// /composables/useAuth.ts

interface User {
  id: number;
  email: string | null; // Can be null for anonymous users
  nickname: string | null;
  avatar: string | null;
  coins: number;
  exp: number;
  dailyStreak: number;
  soundOn: boolean;
  confettiOn: boolean;
  createdAt: string;
  updatedAt: string;
  isAnonymous?: boolean; // Flag to distinguish anonymous users
  anonymousSessionId?: string;
}

export function useAuth() {
  const user = useState<User | null>('user', () => null);
  const initialized = useState('auth_initialized', () => false);
  
  const api = useApi();

  // A user is fully authenticated only if they exist and are NOT anonymous.
  const isAuthenticated = computed(() => !!user.value && !user.value.isAnonymous);
  // A user is anonymous if they exist and have the isAnonymous flag.
  const isAnonymous = computed(() => !!user.value && !!user.value.isAnonymous);

  /**
   * Initializes the authentication state for EXISTING users.
   * It should be called once in app.vue.
   * It will only try to fetch a logged-in user via /api/auth/me.
   * If it fails, the user state remains null.
   */
  const initAuth = async () => {
    if (initialized.value) return;

    try {
      const response = await api<{ user: User }>('/auth/me');
      if (response.user) {
        user.value = { ...response.user, isAnonymous: false };
      } else {
        user.value = null;
      }
    } catch (error) {
      // It's expected this will fail for non-logged-in users.
      user.value = null;
    } finally {
      initialized.value = true;
    }
  };

  /**
   * Starts the onboarding process by creating a new anonymous user.
   */
  const startOnboarding = async () => {
    try {
      const anonymousUserData = await api<User>('/onboarding/initiate', { method: 'POST' });
      // Explicitly set isAnonymous to true for robustness
      user.value = { ...anonymousUserData, isAnonymous: true };
    } catch (anonError) {
      console.error('Could not initiate anonymous session:', anonError);
      // Optionally, show an error message to the user
      user.value = null;
    }
  };

  const register = async (email, password, nickname) => {
    await api('/auth/register', {
      method: 'POST',
      body: { email, password, nickname },
    });
    // After a successful registration, force a re-fetch of the new user state.
    initialized.value = false;
    await initAuth();
  };

  const login = async (email, password) => {
    await api('/auth/login', {
      method: 'POST',
      body: { email, password },
    });
    // After a successful login, force a re-fetch of the new user state.
    initialized.value = false;
    await initAuth();
  };

  const logout = async () => {
    try {
      await api('/auth/logout', { method: 'POST' });
    } finally {
      user.value = null;
      await navigateTo('/');
    }
  };

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

  return {
    user,
    isAuthenticated,
    isAnonymous, // Expose this new state
    initialized,
    initAuth, // Called from app.vue
    startOnboarding, // Called from index.vue
    register, // Expose register function
    login,
    logout,
    updateUser,
  };
}