import { parseDbDateTime } from './timezone';

// Parses a MySQL DATETIME string correctly regardless of the Node
// process's own timezone — see lib/timezone.ts.
export function parseDbDate(s: string): Date {
  return parseDbDateTime(s);
}

export function diffMinutes(startStr: string, endStr: string | null): number | null {
  if (!endStr) return null;
  const start = parseDbDate(startStr);
  const end = parseDbDate(endStr);
  return Math.round((end.getTime() - start.getTime()) / 60000);
}

// "2h ago", "3d ago", etc. — used for "last connected" displays.
export function formatRelativeTime(dbDateStr: string | null): string {
  if (!dbDateStr) return '—';
  const diffMs = Date.now() - parseDbDate(dbDateStr).getTime();
  const diffMin = Math.round(diffMs / 60_000);
  if (diffMin < 1) return 'just now';
  if (diffMin < 60) return `${diffMin}m ago`;
  const diffHr = Math.round(diffMin / 60);
  if (diffHr < 24) return `${diffHr}h ago`;
  const diffDay = Math.round(diffHr / 24);
  if (diffDay < 30) return `${diffDay}d ago`;
  const diffMonth = Math.round(diffDay / 30);
  if (diffMonth < 12) return `${diffMonth}mo ago`;
  return `${Math.round(diffMonth / 12)}y ago`;
}