/* dsh-sync service worker: offline app shell + last-known API responses.
 * Served at /sw.js (scope /). Registration only happens in secure contexts;
 * plain-HTTP LAN deployments simply skip it and behave as before.
 */
"use strict";
const SHELL_CACHE = "dsh-shell-v1";
const API_CACHE = "dsh-api-v1";

self.addEventListener("install", (e) => {
  e.waitUntil(
    caches.open(SHELL_CACHE)
      .then((c) => c.addAll(["/app"]))
      .then(() => self.skipWaiting())
  );
});

self.addEventListener("activate", (e) => {
  e.waitUntil((async () => {
    for (const k of await caches.keys()) {
      if (k !== SHELL_CACHE && k !== API_CACHE) await caches.delete(k);
    }
    await self.clients.claim();
  })());
});

self.addEventListener("fetch", (e) => {
  const req = e.request;
  if (req.method !== "GET") return;
  const url = new URL(req.url);
  if (url.origin !== self.location.origin) return;

  if (req.mode === "navigate") {
    // App shell: fresh when online, cached copy when the server is unreachable.
    e.respondWith((async () => {
      try {
        const resp = await fetch(req);
        if (resp.ok) (await caches.open(SHELL_CACHE)).put("/app", resp.clone());
        return resp;
      } catch {
        return (await caches.match("/app")) || Response.error();
      }
    })());
    return;
  }

  if (url.pathname.startsWith("/v1/")) {
    // API: network-first, fall back to the last successful response.
    e.respondWith((async () => {
      try {
        const resp = await fetch(req);
        if (resp.ok) (await caches.open(API_CACHE)).put(req, resp.clone());
        return resp;
      } catch {
        const hit = await caches.match(req);
        if (hit) return hit;
        return new Response(JSON.stringify({ detail: "offline" }), {
          status: 503,
          headers: { "Content-Type": "application/json" },
        });
      }
    })());
  }
});