// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// TODO(crbug.com/1172300) Ignored during the jsdoc to ts migration
// eslint-disable-next-line @typescript-eslint/naming-convention
let _measuredScrollbarWidth: number|undefined;

export function resetMeasuredScrollbarWidthForTest(): void {
  _measuredScrollbarWidth = undefined;
}

export function measuredScrollbarWidth(document?: Document|null): number {
  if (typeof _measuredScrollbarWidth === 'number') {
    return _measuredScrollbarWidth;
  }
  if (!document) {
    return 16;
  }

  const scrollDiv = document.createElement('div');
  const innerDiv = document.createElement('div');
  scrollDiv.setAttribute('style', 'display: block; width: 100px; height: 100px; overflow: scroll;');
  innerDiv.setAttribute('style', 'height: 200px');
  scrollDiv.appendChild(innerDiv);
  document.body.appendChild(scrollDiv);
  _measuredScrollbarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth;
  document.body.removeChild(scrollDiv);
  return _measuredScrollbarWidth;
}