/**
 * Get the vertical and horizontal scrollbar sizes
 * Got from https://stackoverflow.com/questions/986937/how-can-i-get-the-browsers-scrollbar-sizes
 *
 * @returns {Array} Array containing the scrollbar horizontal and vertical sizes
 */
export default function getScrollbarSize() {
  const inner = document.createElement('p');
  inner.style.width = '100%';
  inner.style.height = '100%';

  const outer = document.createElement('div');
  outer.style.position = 'absolute';
  outer.style.top = '0px';
  outer.style.left = '0px';
  outer.style.visibility = 'hidden';
  outer.style.width = '100px';
  outer.style.height = '100px';
  outer.style.overflow = 'hidden';
  outer.appendChild(inner);

  document.body.appendChild(outer);

  const w1 = inner.offsetWidth;
  const h1 = inner.offsetHeight;
  outer.style.overflow = 'scroll';
  let w2 = inner.offsetWidth;
  let h2 = inner.offsetHeight;

  if (w1 === w2) {
    w2 = outer.clientWidth;
  }

  if (h1 === h2) {
    h2 = outer.clientHeight;
  }

  document.body.removeChild(outer);

  return [w1 - w2, h1 - h2];
}