const CACHE_VERSION = "v6";
const CACHE_PREFIX = "wtr-";
const SHELL_CACHE = `${CACHE_PREFIX}shell-${CACHE_VERSION}`;
const RUNTIME_CACHE = `${CACHE_PREFIX}runtime-${CACHE_VERSION}`;
const API_CACHE = `${CACHE_PREFIX}api-${CACHE_VERSION}`;
const ACTIVE_CACHES = new Set([SHELL_CACHE, RUNTIME_CACHE, API_CACHE]);

const SHELL = [
  "/",
  "/warnings",
  "/hydro",
  "/settings",
  "/offline",
  "/manifest.json",
  "/icons/icon.svg",
  "/icons/maskable.svg",
  "/icons/icon-192.png",
  "/icons/icon-512.png",
  "/icons/maskable-512.png",
];

function isCacheableResponse(response) {
  return response && response.ok && response.type !== "opaque";
}

async function putInCache(cacheName, request, response) {
  if (!isCacheableResponse(response)) return;
  const cache = await caches.open(cacheName);
  await cache.put(request, response.clone());
}

function isWeatherApiRequest(url) {
  return (
    url.pathname.startsWith("/api/imgw/") ||
    url.pathname === "/api/imgw-current" ||
    url.pathname === "/api/current-weather" ||
    url.pathname === "/api/forecast"
  );
}

function isStaticAssetRequest(request, url) {
  return (
    url.origin === self.location.origin &&
    (url.pathname.startsWith("/_next/static/") ||
      url.pathname.startsWith("/icons/") ||
      url.pathname === "/manifest.json" ||
      ["font", "image", "script", "style", "worker"].includes(request.destination))
  );
}

async function cacheFirst(request) {
  const cached = await caches.match(request);
  if (cached) return cached;
  const response = await fetch(request);
  await putInCache(RUNTIME_CACHE, request, response);
  return response;
}

async function networkFirst(request, cacheName) {
  try {
    const response = await fetch(request);
    await putInCache(cacheName, request, response);
    return response;
  } catch {
    return (
      (await caches.match(request)) ||
      new Response(JSON.stringify({ error: "Offline." }), {
        status: 503,
        headers: { "Content-Type": "application/json" },
      })
    );
  }
}

async function handleNavigation(request) {
  try {
    const response = await fetch(request);
    await putInCache(SHELL_CACHE, request, response);
    return response;
  } catch {
    return (await caches.match(request)) || (await caches.match("/")) || (await caches.match("/offline"));
  }
}

self.addEventListener("install", (event) => {
  event.waitUntil(
    caches
      .open(SHELL_CACHE)
      .then((cache) => Promise.allSettled(SHELL.map((url) => cache.add(new Request(url, { cache: "reload" }))))),
  );
  self.skipWaiting();
});

self.addEventListener("activate", (event) => {
  event.waitUntil(
    caches
      .keys()
      .then((keys) =>
        Promise.all(
          keys
            .filter((key) => key.startsWith(CACHE_PREFIX) && !ACTIVE_CACHES.has(key))
            .map((key) => caches.delete(key)),
        ),
      ),
  );
  self.clients.claim();
});

self.addEventListener("fetch", (event) => {
  if (event.request.method !== "GET") return;

  const url = new URL(event.request.url);
  if (url.origin !== self.location.origin) return;

  if (isWeatherApiRequest(url)) {
    event.respondWith(networkFirst(event.request, API_CACHE));
    return;
  }

  if (event.request.mode === "navigate") {
    event.respondWith(handleNavigation(event.request));
    return;
  }

  if (isStaticAssetRequest(event.request, url)) {
    event.respondWith(cacheFirst(event.request));
  }
});

self.addEventListener("push", (event) => {
  const fallbackPayload = {
    title: "IMGW",
    body: "Nowe ostrze\u017cenie meteorologiczne.",
    url: "/warnings",
  };
  let payload = fallbackPayload;
  if (event.data) {
    const text = event.data.text();
    try {
      payload = { ...fallbackPayload, ...JSON.parse(text) };
    } catch {
      payload = { ...fallbackPayload, body: text };
    }
  }

  event.waitUntil(
    self.registration.showNotification(payload.title, {
      body: payload.body,
      icon: "/icons/icon-192.png",
      badge: "/icons/icon-192.png",
      data: { url: payload.url || "/warnings" },
    }),
  );
});

self.addEventListener("notificationclick", (event) => {
  event.notification.close();
  const targetUrl = new URL(event.notification.data?.url || "/warnings", self.location.origin).href;

  event.waitUntil(
    self.clients.matchAll({ type: "window", includeUncontrolled: true }).then((clients) => {
      const existingClient = clients.find((client) => client.url === targetUrl);
      if (existingClient) return existingClient.focus();
      return self.clients.openWindow(targetUrl);
    }),
  );
});