export interface NavItem {
  id: string;
  href: string;
  label: string;
  subitems?: Array<NavItem>;
  parent?: string;
}

export interface LandmarkItem {
  href?: string;
  label?: string;
  type?: string;
}

export default class Navigation {
  constructor(xml: XMLDocument);

  toc: Array<NavItem>;
  landmarks: Array<LandmarkItem>;

  parse(xml: XMLDocument): void;
  get(target: string): NavItem;
  landmark(type: string): LandmarkItem;
  load(json: string): Array<NavItem>;
  forEach(fn: (item: NavItem) => {}): any;

  private unpack(toc: Array<NavItem>): void;
  private parseNav(navHtml: XMLDocument): Array<NavItem>;
  private navItem(item: Element): NavItem;
  private parseLandmarks(navHtml: XMLDocument): Array<LandmarkItem>;
  private landmarkItem(item: Element): LandmarkItem;
  private parseNcx(navHtml: XMLDocument): Array<NavItem>;
  private ncxItem(item: Element): NavItem;
  private getByIndex(
    target: string,
    index: number,
    navItems: NavItem[]
  ): NavItem;
}