export interface ViewportOffsetResult {
  left: number;
  top: number;
  right: number;
  bottom: number;
  rightIncludeBody: number;
  bottomIncludeBody: number;
}

export function getBoundingClientRect(element: Element): DOMRect | number {
  if (!element || !element.getBoundingClientRect) {
    return 0;
  }
  return element.getBoundingClientRect();
}

function trim(string: string) {
  return (string || '').replace(/^[\s\uFEFF]+|[\s\uFEFF]+$/g, '');
}

/* istanbul ignore next */
export function hasClass(el: Element, cls: string) {
  if (!el || !cls) return false;
  if (cls.indexOf(' ') !== -1) throw new Error('className should not contain space.');
  if (el.classList) {
    return el.classList.contains(cls);
  } else {
    return (' ' + el.className + ' ').indexOf(' ' + cls + ' ') > -1;
  }
}

/* istanbul ignore next */
export function addClass(el: Element, cls: string) {
  if (!el) return;
  let curClass = el.className;
  const classes = (cls || '').split(' ');

  for (let i = 0, j = classes.length; i < j; i++) {
    const clsName = classes[i];
    if (!clsName) continue;

    if (el.classList) {
      el.classList.add(clsName);
    } else if (!hasClass(el, clsName)) {
      curClass += ' ' + clsName;
    }
  }
  if (!el.classList) {
    el.className = curClass;
  }
}

/* istanbul ignore next */
export function removeClass(el: Element, cls: string) {
  if (!el || !cls) return;
  const classes = cls.split(' ');
  let curClass = ' ' + el.className + ' ';

  for (let i = 0, j = classes.length; i < j; i++) {
    const clsName = classes[i];
    if (!clsName) continue;

    if (el.classList) {
      el.classList.remove(clsName);
    } else if (hasClass(el, clsName)) {
      curClass = curClass.replace(' ' + clsName + ' ', ' ');
    }
  }
  if (!el.classList) {
    el.className = trim(curClass);
  }
}
/**
      获取当前元素的左上偏移
  * left：最左边的元素到文档左边的距离
  * top：元素顶部到文档顶部的距离
  * right：元素最右边到文档右边的距离
  * bottom：元素底部到文档底部的距离
  * rightIncludeBody：文档最左边的元素到右边的距离
  * bottomIncludeBody：元素底部到文档底部的距离
 *
 * @description:
 */
export function getViewportOffset(element: Element): ViewportOffsetResult {
  const doc = document.documentElement;

  const docScrollLeft = doc.scrollLeft;
  const docScrollTop = doc.scrollTop;
  const docClientLeft = doc.clientLeft;
  const docClientTop = doc.clientTop;

  const pageXOffset = window.pageXOffset;
  const pageYOffset = window.pageYOffset;

  const box = getBoundingClientRect(element);

  const { left: retLeft, top: rectTop, width: rectWidth, height: rectHeight } = box as DOMRect;

  const scrollLeft = (pageXOffset || docScrollLeft) - (docClientLeft || 0);
  const scrollTop = (pageYOffset || docScrollTop) - (docClientTop || 0);
  const offsetLeft = retLeft + pageXOffset;
  const offsetTop = rectTop + pageYOffset;

  const left = offsetLeft - scrollLeft;
  const top = offsetTop - scrollTop;

  const clientWidth = window.document.documentElement.clientWidth;
  const clientHeight = window.document.documentElement.clientHeight;
  return {
    left: left,
    top: top,
    right: clientWidth - rectWidth - left,
    bottom: clientHeight - rectHeight - top,
    rightIncludeBody: clientWidth - left,
    bottomIncludeBody: clientHeight - top,
  };
}

/* istanbul ignore next */
export function on(
  element: Element | HTMLElement | Document | Window,
  event: string,
  handler: EventListenerOrEventListenerObject,
): void {
  if (element && event && handler) {
    element.addEventListener(event, handler, false);
  }
}

/* istanbul ignore next */
export function off(
  element: Element | HTMLElement | Document | Window,
  event: string,
  handler: Fn,
): void {
  if (element && event && handler) {
    element.removeEventListener(event, handler, false);
  }
}