sw.js

/* ─────────────────────────────────────────────
   RRPL Remote Arm — Service Worker (PWA)
   ───────────────────────────────────────────── */

'use strict';

const CACHE_NAME = 'rrpl-remote-arm-v2';

// All local assets to pre-cache on install
const LOCAL_ASSETS = [
  './',
  './index.html',
  './styles.css',
  './app.js',
  './manifest.json',
];

// ── Install: pre-cache local assets ──────────
self.addEventListener('install', event => {
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then(cache => cache.addAll(LOCAL_ASSETS))
      .then(() => self.skipWaiting())
  );
});

// ── Activate: purge old caches ────────────────
self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys()
      .then(keys =>
        Promise.all(
          keys
            .filter(key => key !== CACHE_NAME)
            .map(key => caches.delete(key))
        )
      )
      .then(() => self.clients.claim())
  );
});

// ── Fetch: cache-first for local, network-first
//          for Google Fonts (so updates land) ──
self.addEventListener('fetch', event => {
  const url = new URL(event.request.url);

  // Google Fonts — stale-while-revalidate
  if (url.hostname === 'fonts.googleapis.com' || url.hostname === 'fonts.gstatic.com') {
    event.respondWith(staleWhileRevalidate(event.request));
    return;
  }

  // Everything else — cache-first with network fallback
  event.respondWith(cacheFirst(event.request));
});

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

  try {
    const response = await fetch(request);
    if (response.ok) {
      const cache = await caches.open(CACHE_NAME);
      cache.put(request, response.clone());
    }
    return response;
  } catch {
    // Offline and not cached — return a minimal offline page for navigations
    if (request.mode === 'navigate') {
      return caches.match('./index.html');
    }
    return new Response('Offline', { status: 503 });
  }
}

async function staleWhileRevalidate(request) {
  const cache  = await caches.open(CACHE_NAME);
  const cached = await cache.match(request);

  const networkFetch = fetch(request)
    .then(response => {
      if (response.ok) cache.put(request, response.clone());
      return response;
    })
    .catch(() => null);

  return cached || networkFetch;
}