malice

import { writable } from 'svelte/store';

import { mayAutoReload } from './engine-build';

const ENGINE_RELOAD_GUARD = 'malice-engine-reload';

export const engineStale = writable(false);

export const engineRecovered = writable(0);

let release: () => Promise<void> = () => Promise.resolve();

export function setEngineRelease(fn: () => Promise<void>): void {

  release = fn;

}

export function releaseEngine(): Promise<void> {

  return release();

}

function reloadWhenHidden(): void {

  if (document.visibilityState !== 'hidden') return;

  const last = Number(sessionStorage.getItem(ENGINE_RELOAD_GUARD)) || null;

  const now = Date.now();

  if (!mayAutoReload(now, last)) return;

  sessionStorage.setItem(ENGINE_RELOAD_GUARD, String(now));

  void releaseEngine().then(() => window.location.reload());

}

/**

 * Tabs in a handover leave the reload to the service worker activation. A hidden tab reloading

 * ahead of it lands on the new build under the old service worker and gets reloaded again.

 */

export function markEngineStale(autoReload = true): void {

  engineStale.set(true);

  if (!autoReload) return;

  document.addEventListener('visibilitychange', reloadWhenHidden);

  reloadWhenHidden();

}