/* Prabhupāda Says — Web Push service worker.
 *
 * Handles incoming push messages (shows a notification) and clicks (focuses
 * an existing same-origin tab and navigates it, or opens a new one). The push
 * payload is the JSON the BFF sends:
 *   { title, body, url, icon, tag, require_interaction }
 */

// --- Offline caching (Save-offline feature) ---------------------------------
// Bump CACHE_VERSION to invalidate old asset/page caches on the next activate.
const CACHE_VERSION = "v1";
const PAGES_CACHE = `offline-pages-${CACHE_VERSION}`; // saved page HTML documents
const ASSETS_CACHE = `offline-assets-${CACHE_VERSION}`; // /_next/* + static files
const OFFLINE_CACHES = [PAGES_CACHE, ASSETS_CACHE];
// The library page doubles as the navigation fallback when offline.
const OFFLINE_FALLBACK = "/downloads";

self.addEventListener("install", () => self.skipWaiting());
self.addEventListener("activate", (event) =>
  event.waitUntil(
    (async () => {
      // Drop stale offline caches from previous CACHE_VERSIONs.
      const names = await caches.keys();
      await Promise.all(
        names
          .filter(
            (n) => n.startsWith("offline-") && !OFFLINE_CACHES.includes(n),
          )
          .map((n) => caches.delete(n)),
      );
      await self.clients.claim();
    })(),
  ),
);

// Treat content-hashed Next assets and static files as immutable → cache-first.
function isCacheableAsset(url) {
  if (url.origin !== self.location.origin) return false;
  if (url.pathname.startsWith("/_next/")) return true;
  return /\.(?:js|css|woff2?|ttf|otf|png|jpe?g|webp|avif|svg|ico|gif)$/.test(
    url.pathname,
  );
}

self.addEventListener("fetch", (event) => {
  const req = event.request;
  if (req.method !== "GET") return; // never touch POSTs (push subscribe etc.)

  const url = new URL(req.url);

  // 1. Page navigations.
  //    ONLINE: do NOT intercept — let the browser navigate natively. Proxying
  //    a redirected response (the app server-`redirect()`s every book chapter
  //    index to its first verse) or Next's streamed SSR through the SW makes
  //    iOS/WebKit standalone PWAs render a blank page. Native handling is
  //    identical to how the app behaved before this SW had a fetch handler.
  //    OFFLINE: serve a saved copy, then the offline library, then a stub —
  //    all plain stored/constructed Responses, which WebKit accepts.
  if (req.mode === "navigate") {
    if (self.navigator.onLine) return;
    event.respondWith(
      (async () => {
        const pages = await caches.open(PAGES_CACHE);
        const saved =
          (await pages.match(req.url)) || (await pages.match(url.pathname));
        if (saved) return saved;
        const fallback = await pages.match(OFFLINE_FALLBACK);
        if (fallback) return fallback;
        return new Response(
          "<!doctype html><meta charset=utf-8><title>Offline</title><body style=\"font-family:system-ui;padding:2rem\"><h1>You're offline</h1><p>This page hasn't been saved for offline use.</p>",
          { headers: { "Content-Type": "text/html; charset=utf-8" }, status: 503 },
        );
      })(),
    );
    return;
  }

  // 2. Immutable same-origin assets: cache-first so the app shell boots offline.
  if (isCacheableAsset(url)) {
    event.respondWith(
      (async () => {
        const cache = await caches.open(ASSETS_CACHE);
        const hit = await cache.match(req);
        if (hit) return hit;
        const res = await fetch(req);
        // Only cache full, same-origin 200s. Guard put() so a 206/opaque/quota
        // rejection can never fail the request (which could drop a JS chunk).
        try {
          if (res && res.status === 200 && res.type === "basic") {
            await cache.put(req, res.clone());
          }
        } catch {
          /* serve the response uncached */
        }
        return res;
      })(),
    );
    return;
  }

  // 3. Everything else (BFF data, RSC, /api): straight to network.
});

// The page registers us as /sw.js?bff=<origin> so subscription management
// works without a client tab open (the auth cookie rides on
// credentials:"include"). Same-origin deployments fall back to our origin.
const BFF_BASE =
  new URL(self.location.href).searchParams.get("bff") || self.location.origin;

/* Push services rotate subscriptions (expiry, key migration). Without this
 * handler the server keeps pushing to the dead endpoint and the user silently
 * stops getting notifications — so re-subscribe with the same application
 * server key and swap the registration on the BFF. */
self.addEventListener("pushsubscriptionchange", (event) => {
  event.waitUntil(
    (async () => {
      const old = event.oldSubscription;
      let sub = event.newSubscription || null;
      if (!sub) {
        const appKey = old && old.options && old.options.applicationServerKey;
        if (!appKey) return; // nothing to re-subscribe with
        sub = await self.registration.pushManager.subscribe({
          userVisibleOnly: true,
          applicationServerKey: appKey,
        });
      }

      const json = sub.toJSON();
      await fetch(`${BFF_BASE}/api/v1/push/subscribe`, {
        method: "POST",
        credentials: "include",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ endpoint: json.endpoint, keys: json.keys }),
      });
      if (old && old.endpoint && old.endpoint !== sub.endpoint) {
        await fetch(`${BFF_BASE}/api/v1/push/unsubscribe`, {
          method: "POST",
          credentials: "include",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({ endpoint: old.endpoint }),
        }).catch(() => {
          /* best-effort — the server prunes dead endpoints on send anyway */
        });
      }
    })(),
  );
});

self.addEventListener("push", (event) => {
  event.waitUntil(
    (async () => {
      let data = {};
      if (event.data) {
        try {
          // event.data.json() is synchronous; text() is a Promise — only
          // awaited in the fallback.
          data = event.data.json();
        } catch {
          data = { body: await event.data.text() };
        }
      }

      const title = data.title || "Prabhupāda Says";
      const options = {
        body: data.body || "",
        icon: data.icon || "/icon-192.png",
        badge: "/icon-192.png",
        // A tag dedupes a series (e.g. daily reminders replace the previous
        // one); renotify re-alerts when a tagged notification is replaced.
        tag: data.tag || undefined,
        renotify: !!data.tag,
        // Reminders set this so they stay until acted on (desktop otherwise
        // auto-dismisses). Defaults off for everything else.
        requireInteraction: data.require_interaction === true,
        vibrate: [100, 50, 100],
        data: { url: data.url || "/" },
        actions: [{ action: "open", title: "Open" }],
      };
      await self.registration.showNotification(title, options);
    })(),
  );
});

self.addEventListener("notificationclick", (event) => {
  event.notification.close();
  // The only action is "open"; the default body click behaves the same.
  const url = (event.notification.data && event.notification.data.url) || "/";
  const target = new URL(url, self.location.origin).href;

  event.waitUntil(
    (async () => {
      const list = await self.clients.matchAll({
        type: "window",
        includeUncontrolled: true,
      });
      // Reuse a single existing same-origin tab — focus it and navigate only
      // that one (not every matched window).
      for (const client of list) {
        if (client.url.startsWith(self.location.origin)) {
          await client.focus();
          if ("navigate" in client) {
            try {
              await client.navigate(target);
            } catch {
              /* cross-document navigation can reject; focus already happened */
            }
          }
          return;
        }
      }
      if (self.clients.openWindow) await self.clients.openWindow(target);
    })(),
  );
});