/* Build injects a content-derived version and an explicit public-asset allowlist. */
const CONFIG = JSON.parse("__PWA_CONFIG__");
const PREFIX = "mina-habits-static-";
const CACHE = PREFIX + CONFIG.version;
const ASSETS = new Set(CONFIG.assets);

self.addEventListener("install", event => {
  event.waitUntil((async () => {
    const cache = await caches.open(CACHE);
    // addAll is atomic: a failed download cannot activate a partial release.
    await cache.addAll(CONFIG.assets.map(url => new Request(url, { cache: "reload", credentials: "omit" })));
  })());
});

self.addEventListener("activate", event => {
  event.waitUntil((async () => {
    // A user can accept an update while other windows still hold older code.
    // Preserve their lazy chunks until a later activation with no open windows.
    const windows = await self.clients.matchAll({ type: "window", includeUncontrolled: true });
    if (windows.length === 0) {
      await Promise.all((await caches.keys()).filter(key => key.startsWith(PREFIX) && key !== CACHE).map(key => caches.delete(key)));
    }
    await self.clients.claim();
  })());
});

self.addEventListener("message", event => {
  if (event.data?.type === "ACTIVATE_UPDATE") event.waitUntil(self.skipWaiting());
});

async function cachedAsset(request) {
  const current = await caches.open(CACHE);
  const cached = await current.match(request);
  if (cached) return cached;
  // Old windows can still request fingerprinted chunks after an accepted update.
  for (const key of await caches.keys()) {
    if (key.startsWith(PREFIX) && key !== CACHE) {
      const response = await (await caches.open(key)).match(request);
      if (response) return response;
    }
  }
  return fetch(request);
}

async function navigate(request) {
  const controller = new AbortController();
  const timeout = setTimeout(() => controller.abort(), 4000);
  try {
    const response = await fetch(request, { signal: controller.signal });
    if (response.ok) return response;
  } catch { /* Unreachable server or offline: use the public shell. */ }
  finally { clearTimeout(timeout); }
  return (await (await caches.open(CACHE)).match(CONFIG.shell)) || Response.error();
}

self.addEventListener("fetch", event => {
  const request = event.request;
  const url = new URL(request.url);
  // In particular: no account data, OAuth callbacks, exports, writes or third-party responses.
  if (request.method !== "GET" || url.origin !== self.location.origin || /^\/api(?:\/|$)/.test(url.pathname)) return;
  if (request.mode === "navigate") {
    event.respondWith(navigate(request));
  } else if (ASSETS.has(url.pathname) || /^\/chunk-[\w-]+\.js$/.test(url.pathname)) {
    event.respondWith(cachedAsset(request));
  }
});