Commilitia-Drop/web/public/sw.js

// 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;
        }),
    );
});

// ---- Web Push --------------------------------------------------------------
// Fires only when this device's page is closed (an open page got the event over
// SSE and showed an in-app toast instead). The payload is the JSON the server's
// push.Sender already localized: { type, title, body, tag, url }. The SW just
// displays it — no /api access, no app logic.
self.addEventListener("push", (event) =>
{
    let data = {};
    try { data = event.data ? event.data.json() : {}; }
    catch (_e) { data = {}; }

    const title = data.title || "cdrop";
    const options = {
        body: data.body || "",
        tag: data.tag || undefined,        // same tag replaces a stale notification in place
        icon: "/icon-192.png",
        badge: "/icon-192.png",
        data: { url: data.url || "/" },
    };
    event.waitUntil(self.registration.showNotification(title, options));
});

// Clicking a notification focuses an existing window if one is open, else opens
// the app at the notification's target URL.
self.addEventListener("notificationclick", (event) =>
{
    event.notification.close();
    const target = (event.notification.data && event.notification.data.url) || "/";
    event.waitUntil(
        self.clients.matchAll({ type: "window", includeUncontrolled: true }).then((clients) =>
        {
            for (const c of clients)
            {
                if ("focus" in c) { return c.focus(); }
            }
            return self.clients.openWindow ? self.clients.openWindow(target) : undefined;
        }),
    );
});