export function hasClass (el, cls) {
  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, cls) {
  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, cls) {
  let i = 0;
  let j;
  let clsName;
  if (!el || !cls) return;
  const classes = cls.split(' ');
  let curClass = ' ' + el.className + ' ';
  for (i, j = classes.length; i < j; i++) {
    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 = curClass;
  }
};
