// Network-first strategy with offline fallback for PWA standalone mode

const CACHE_NAME = "rails-8-starter-offline";
const OFFLINE_URL = "/offline.html";

// Pre-cache the offline fallback page on install
self.addEventListener("install", (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => cache.add(OFFLINE_URL))
  );
  self.skipWaiting();
});

// Clean up old caches on activate
self.addEventListener("activate", (event) => {
  event.waitUntil(
    caches.keys().then((keys) =>
      Promise.all(
        keys
          .filter((key) => key !== CACHE_NAME)
          .map((key) => caches.delete(key))
      )
    )
  );
  self.clients.claim();
});

// Network-first for navigation requests; fallback to offline page on failure
self.addEventListener("fetch", (event) => {
  if (event.request.mode !== "navigate") return;

  const url = new URL(event.request.url);

  event.respondWith(
    fetch(event.request).catch(() =>
      caches.match(OFFLINE_URL).then((cached) => cached || new Response("Offline", { status: 503 }))
    )
  );
});