const isPopup = (popupItem, elements) =>
{
  if (!popupItem || !elements)
  {
    return false;
  }

  for (var i = 0, len = elements.length; i < len; i++)
  {
    try
    {
      if (popupItem.contains(elements[i]))
      {
        return true;
      }
      if (elements[i].contains(popupItem))
      {
        return false;
      }
    }
    catch (e)
    {
      return false;
    }
  }

  return false;
};

const validate = (binding) =>
{
  if (typeof binding.value !== 'function')
  {
    console.warn('v-click-outside: provided expression ' + binding.expression + ' is not a function.');
    return false;
  }

  return true;
};



/**
 * resize an element
 */
export default {
  bind(el, binding, vNode)
  {
    if (!validate(binding)) return;

    // Define Handler and cache it on the element
    function handler(e)
    {
      if (!vNode.context) return;

      // some components may have related popup item, on which we shall prevent the click outside event handler.
      var elements = e.path || (e.composedPath && e.composedPath());
      elements && elements.length > 0 && elements.unshift(e.target);

      if (el.contains(e.target) || isPopup(vNode.context.popupItem, elements) || !el.__vueClickOutside__)
      {
        return;
      }

      el.__vueClickOutside__.callback(e);
    }

    // add Event Listeners
    el.__vueClickOutside__ = {
      handler: handler,
      callback: binding.value
    };

    setTimeout(() =>
    {
      document.addEventListener('click', handler);
    }, 200);
  },

  update(el, binding)
  {
    if (validate(binding))
    {
      el.__vueClickOutside__.callback = binding.value;
    }
  },

  unbind(el, binding, vNode)
  {
    document.removeEventListener('click', el.__vueClickOutside__.handler);
    delete el.__vueClickOutside__;
  }
};