/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import { Emitter, Event } from '../../base/common/event';
import { IDisposable } from '../../../vs/base/common/lifecycle';

class WindowManager {
  public static readonly INSTANCE = new WindowManager();

  // --- Zoom Level
  private _zoomLevel: number = 0;
  private _lastZoomLevelChangeTime: number = 0;
  private readonly _onDidChangeZoomLevel = new Emitter<number>();

  public readonly onDidChangeZoomLevel: Event<number> =
    this._onDidChangeZoomLevel.event;
  public getZoomLevel(): number {
    return this._zoomLevel;
  }
  public getTimeSinceLastZoomLevelChanged(): number {
    return Date.now() - this._lastZoomLevelChangeTime;
  }

  // --- Zoom Factor
  private _zoomFactor: number = 1;

  public getZoomFactor(): number {
    return this._zoomFactor;
  }

  // --- Pixel Ratio
  public getPixelRatio(): number {
    let ctx: any = document.createElement('canvas').getContext('2d');
    let dpr = window.devicePixelRatio || 1;
    let bsr =
      ctx.webkitBackingStorePixelRatio ||
      ctx.mozBackingStorePixelRatio ||
      ctx.msBackingStorePixelRatio ||
      ctx.oBackingStorePixelRatio ||
      ctx.backingStorePixelRatio ||
      1;
    return dpr / bsr;
  }
}
export function getZoomLevel(): number {
  return WindowManager.INSTANCE.getZoomLevel();
}
/** Returns the time (in ms) since the zoom level was changed */
export function getTimeSinceLastZoomLevelChanged(): number {
  return WindowManager.INSTANCE.getTimeSinceLastZoomLevelChanged();
}
export function onDidChangeZoomLevel(
  callback: (zoomLevel: number) => void
): IDisposable {
  return WindowManager.INSTANCE.onDidChangeZoomLevel(callback);
}

/** The zoom scale for an index, e.g. 1, 1.2, 1.4 */
export function getZoomFactor(): number {
  return WindowManager.INSTANCE.getZoomFactor();
}

export function getPixelRatio(): number {
  return WindowManager.INSTANCE.getPixelRatio();
}

const userAgent = navigator.userAgent;

export const isFirefox = userAgent.indexOf('Firefox') >= 0;
export const isWebKit = userAgent.indexOf('AppleWebKit') >= 0;
export const isChrome = userAgent.indexOf('Chrome') >= 0;
export const isSafari = !isChrome && userAgent.indexOf('Safari') >= 0;
export const isWebkitWebView = !isChrome && !isSafari && isWebKit;
export const isIPad =
  userAgent.indexOf('iPad') >= 0 || (isSafari && navigator.maxTouchPoints > 0);
export const isAndroid = userAgent.indexOf('Android') >= 0;
export const isStandalone =
  window.matchMedia && window.matchMedia('(display-mode: standalone)').matches;