// Bumped to v4. The v3 worker cached /_next/static/ and /assets/ cache-first
// under a hardcoded cache name that was not tied to the build, so a release
// left the browser replaying the previous release's chunks against the new
// HTML. That combination renders a blank page. The cache name is the version,
// so it must move whenever this behaviour changes.
const CACHE = "atom-v4";
const API_CACHE = "atom-api-v4";

self.addEventListener("install", () => self.skipWaiting());

self.addEventListener("activate", (event) => {
	event.waitUntil(
		caches
			.keys()
			.then((keys) =>
				Promise.all(
					keys
						.filter((k) => k !== CACHE && k !== API_CACHE)
						.map((k) => caches.delete(k)),
				),
			)
			.then(() => self.clients.claim()),
	);
});

// Static build output is NOT cached here on purpose.
//
// nginx already sends `/_next/static/` and `/assets/` with
// `max-age=31536000, immutable`. Those filenames are content-hashed, so the
// HTTP cache is both sufficient and safe: a changed file gets a new name.
// Wrapping them in a Cache Storage entry bought nothing and introduced a
// staleness bug the HTTP cache cannot have — the cache name had no build id,
// so a release kept serving the previous release's chunks.
//
// Letting these requests fall through also means a failed fetch surfaces as a
// normal network error the browser can retry, instead of a rejected
// respondWith() that silently drops the <script> and leaves React unhydrated.
const isStaticBuildOutput = (pathname) =>
	pathname.startsWith("/assets/") ||
	pathname.startsWith("/_next/static/") ||
	pathname.startsWith("/_next/data/");

self.addEventListener("fetch", (event) => {
	const req = event.request;
	if (req.method !== "GET") return;
	const url = new URL(req.url);
	if (url.origin !== self.location.origin) return;
	if (isStaticBuildOutput(url.pathname)) return;

	// Offline tolerance for the few endpoints the public shell needs to render
	// at all. Network-first, so a deploy is never shadowed by this cache.
	if (
		url.pathname.startsWith("/api/home") ||
		url.pathname.startsWith("/api/online") ||
		url.pathname.startsWith("/api/radio/config")
	) {
		event.respondWith(
			caches.open(API_CACHE).then((cache) =>
				fetch(req)
					.then((res) => {
						if (res.ok) cache.put(req, res.clone());
						return res;
					})
					.catch(() => cache.match(req)),
			),
		);
		return;
	}

	// Admin pages are never cached (nginx sends no-store once a session cookie
	// is present). Always network-first; offline is the browser's call.
	if (req.mode === "navigate") {
		event.respondWith(fetch(req));
	}
});