export function relativeTime(ts: number): string {
  const diff = Date.now() - ts;
  const s = Math.round(diff / 1000);
  if (s < 45) return "just now";
  const m = Math.round(s / 60);
  if (m < 60) return `${m}m`;
  const h = Math.round(m / 60);
  if (h < 24) return `${h}h`;
  const d = Math.round(h / 24);
  if (d < 7) return `${d}d`;
  return new Date(ts).toLocaleDateString(undefined, { month: "short", day: "numeric" });
}

export function clockTime(ts: number): string {
  return new Date(ts).toLocaleTimeString(undefined, {
    hour: "numeric",
    minute: "2-digit",
  });
}

export function dayLabel(ts: number): string {
  const d = new Date(ts);
  const today = new Date();
  const yst = new Date();
  yst.setDate(today.getDate() - 1);
  if (d.toDateString() === today.toDateString()) return "Today";
  if (d.toDateString() === yst.toDateString()) return "Yesterday";
  return d.toLocaleDateString(undefined, { weekday: "long", month: "long", day: "numeric" });
}

export function groupByDay<T extends { ts: number }>(items: T[]): { day: string; items: T[] }[] {
  const out: { day: string; items: T[] }[] = [];
  for (const it of items) {
    const label = dayLabel(it.ts);
    const last = out[out.length - 1];
    if (last && last.day === label) last.items.push(it);
    else out.push({ day: label, items: [it] });
  }
  return out;
}