// projax service worker — Phase 3j install affordance only.
//
// Strategy:
//   * On install: pre-cache /static/style.css + manifest + icons so the
//     standalone shell renders even when offline.
//   * On fetch (GET only): network-first. On network failure, fall back to
//     cache. POSTs, the /mcp/ surface, and everything else go straight to the
//     network so writeback semantics are preserved.
//   * On activate: prune stale caches from earlier versions.
//
// This is NOT full offline mode. It's enough to make the icon work as a
// real PWA + keep static assets warm. Mutations (CalDAV / Gitea writeback)
// still require connectivity.

const CACHE_NAME = 'projax-shell-v1';
const SHELL_ASSETS = [
  '/static/style.css',
  '/static/manifest.webmanifest',
  '/static/icon-192.png',
  '/static/icon-512.png',
  '/static/icon-maskable.png',
];

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

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

self.addEventListener('fetch', (event) => {
  const req = event.request;
  // Only GET — never cache POST/PATCH/DELETE/PUT (writeback + MCP RPC).
  if (req.method !== 'GET') return;
  // Skip MCP RPC entirely — it's stateful JSON-RPC.
  if (new URL(req.url).pathname.startsWith('/mcp/')) return;

  event.respondWith(
    fetch(req)
      .then((res) => {
        // Stash successful GETs into the cache for offline fallback.
        if (res.ok && req.url.startsWith(self.location.origin)) {
          const copy = res.clone();
          caches.open(CACHE_NAME).then((c) => c.put(req, copy));
        }
        return res;
      })
      .catch(() => caches.match(req))
  );
});