// Service Worker — parent-portal PWA 离线缓存
// 依据：01-understanding.md §18.4 Service Worker 策略
// 缓存策略：
//   静态资源 → Cache First + 网络更新（TTL 24h）
//   子女列表 → Stale While Revalidate（TTL 5min）
//   子女成绩 → Network First，失败回退缓存（TTL 30s）
//   通知/偏好 → Network Only
//   API 401 → 不缓存

const CACHE_VERSION = "parent-portal-v1";
const STATIC_CACHE = `${CACHE_VERSION}-static`;
const DATA_CACHE = `${CACHE_VERSION}-data`;

const STATIC_ASSETS = [
  "/",
  "/parent/dashboard",
  "/login",
  "/manifest.json",
];

// 安装：预缓存静态资源
self.addEventListener("install", (event) => {
  event.waitUntil(
    caches.open(STATIC_CACHE).then((cache) => cache.addAll(STATIC_ASSETS)).then(() => self.skipWaiting())
  );
});

// 激活：清理旧缓存
self.addEventListener("activate", (event) => {
  event.waitUntil(
    caches.keys().then((keys) =>
      Promise.all(
        keys
          .filter((key) => !key.startsWith(CACHE_VERSION))
          .map((key) => caches.delete(key))
      )
    ).then(() => self.clients.claim())
  );
});

// 请求拦截：按资源类型选择缓存策略
self.addEventListener("fetch", (event) => {
  const { request } = event;
  const url = new URL(request.url);

  // 仅处理同源请求
  if (url.origin !== self.location.origin) return;

  // 非 GET 请求直接透传
  if (request.method !== "GET") return;

  // API 请求：Network First（数据类）或 Network Only（通知/偏好）
  if (url.pathname.startsWith("/api/")) {
    // 通知和偏好设置不缓存
    if (url.pathname.includes("/notifications") || url.pathname.includes("/preferences")) {
      return;
    }
    // GraphQL 和其他 API：Network First + 回退缓存
    event.respondWith(
      fetch(request)
        .then((response) => {
          if (response.ok && response.status !== 401) {
            const clone = response.clone();
            caches.open(DATA_CACHE).then((cache) => cache.put(request, clone));
          }
          return response;
        })
        .catch(() => caches.match(request))
    );
    return;
  }

  // 静态资源：Cache First + 网络更新
  event.respondWith(
    caches.match(request).then((cached) => {
      const fetchPromise = fetch(request).then((response) => {
        if (response && response.ok && response.status === 200) {
          const clone = response.clone();
          caches.open(STATIC_CACHE).then((cache) => cache.put(request, clone));
        }
        return response;
      }).catch(() => cached);
      return cached || fetchPromise;
    })
  );
});

// 推送通知（P5+ 预留）
self.addEventListener("push", (event) => {
  if (!event.data) return;
  const data = event.data.json();
  event.waitUntil(
    self.registration.showNotification(data.title || "Edu 家长端", {
      body: data.body || "",
      icon: "/icon-192.png",
      badge: "/icon-192.png",
      data: { url: data.url || "/parent/dashboard" },
    })
  );
});

// 点击通知跳转
self.addEventListener("notificationclick", (event) => {
  event.notification.close();
  const targetUrl = event.notification.data?.url || "/parent/dashboard";
  event.waitUntil(
    self.clients.matchAll({ type: "window" }).then((clients) => {
      const existing = clients.find((c) => c.url.includes(targetUrl));
      if (existing) {
        return existing.focus();
      }
      return self.clients.openWindow(targetUrl);
    })
  );
});