// /composables/useAuth.ts

interface User {
  id: string;
  email: string;
  nickname: string;
  avatar: string | null;
  coins: number;
  exp: number;
  dailyStreak: number;
  soundOn: boolean;
  confettiOn: boolean;
  createdAt: string;
  updatedAt: string;
}

export function useAuth() {
  // All Nuxt composables that require instance access MUST be called inside the setup function.
  // useState is how we create shared, SSR-safe state in Nuxt.
  const user = useState<User | null>('user', () => null);
  const initialized = useState('auth_initialized', () => false);
  const loading = ref(false); // This is a local, non-shared loading ref for fetchMe's internal use

  const api = useApi();
  const isAuthenticated = computed(() => !!user.value);

  const fetchMe = async () => {
    // This function can be called multiple times, but the logic inside
    // will only run once thanks to the initialized flag.
    if (initialized.value) return;
    
    loading.value = true;
    try {
      // The backend returns the user object nested under a 'user' key.
      const response = await api<{ user: User }>('/auth/me', { method: 'GET' });
      user.value = response.user; // Correctly assign the nested user object
    } catch (error) {
      user.value = null; // Silently set user to null on 401
    } finally {
      loading.value = false;
      initialized.value = true; // Mark as initialized after the first attempt
    }
  };

  const login = async (email, password) => {
    // The calling component is responsible for its own loading state.
    // This function just performs the action.
    await api('/auth/login', {
      method: 'POST',
      body: { email, password },
    });
    // After a successful login, allow a re-fetch of the user state.
    initialized.value = false;
    await fetchMe();
  };

  const logout = async () => {
    try {
      await api('/auth/logout', { method: 'POST' });
    } finally {
      // Always clear state and redirect, regardless of API call success.
      user.value = null;
      initialized.value = false;
      await navigateTo('/login');
    }
  };

  const updateUser = (partialUser: Partial<User>) => {
    if (user.value) {
      user.value = { ...user.value, ...partialUser };
    }
  };

  // Expose the state and methods.
  return {
    user,
    isAuthenticated,
    initialized,
    fetchMe,
    login,
    logout,
    updateUser,
  };
}