/*
 * SiMS POS app-shell cache (S4 deliverable 4). Dead-simple cache-first for
 * same-origin GET so /pos/ still loads when the store-server is down.
 *
 * Deliberate limitations (documented, not bugs):
 *  - The data API is NEVER cached: any /api/* request goes straight to the network
 *    and is allowed to fail when the server is down, so the app's offline queue and
 *    the health-ping drain logic stay in control (a cached /api/health would break
 *    the drain). Only GET is handled; bill POSTs pass through untouched.
 *  - Hashed assets are cached on first fetch (runtime), not precached at build time
 *    — the first load must happen online. The navigation root is best-effort
 *    precached on install.
 *  - Cache-first means a new deploy is picked up only after CACHE is bumped below;
 *    for a counter that values offline resilience over instant updates this is the
 *    right trade, and hashed asset names make stale bundles self-correcting.
 */
const CACHE = 'sims-pos-shell-v1'

self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE).then((c) => c.addAll(['./', './index.html']).catch(() => undefined)),
  )
  self.skipWaiting()
})

self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((keys) => Promise.all(keys.filter((k) => k !== CACHE).map((k) => caches.delete(k)))),
  )
  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
  if (url.pathname.startsWith('/api/')) return // never cache the data/print/health API

  event.respondWith(
    caches.match(req).then((hit) => {
      if (hit !== undefined) return hit
      return fetch(req)
        .then((res) => {
          if (res.ok && res.type === 'basic') {
            const copy = res.clone()
            void caches.open(CACHE).then((c) => c.put(req, copy))
          }
          return res
        })
        .catch(() => hit ?? Response.error())
    }),
  )
})