// Convenience function to load polyfills and return a promise when it's done.
// If there are no polyfills, then this is just Promise.resolve() which means
// it will execute in the same tick of the event loop (i.e. near-instant).

import { loadIntlPolyfills } from "./intl";

function importBasePolyfills() {
  return import(/* webpackChunkName: "base_polyfills" */ "./base_polyfills");
}

function importExtraPolyfills() {
  return import(/* webpackChunkName: "extra_polyfills" */ "./extra_polyfills");
}

export function loadPolyfills() {
  const needsBasePolyfills = !(
    "toBlob" in HTMLCanvasElement.prototype &&
    "assign" in Object &&
    "values" in Object &&
    "Symbol" in window &&
    "finally" in Promise.prototype
  );

  // Latest version of Firefox and Safari do not have IntersectionObserver.
  // Edge does not have requestIdleCallback.
  // This avoids shipping them all the polyfills.
  /* eslint-disable @typescript-eslint/no-unnecessary-condition -- those properties might not exist in old browsers, even if they are always here in types */
  const needsExtraPolyfills = !(
    window.AbortController &&
    window.IntersectionObserver &&
    window.IntersectionObserverEntry &&
    "isIntersecting" in IntersectionObserverEntry.prototype &&
    window.requestIdleCallback
  );
  /* eslint-enable @typescript-eslint/no-unnecessary-condition */

  return Promise.all([
    loadIntlPolyfills(),
    needsBasePolyfills && importBasePolyfills(),
    needsExtraPolyfills && importExtraPolyfills(),
  ]);
}