// Puzzle Trainer — Service Worker
const CACHE = "pt-v2";
const SHELL = ["/", "/queens", "/tango", "/zip", "/sudoku", "/patches", "/stats", "/settings"];

self.addEventListener("install", e => {
  e.waitUntil(
    caches.open(CACHE).then(c => c.addAll(SHELL)).then(() => self.skipWaiting())
  );
});

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

self.addEventListener("fetch", e => {
  // Only handle same-origin GET requests
  if (e.request.method !== "GET") return;
  const url = new URL(e.request.url);
  if (url.origin !== self.location.origin) return;

  // Network-first for HTML pages (fresh content), cache-first for assets
  const isPage = e.request.mode === "navigate" || e.request.headers.get("accept")?.includes("text/html");
  const isAsset = url.pathname.startsWith("/_next/static/");

  if (isAsset) {
    // Cache-first for static assets (they're content-hashed)
    e.respondWith(
      caches.match(e.request).then(cached => cached || fetch(e.request).then(res => {
        if (res.ok) caches.open(CACHE).then(c => c.put(e.request, res.clone()));
        return res;
      }))
    );
  } else if (isPage) {
    // Network-first for pages, fallback to cache
    e.respondWith(
      fetch(e.request)
        .then(res => {
          if (res.ok) caches.open(CACHE).then(c => c.put(e.request, res.clone()));
          return res;
        })
        .catch(() => caches.match(e.request).then(cached => cached || caches.match("/")))
    );
  }
});