function formatCadCoord(v: number | null): string {
  if (v === null || !Number.isFinite(v)) return '—';
  const abs = Math.abs(v);
  const digits = abs >= 1e6 ? 1 : abs >= 1e3 ? 2 : abs >= 1 ? 3 : 4;
  return v.toFixed(digits);
}

export interface CoordReadoutProps {
  point: { x: number; y: number; z: number } | null;
  spaceKind: 'model' | 'paper' | 'other' | null;
}

export function CoordReadout({ point, spaceKind }: CoordReadoutProps) {
  const unitLabel = spaceKind === 'paper' ? 'Paper' : 'UCS';
  return (
    <div
      className="pointer-events-none fixed bottom-3 right-3 z-10 rounded-md border bg-card/90 px-3 py-1.5 font-mono text-xs text-muted-foreground shadow-sm backdrop-blur"
      title={`마우스 위치 CAD 좌표 (${spaceKind === 'paper' ? 'Layout=Paper' : 'Model=UCS'} 도면단위)`}
    >
      X {formatCadCoord(point?.x ?? null)} · Y {formatCadCoord(point?.y ?? null)}{' '}
      <span className="opacity-60">({unitLabel})</span>
    </div>
  );
}