// cdrop service worker — makes the web app installable and caches hashed static
// assets for faster repeat loads.
//
// Deliberately minimal. It does NOT intercept:
//   - /api/*        — SSE (/api/hub/events), clipboard, signaling, relay need a
//                     live, unbuffered connection; and the OAuth exchange/refresh
//                     must not be cached.
//   - navigations   — page loads / OAuth redirects go straight to the network.
//                     (A SW that mediates navigations was stalling the Casdoor →
//                     app redirect for ~2 min in Safari; cdrop is useless offline
//                     anyway, so there's nothing to gain by caching the shell.)
//   - cross-origin  — fonts / CDN are left to the browser.
//
// What's left: hashed JS/CSS/image assets, served stale-while-revalidate.

const CACHE = "cdrop-assets-v2";

self.addEventListener("install", (event) =>
{
    // No precache — assets are cached lazily on first fetch. Activate immediately.
    event.waitUntil(self.skipWaiting());
});

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

self.addEventListener("fetch", (event) =>
{
    const req = event.request;
    if (req.method !== "GET") { return; }
    if (req.mode === "navigate") { return; }                 // page loads / OAuth redirects → network

    const url = new URL(req.url);
    if (url.origin !== self.location.origin) { return; }      // cross-origin (fonts/CDN) → browser default
    if (url.pathname.startsWith("/api/")) { return; }         // live backend → never intercept

    // Static assets (Vite emits content-hashed, immutable files): serve cache
    // immediately, refresh in the background.
    event.respondWith(
        caches.match(req).then((cached) =>
        {
            const network = fetch(req)
                .then((resp) =>
                {
                    if (resp && resp.status === 200 && resp.type === "basic")
                    {
                        const copy = resp.clone();
                        caches.open(CACHE).then((c) => c.put(req, copy)).catch(() => {});
                    }
                    return resp;
                })
                .catch(() => cached);
            return cached || network;
        }),
    );
});