// STEM Copilot — Service Worker (PWA installability + basic cache)
const CACHE_NAME = 'stemcopilot-v2';
const SHELL_URLS = [
  '/',
  '/static/style.css',
  '/static/app.js',
  '/assets/bot.png',
  '/assets/stem_black.png',
  '/assets/stembotix.png',
];

self.addEventListener('install', (e) => {
  e.waitUntil(
    caches.open(CACHE_NAME).then((cache) => cache.addAll(SHELL_URLS))
  );
  self.skipWaiting();
});

self.addEventListener('activate', (e) => {
  e.waitUntil(
    caches.keys().then((keys) =>
      Promise.all(keys.filter((k) => k !== CACHE_NAME).map((k) => caches.delete(k)))
    )
  );
  self.clients.claim();
});

self.addEventListener('fetch', (e) => {
  // Network-first for API calls, cache-first for shell assets
  if (e.request.url.includes('/chat') || e.request.url.includes('/auth') ||
      e.request.url.includes('/threads') || e.request.url.includes('/history') ||
      e.request.url.includes('/user') || e.request.url.includes('/export') ||
      e.request.url.includes('/health')) {
    return; // Let these go straight to network
  }
  e.respondWith(
    caches.match(e.request).then((cached) => cached || fetch(e.request))
  );
});