import {
  createContext,
  useContext,
  useState,
  useCallback,
  useMemo,
  useEffect,
  type ReactNode,
} from "react";
import { login as loginApi, getMe, logout as logoutApi } from "../services/authApi";

// ============================================================
// 类型
// ============================================================

export interface UserInfo {
  id: string;
  username: string;
  display_name: string;
  role: string;
}

interface AuthState {
  user: UserInfo | null;
  token: string | null;
  loading: boolean;
}

interface AuthContextValue extends AuthState {
  login: (username: string, password: string) => Promise<void>;
  /** 登出。async 是因为必须先 await 审计上报、再清 token —— 顺序反了会丢日志 */
  logout: () => Promise<void>;
  isAuthenticated: boolean;
}

// ============================================================
// Token 存储 key
// ============================================================

const ACCESS_TOKEN_KEY = "track_admin_token";
const REFRESH_TOKEN_KEY = "track_admin_refresh_token";
const USER_KEY = "track_admin_user";

// ============================================================
// Context
// ============================================================

const AuthContext = createContext<AuthContextValue | null>(null);

export function useAuth() {
  const ctx = useContext(AuthContext);
  if (!ctx) throw new Error("useAuth 必须在 AuthProvider 内使用");
  return ctx;
}

// ============================================================
// Provider
// ============================================================

export function AuthProvider({ children }: { children: ReactNode }) {
  const [state, setState] = useState<AuthState>({
    user: null,
    token: null,
    loading: true,
  });

  // 初始化：从 localStorage 恢复双 Token
  useEffect(() => {
    const savedToken = localStorage.getItem(ACCESS_TOKEN_KEY);
    const savedUser = localStorage.getItem(USER_KEY);
    if (savedToken && savedUser) {
      try {
        const user = JSON.parse(savedUser) as UserInfo;
        setState({ user, token: savedToken, loading: false });
        // 后台静默验证 token 是否仍有效
        getMe(savedToken)
          .then((fresh) => {
            setState((prev) => ({ ...prev, user: fresh }));
            localStorage.setItem(USER_KEY, JSON.stringify(fresh));
          })
          .catch((err) => {
            // 验证失败不踢出用户 — 真正的过期由业务 API 401 拦截器
            // 通过 Refresh Token 无感刷新，彻底失败才跳转登录
            console.error(
              "[Auth] Token 后台验证失败（保留本地登录态，依赖拦截器刷新）:",
              err?.message ?? err,
            );
          });
      } catch {
        logoutInternal();
      }
    } else {
      setState((prev) => ({ ...prev, loading: false }));
    }
  }, []);

  function logoutInternal() {
    localStorage.removeItem(ACCESS_TOKEN_KEY);
    localStorage.removeItem(REFRESH_TOKEN_KEY);
    localStorage.removeItem(USER_KEY);
    setState({ user: null, token: null, loading: false });
  }

  const login = useCallback(async (username: string, password: string) => {
    const result = await loginApi(username, password);
    const accessToken = result.access_token;
    const refreshToken = result.refresh_token;
    const user: UserInfo = result.user;

    // 存储双 Token
    localStorage.setItem(ACCESS_TOKEN_KEY, accessToken);
    localStorage.setItem(REFRESH_TOKEN_KEY, refreshToken);
    localStorage.setItem(USER_KEY, JSON.stringify(user));
    setState({ user, token: accessToken, loading: false });
  }, []);

  const logout = useCallback(async () => {
    // ⚠️ 必须【先 await 上报、再清 token】。两边顺序反了或不等，退出就留不下痕：
    //   1) axios 的请求拦截器是在微任务里执行的，它去 localStorage 读 token 时，
    //      同步的 logoutInternal() 早已把 token 清掉 → 请求不带 Authorization
    //      → 后端只能记成「未认证」，退出归因不到人；
    //   2) 调用方点完退出还会立刻 navigate 到登录页，进一步压缩执行窗口。
    // 所以这里(async) + 调用方(await) 两处都得改，只改一处等于没改。
    // 失败绝不影响退出：JWT 无状态，服务端本就不需要它成功。
    try {
      await logoutApi();
    } catch {
      /* 静默：断网/超时也照退不误 */
    }
    logoutInternal();
  }, []);

  const ctxValue = useMemo<AuthContextValue>(
    () => ({
      ...state,
      login,
      logout,
      isAuthenticated: !!state.token && !!state.user,
    }),
    [state, login, logout],
  );

  return (
    <AuthContext.Provider value={ctxValue}>
      {children}
    </AuthContext.Provider>
  );
}