export function timeAgo(iso: string | number | Date): string {
  const d = typeof iso === "string" || typeof iso === "number" ? new Date(iso) : iso;
  const sec = Math.round((Date.now() - d.getTime()) / 1000);
  if (!isFinite(sec) || sec < 0) return "";
  if (sec < 45) return "just now";
  const min = Math.round(sec / 60);
  if (min < 60) return `${min}m ago`;
  const hr = Math.round(min / 60);
  if (hr < 24) return `${hr}h ago`;
  const day = Math.round(hr / 24);
  if (day < 30) return `${day}d ago`;
  const mo = Math.round(day / 30);
  if (mo < 12) return `${mo}mo ago`;
  const yr = Math.round(mo / 12);
  return `${yr}y ago`;
}

// Format a duration in hours as "H.Hh" under a day, otherwise "Dd Hh".
export function formatHours(hours: number): string {
  if (!isFinite(hours) || hours <= 0) return "0h";
  if (hours < 1) {
    const m = Math.round(hours * 60);
    return `${m}m`;
  }
  if (hours < 24) return `${hours.toFixed(1)}h`;
  const days = Math.floor(hours / 24);
  const rem = Math.round(hours - days * 24);
  return rem ? `${days}d ${rem}h` : `${days}d`;
}

export function formatBytes(n: number): string {
  if (!isFinite(n) || n <= 0) return "0 B";
  const units = ["B", "KB", "MB", "GB", "TB"];
  const i = Math.min(Math.floor(Math.log(n) / Math.log(1024)), units.length - 1);
  return `${(n / Math.pow(1024, i)).toFixed(i === 0 ? 0 : 1)} ${units[i]}`;
}