// cdrop service worker — makes the web app installable and caches the static
// shell for instant launch.
//
// HARD RULE: it MUST NOT intercept /api/* . The SSE stream (/api/hub/events),
// clipboard, WebRTC signaling and relay all need a live, unbuffered network
// connection — those requests are passed straight through to the network. Same
// goes for cross-origin requests (fonts / CDN): the browser handles them.
//
// cdrop is useless offline (everything needs the backend), so this is a shell
// cache for fast loads + installability, not a real offline app.

const CACHE = "cdrop-shell-v1";
const SHELL = [
    "/",
    "/site.webmanifest",
    "/favicon-96.png",
    "/icon-192.png",
    "/apple-touch-icon-180.png",
    "/logo-mark.png",
];

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

    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

    // SPA navigations: network-first so a new deploy serves fresh HTML (which
    // points at the new hashed assets); fall back to the cached shell offline.
    if (req.mode === "navigate")
    {
        event.respondWith(
            fetch(req)
                .then((resp) =>
                {
                    const copy = resp.clone();
                    caches.open(CACHE).then((c) => c.put("/", copy)).catch(() => {});
                    return resp;
                })
                .catch(() => caches.match("/").then((r) => r || Response.error())),
        );
        return;
    }

    // Static assets (hashed JS/CSS/images are immutable): stale-while-revalidate.
    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;
        }),
    );
});