import { globalThis, document } from './server-safe-globals.js';
import { delay } from './utils.js';
import { isFullscreenEnabled } from './fullscreen-api.js';

/**
 * Test element
 */
let testMediaEl: HTMLVideoElement;
export const getTestMediaEl = (): HTMLVideoElement => {
  if (testMediaEl) return testMediaEl;
  testMediaEl = document?.createElement?.('video');
  return testMediaEl;
};

/**
 * Test for volume support
 *
 * @param mediaEl - The media element to test
 */
export const hasVolumeSupportAsync = async (
  mediaEl: HTMLVideoElement = getTestMediaEl()
): Promise<boolean> => {
  if (!mediaEl) return false;
  const prevVolume = mediaEl.volume;
  mediaEl.volume = prevVolume / 2 + 0.1;
  // Remove event listeners later via an abort controller.
  const abortController = new AbortController();
  const volumeSupported = await Promise.race([
    dispatchedVolumeChange(mediaEl, abortController.signal),
    volumeChanged(mediaEl, prevVolume),
  ]);
  abortController.abort();
  return volumeSupported;
};

const dispatchedVolumeChange = (mediaEl: HTMLVideoElement, signal: AbortSignal) => {
  // If the volumechange event is dispatched, it means the volume property is supported.
  return new Promise<boolean>((resolve) => {
    mediaEl.addEventListener('volumechange', () => resolve(true), { signal });
  });
};

const volumeChanged = async (mediaEl: HTMLVideoElement, prevVolume: number) => {
  // iOS Safari doesn't allow setting volume programmatically but it will
  // change the volume property for a short time before reverting.
  // On heavy sites this can take a while to revert so we need to wait at least
  // 100ms to make sure the volume has not changed.
  // If there is no change sooner, return false early to minimize UI jank.
  for (let i = 0; i < 10; i++) {
    if (mediaEl.volume === prevVolume) return false;
    await delay(10);
  }
  return mediaEl.volume !== prevVolume;
};

// let volumeSupported;
// export const volumeSupportPromise = hasVolumeSupportAsync().then((supported) => {
//   volumeSupported = supported;
//   return volumeSupported;
// });

// NOTE: This also matches at least some non-Safari UAs on e.g. iOS, such as Chrome, perhaps since
// these browsers are built on top of the OS-level WebKit browser, so use accordingly (CJP).
// See, e.g.: https://www.whatismybrowser.com/guides/the-latest-user-agent/chrome
const isSafari: boolean = /.*Version\/.*Safari\/.*/.test(
  globalThis.navigator.userAgent
);
/**
 * Test for PIP support
 *
 * @param mediaEl - The media element to test
 */
export const hasPipSupport = (
  mediaEl: HTMLVideoElement = getTestMediaEl()
): boolean => {
  // NOTE: PWAs for Apple that rely on Safari don't support picture in picture but still have `requestPictureInPicture()`
  // (which will result in a failed promise). Checking for those conditions here (CJP).
  // This should still work for macOS PWAs installed using Chrome, where PiP is supported.
  if (globalThis.matchMedia('(display-mode: standalone)').matches && isSafari)
    return false;
  return typeof mediaEl?.requestPictureInPicture === 'function';
};

/**
 * Test for Fullscreen support
 *
 * @param mediaEl - The media element to test
 */
export const hasFullscreenSupport = (mediaEl = getTestMediaEl()) => {
  return isFullscreenEnabled({ documentElement: document, media: mediaEl });
};

export const fullscreenSupported: boolean = hasFullscreenSupport();
export const pipSupported: boolean = hasPipSupport();
export const airplaySupported: boolean =
  !!globalThis.WebKitPlaybackTargetAvailabilityEvent;
export const castSupported: boolean = !!globalThis.chrome;