import { Utility } from '../../core/utility';
import './asidenav.scss';

const FAVORITES_BTN_CLASS = 'navbar__list-item--favorite';
const FAVORITES_BTN_ACTIVE_CLASS = 'navbar__list-item--active';
const ASIDENAV_INITIALIZED_CLASS = 'asidenav--initialized';
const ASIDENAV_EXPANDED_CLASS = 'main__aside--expanded';
const ASIDENAV_LIST_ITEM_CLASS = 'asidenav__list-item';
const ASIDENAV_SUBMENU_CLASS = 'asidenav__nested-list-wrapper';

@Utility({
  selector: '[uw-asidenav]',
})
export class Asidenav {

  _element;
  _asidenavSubmenus;

  constructor(element) {
    if (!element) {
      throw new Error('Asidenav utility cannot be setup without an element!');
    }

    this._element = element;

    if (this._element.classList.contains(ASIDENAV_INITIALIZED_CLASS)) {
      return false;
    }

    this._initFavoritesButton();
    this._initAsidenavSubmenus();

    // mark initialized
    this._element.classList.add(ASIDENAV_INITIALIZED_CLASS);
  }

  destroy() {
    this._asidenavSubmenus.forEach((union) => {
      union.listItem.removeEventListener(union.hoverHandler);
    });
  }

  _initFavoritesButton() {
    const favoritesBtn = document.querySelector('.' + FAVORITES_BTN_CLASS);
    if (favoritesBtn) {
      favoritesBtn.addEventListener('click', (event) => {
        favoritesBtn.classList.toggle(FAVORITES_BTN_ACTIVE_CLASS);
        this._element.classList.toggle(ASIDENAV_EXPANDED_CLASS);
        event.preventDefault();
      }, true);
    }
  }

  _initAsidenavSubmenus() {
    this._asidenavSubmenus = Array.from(this._element.querySelectorAll('.' + ASIDENAV_LIST_ITEM_CLASS))
      .map(function(listItem) {
        const submenu = listItem.querySelector('.' + ASIDENAV_SUBMENU_CLASS);
        return { listItem, submenu };
      }).filter(function(union) {
        return union.submenu !== null;
      });

    this._asidenavSubmenus.forEach((union) => {
      union.hoverHandler = this._createMouseoverHandler(union);
      union.listItem.addEventListener('mouseover', union.hoverHandler);
    });
  }

  _createMouseoverHandler(union) {
    return () => {
      const rectListItem = union.listItem.getBoundingClientRect();
      const rectSubMenu = union.submenu.getBoundingClientRect();

      union.submenu.style.left = (rectListItem.left + rectListItem.width) + 'px';
      if (window.innerHeight - rectListItem.top < rectSubMenu.height) {
        union.submenu.style.top = (rectListItem.top + rectListItem.height - rectSubMenu.height) + 'px';
      } else {
        union.submenu.style.top = rectListItem.top + 'px';
      }
    };
  }
}