enbock / Application-Router

export default class Router {

  currentPage: Observer<PageData | null>;

  history: History;

  constructor(pageObserver: Observer<PageData | null>, history: History) {

    this.currentPage = pageObserver;

    this.history = history;

  }

  attachTo(window: Window) {

    window.addEventListener('popstate', this.onHistoryChange.bind(this));

  }

  initialize(): void {

    if (this.currentPage.value == null) return;

    const firstPage: PageData = this.currentPage.value;

    this.history.replaceState(firstPage, firstPage.name, firstPage.baseUrl);

    this.updatePage(firstPage);

  }

  changePage(newPage: PageData): void {

    const currentPage: PageData | null = this.currentPage.value;

    if (currentPage != null && currentPage.name == newPage.name) {

      return;

    }

    this.history.replaceState(newPage, newPage.name, newPage.currentUrl);

    this.updatePage(newPage);

  }

  protected updatePage(page: PageData): void {

    this.currentPage.value = page;

  }

  protected onHistoryChange(event: PopStateEvent): void {

    const newPage: PageData = event.state as PageData;

    this.updatePage(newPage);