chrome/browser/resources/chromeos/audio/page.ts

// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import {getRequiredElement} from 'chrome://resources/js/util.js';

export class Page {
  pageName: string;
  visible: boolean;
  constructor(pageName: string) {
    this.pageName = pageName;
    this.visible = false;
  }

  showPage() {
    this.visible = true;
    getRequiredElement(this.pageName).hidden = false;
  }

  hidePage() {
    this.visible = false;
    getRequiredElement(this.pageName).hidden = true;
  }
}

export class PageNavigator {
  storedPages: Map<string, Page>;
  activePage: Page|null;
  constructor() {
    this.storedPages = new Map();
    this.activePage = null;
  }

  addPage(page: Page) {
    this.storedPages.set(page.pageName, page);
  }

  showPage(pageName: string) {
    if (this.storedPages.has(pageName)) {
      const page: Page = this.storedPages.get(pageName) as Page;
      if (pageName !== this.activePage?.pageName) {
        page.showPage();
        history.pushState({}, '', ('#' + page.pageName));
        this.activePage?.hidePage();
        this.activePage = page;
      }
    }
  }

  static getInstance() {
    if (instance === null) {
      instance = new PageNavigator();
    }
    return instance;
  }
}

let instance: PageNavigator|null = null;