const CACHE_PREFIX = "pi-web";
const CACHE_VERSION = new URL(self.location.href).searchParams.get("v") || "dev";
const STATIC_CACHE = `${CACHE_PREFIX}-static-${CACHE_VERSION}`;
const OFFLINE_URL = "/offline.html";
const PRECACHE_URLS = [
  OFFLINE_URL,
  "/manifest.webmanifest",
  "/icons/icon-192.png",
  "/icons/icon-512.png",
  "/icons/apple-touch-icon.png",
];

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

self.addEventListener("activate", (event) => {
  event.waitUntil(
    caches
      .keys()
      .then((keys) =>
        Promise.all(
          keys
            .filter((key) => key.startsWith(`${CACHE_PREFIX}-`) && key !== STATIC_CACHE)
            .map((key) => caches.delete(key)),
        ),
      )
      .then(() => self.clients.claim()),
  );
});

self.addEventListener("fetch", (event) => {
  const { request } = event;
  if (request.method !== "GET") return;

  const url = new URL(request.url);
  if (url.origin !== self.location.origin) return;

  // Session data and live agent traffic must always come from the local server.
  if (url.pathname.startsWith("/api/") || url.pathname === "/sw.js") return;

  if (request.mode === "navigate") {
    event.respondWith(
      fetch(request).catch(async () => {
        const fallback = await caches.match(OFFLINE_URL);
        return fallback ?? Response.error();
      }),
    );
    return;
  }

  const isStaticAsset =
    url.pathname.startsWith("/_next/static/") ||
    PRECACHE_URLS.includes(url.pathname);

  if (isStaticAsset) {
    event.respondWith(cacheFirst(request));
  }
});

async function cacheFirst(request) {
  const cached = await caches.match(request);
  if (cached) return cached;

  const response = await fetch(request);
  if (response.ok && response.type === "basic") {
    const cache = await caches.open(STATIC_CACHE);
    await cache.put(request, response.clone());
  }
  return response;
}