(() => {
  const form = document.getElementById("client-auth");
  const message = document.getElementById("client-auth-status");
  const button = form.querySelector("button");
  let accessToken;
  let refreshToken;
  let accessExpiry = 0;

  async function requestToken(operation, data) {
    const response = await fetch("/api/v1/auth/" + operation, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(data),
    });
    const result = await response.json();
    if (!response.ok || result.code !== 0) throw new Error(result.message || "鉴权失败");
    accessToken = result.data.access_token;
    accessExpiry = Date.now() + result.data.expires_in * 1000;
    return result.data;
  }

  form.addEventListener("submit", async (event) => {
    event.preventDefault();
    button.disabled = true;
    const data = new FormData(form);
    try {
      const result = await requestToken("login", {
        username: data.get("username"),
        password: data.get("password"),
      });
      refreshToken = result.refresh_token;
      message.textContent = "已登录。访问令牌过期时会自动刷新。";
    } catch (error) {
      message.textContent = error.message;
    } finally {
      form.elements.namedItem("password").value = "";
      button.disabled = false;
    }
  });

  async function refresh() {
    if (!refreshToken) throw new Error("请先登录，再提交图片。");
    try {
      await requestToken("refresh", { refresh_token: refreshToken });
    } catch (error) {
      accessToken = refreshToken = undefined;
      message.textContent = "请重新登录。";
      throw error;
    }
  }

  window.hairClientFetch = async (path, options) => {
    if (Date.now() >= accessExpiry || !accessToken) await refresh();
    const send = () => {
      const headers = new Headers(options.headers);
      headers.set("Authorization", "Bearer " + accessToken);
      return fetch(path, { ...options, headers });
    };
    const response = await send();
    if (response.status !== 401) return response;
    await refresh();
    return send();
  };
})();