const CACHE_NAME = "woordjes-v2";
const OFFLINE_URLS = [
    "/learn.php",
    "/manifest.json",
    "/assets/css/style.css",
    "/assets/js/db.js",
    "/assets/js/offline-engine.js",
    "/assets/js/sync.js"
];

/**
 * INSTALL
 * Cache basis assets voor offline gebruik
 */
self.addEventListener("install", (event) => {
    event.waitUntil(
        caches.open(CACHE_NAME).then((cache) => {
            return cache.addAll(OFFLINE_URLS);
        })
    );

    self.skipWaiting();
});

/**
 * ACTIVATE
 * Oude caches opruimen
 */
self.addEventListener("activate", (event) => {
    event.waitUntil(
        caches.keys().then((keys) => {
            return Promise.all(
                keys.map((key) => {
                    if (key !== CACHE_NAME) {
                        return caches.delete(key);
                    }
                })
            );
        })
    );

    self.clients.claim();
});

/**
 * FETCH STRATEGY
 * - HTML/CSS/JS → cache-first
 * - API → nooit cachen (offline engine regelt dit)
 */
self.addEventListener("fetch", (event) => {

    const url = new URL(event.request.url);

    // API NIET cachen
    if (url.pathname.startsWith("/api/")) {
        return;
    }

    event.respondWith(
        caches.match(event.request).then((cached) => {

            if (cached) {
                return cached;
            }

            return fetch(event.request).then((response) => {

                const copy = response.clone();

                caches.open(CACHE_NAME).then((cache) => {
                    cache.put(event.request, copy);
                });

                return response;
            });
        })
    );
});