(function initializeCognitiveAgentNetwork() {
  const nativeFetch = window.fetch.bind(window);
  const listeners = new Set();
  const state = {
    status: navigator.onLine === false ? "offline" : "connecting",
    lastSuccessAt: null,
    lastError: null,
  };
  let probeTimer = null;

  function snapshot() {
    return { ...state };
  }

  function renderBadge() {
    const badge = document.querySelector("#connectionBadge");
    if (!badge) return;
    const presentation = {
      connecting: ["neutral", "loader-circle", "连接中"],
      online: ["", "wifi", "服务已连接"],
      degraded: ["warning", "wifi-low", "连接不稳定"],
      offline: ["danger", "wifi-off", "服务已断开"],
    }[state.status];
    badge.className = `status-badge connection-badge ${presentation[0]}`.trim();
    badge.innerHTML = `<i data-lucide="${presentation[1]}"></i><span>${presentation[2]}</span>`;
    badge.title = state.lastError || presentation[2];
    window.lucide?.createIcons?.({
      attrs: { "aria-hidden": "true" },
      nodes: [badge],
    });
  }

  function publish(status, error = null) {
    const changed = state.status !== status || state.lastError !== error;
    state.status = status;
    state.lastError = error;
    if (status === "online") state.lastSuccessAt = new Date().toISOString();
    renderBadge();
    if (!changed) return;
    const detail = snapshot();
    listeners.forEach((listener) => listener(detail));
    window.dispatchEvent(new CustomEvent("cognitive-agent:connection", { detail }));
  }

  function sleep(milliseconds) {
    return new Promise((resolve) => window.setTimeout(resolve, milliseconds));
  }

  async function request(input, options = {}) {
    const {
      timeoutMs = 10000,
      retries: configuredRetries,
      signal: callerSignal,
      ...fetchOptions
    } = options;
    const method = String(fetchOptions.method || "GET").toUpperCase();
    const retries = configuredRetries ?? (method === "GET" ? 1 : 0);
    let lastError;

    for (let attempt = 0; attempt <= retries; attempt += 1) {
      const controller = new AbortController();
      const abortFromCaller = () => controller.abort(callerSignal?.reason);
      callerSignal?.addEventListener("abort", abortFromCaller, { once: true });
      const timeout = window.setTimeout(() => controller.abort("timeout"), timeoutMs);
      try {
        const response = await nativeFetch(input, {
          ...fetchOptions,
          signal: controller.signal,
        });
        publish(response.status >= 500 ? "degraded" : "online",
          response.status >= 500 ? `服务返回 HTTP ${response.status}` : null);
        return response;
      } catch (error) {
        lastError = error;
        const message = controller.signal.aborted && !callerSignal?.aborted
          ? `请求超时（${Math.round(timeoutMs / 1000)} 秒）`
          : (error?.message || "网络请求失败");
        publish(attempt < retries ? "degraded" : "offline", message);
        if (callerSignal?.aborted || attempt >= retries || method !== "GET") {
          throw new Error(message, { cause: error });
        }
        await sleep(300 * (attempt + 1));
      } finally {
        window.clearTimeout(timeout);
        callerSignal?.removeEventListener("abort", abortFromCaller);
      }
    }
    throw lastError;
  }

  async function probe() {
    if (document.hidden) return;
    if (navigator.onLine === false) {
      publish("offline", "设备当前处于离线状态");
      return;
    }
    try {
      const response = await request("/api/health", {
        cache: "no-store",
        timeoutMs: 4000,
        retries: 0,
      });
      if (!response.ok && response.status !== 401) {
        publish("degraded", `健康检查返回 HTTP ${response.status}`);
      }
    } catch (_error) {
      // request() already published the detailed state.
    }
  }

  function startMonitoring() {
    if (probeTimer !== null) return;
    renderBadge();
    probe();
    probeTimer = window.setInterval(probe, 10000);
    window.addEventListener("online", () => {
      publish("connecting");
      probe();
    });
    window.addEventListener("offline", () => publish("offline", "设备当前处于离线状态"));
    document.addEventListener("visibilitychange", () => {
      if (!document.hidden) probe();
    });
  }

  window.CognitiveAgentNetwork = {
    request,
    probe,
    subscribe(listener) {
      listeners.add(listener);
      listener(snapshot());
      return () => listeners.delete(listener);
    },
    getState: snapshot,
    nativeFetch,
  };
  document.addEventListener("DOMContentLoaded", startMonitoring, { once: true });
})();