = Math.round(absMs / 1000);
    const min = Math.round(sec / 60);
    const hr = Math.round(min / 60);
    const day = Math.round(hr / 24);
    const past = diffMs < 0;
    if (sec < 45) return past ? "just now" : "in a moment";
    if (min < 60) return past ? `${min}m ago` : `in ${min}m`;
    if (hr < 24) return past ? `${hr}h ago` : `in ${hr}h`;
    if (day < 30) return past ? `${day}d ago` : `in ${day}d`;
  }
  return d.toLocaleString(undefined, { dateStyle: "medium", timeStyle: "short" });
}

export function formatBytes(bytes: number | null | undefined): string {
  if (bytes == null) return "—";
  if (bytes < 1024) return `${bytes} B`;
  const units = ["KB", "MB", "GB", "TB"];
  let value = bytes / 1024;
  let unitIdx = 0;
  while (value >= 1024 && unitIdx < units.length - 1) {
    value /= 1024;
    unitIdx++;
  }
  return `${value.toFixed(value >= 10 ? 0 : 1)} ${units[unitIdx]}`;
}

export function truncate(str: string, max: number): string {
  if (str.length <= max) return str;
  return str.slice(0, Math.max(0, max - 1)) + "…";
}