import { useCallback, useEffect, useState } from "react";
import type { AuthState, UserSession } from "./types.js";

/**
 * useAuth - 会话状态管理
 *
 * 用途：管理用户登录状态、token、用户信息。
 * P2 阶段：token 存储在 localStorage（F12 裁决），P6 评估迁移 httpOnly Cookie。
 *
 * 注意：本 hook 提供"状态管理"骨架，具体的登录/登出 API 调用
 * 由 apps/* 注入（通过 AuthProvider Context 或 props 传入 fetcher）。
 *
 * @example
 * const { user, isAuthenticated, login, logout } = useAuth();
 */

const TOKEN_KEY = "edu_auth_token";
const USER_KEY = "edu_auth_user";

export interface UseAuthReturn extends AuthState {
  /** 登录（由调用方注入 fetcher） */
  login: (token: string, user: UserSession) => void;
  /** 登出 */
  logout: () => void;
  /** 刷新用户信息 */
  refreshUser: (user: UserSession) => void;
}

export function useAuth(): UseAuthReturn {
  const [state, setState] = useState<AuthState>({
    user: null,
    token: null,
    isAuthenticated: false,
    isLoading: true,
  });

  // 初始化：从 localStorage 读取 token + user（F12 裁决 P2 用 localStorage）
  useEffect(() => {
    try {
      const token = localStorage.getItem(TOKEN_KEY);
      const userJson = localStorage.getItem(USER_KEY);
      const user = userJson ? (JSON.parse(userJson) as UserSession) : null;

      setState({
        user,
        token,
        isAuthenticated: Boolean(token && user),
        isLoading: false,
      });
    } catch {
      setState({
        user: null,
        token: null,
        isAuthenticated: false,
        isLoading: false,
      });
    }
  }, []);

  const login = useCallback((token: string, user: UserSession): void => {
    localStorage.setItem(TOKEN_KEY, token);
    localStorage.setItem(USER_KEY, JSON.stringify(user));
    setState({
      user,
      token,
      isAuthenticated: true,
      isLoading: false,
    });
  }, []);

  const logout = useCallback((): void => {
    localStorage.removeItem(TOKEN_KEY);
    localStorage.removeItem(USER_KEY);
    setState({
      user: null,
      token: null,
      isAuthenticated: false,
      isLoading: false,
    });
  }, []);

  const refreshUser = useCallback((user: UserSession): void => {
    localStorage.setItem(USER_KEY, JSON.stringify(user));
    setState((prev) => ({ ...prev, user }));
  }, []);

  return {
    ...state,
    login,
    logout,
    refreshUser,
  };
}