import { Capacitor } from '@capacitor/core';

let started = false;

/**
 * Register the app-shell service worker on the web only.
 *
 * The same worker also handles Web Push, so registering it unconditionally does
 * not conflict with the push opt-in path. Native Capacitor uses its local asset
 * server instead — a service worker there would only add a second cache.
 */
export function registerAppServiceWorker(): void {
  if (started || typeof window === 'undefined' || !('serviceWorker' in navigator)) return;
  if (Capacitor.isNativePlatform()) {
    // The native shell must never inherit an old web app-shell worker. Some
    // Android WebViews expose a partial/absent Service Worker API, so every
    // call is feature-checked and wrapped — this cleanup must never abort React
    // boot (that produced a black screen after the native splash).
    try {
      if (navigator.serviceWorker && typeof navigator.serviceWorker.getRegistrations === 'function') {
        void navigator.serviceWorker.getRegistrations()
          .then((regs) => regs.forEach((reg) => { try { reg.unregister(); } catch { /* ignore */ } }))
          .catch(() => undefined);
      }
      if (typeof caches !== 'undefined' && typeof caches.keys === 'function') {
        void caches.keys()
          .then((keys) => keys.filter((key) => key.startsWith('skate-spots-shell-'))
            .forEach((key) => { void caches.delete(key).catch(() => undefined); }))
          .catch(() => undefined);
      }
    } catch {
      // Best-effort only; boot must continue.
    }
    return;
  }
  started = true;

  const register = () => {
    navigator.serviceWorker.register('/push-sw.js', { updateViaCache: 'none' }).catch(() => {
      // Private mode / unsupported browser — the app works without it.
    });
  };

  if (document.readyState === 'complete') register();
  else window.addEventListener('load', register, { once: true });
}