import { createHash } from 'node:crypto';

export function shellCachePlugin() {
  return {
    name: 'ridebus-offline-shell',
    generateBundle(_options, bundle) {
      const files = ['/', '/favicon.svg', '/manifest.webmanifest', ...Object.keys(bundle).map(file => '/' + file)];
      const version = createHash('sha256').update(Object.keys(bundle).join('|')).digest('hex').slice(0, 12);
      this.emitFile({ type: 'asset', fileName: 'sw.js', source: `
const CACHE = 'ridebus-board-${version}';
const FILES = ${JSON.stringify(files)};
self.addEventListener('install', event => {
  event.waitUntil(caches.open(CACHE).then(cache => cache.addAll(FILES)));
});
self.addEventListener('activate', event => {
  event.waitUntil(caches.keys().then(keys => Promise.all(keys.filter(key => key.startsWith('ridebus-board-') && key !== CACHE).map(key => caches.delete(key)))).then(() => self.clients.claim()));
});
self.addEventListener('message', event => { if (event.data === 'ACTIVATE') self.skipWaiting(); });
self.addEventListener('fetch', event => {
  const url = new URL(event.request.url);
  if (event.request.method !== 'GET' || url.origin !== self.location.origin || url.pathname.startsWith('/api/') || url.pathname === '/healthz') return;
  if (event.request.mode === 'navigate') {
    event.respondWith(fetch(event.request).catch(() => caches.open(CACHE).then(cache => cache.match('/'))));
  } else if (FILES.includes(url.pathname)) {
    event.respondWith(caches.open(CACHE).then(async cache => (await cache.match(url.pathname)) || fetch(event.request)));
  }
});
` });
    },
  };
}