Hello I am making login app used firebase google login. I want to save the user in the user-reducer. The console shows user info from the firebase! but, It keeps shows undefined. I don't know why it shows like these. Please advised!

[user-action ]
import { UserType } from './user.types';
export const login = ({ currentUser }) => ({
  type: UserType.USER_LOGIN,
  payload: currentUser,
});

[user-types ]

export const UserType = {
  USER_LOGIN: 'USER_LOGIN',
};

[user-reducer]

import { UserType } from './user.types';
const INITAIL_STATE = {
  user: [],
};
const userReducer = (state = INITAIL_STATE, action) => {
  switch (action.type) {
    case UserType.USER_LOGIN:
      return {
        ...state,
        user: action.payload,
      };
    default:
      return state;
  }
};

export default userReducer;

[Login.js]

const Login = ({ googleLogin }) => {
const [currentUser, setCurrentUser] = useState(null);

  const getUser = new Promise((resolve, reject) => {
    console.log('doing...');
    firebase.auth().onAuthStateChanged(setCurrentUser);
    resolve(currentUser);
    console.log(currentUser);
  });

  getUser
    .then(user => {
      googleLogin(user);
    })
    .catch(error => {
      console.log(error);
    });

 .... 

const mapDispatchToProps = dispatch => ({
  onModal: () => dispatch(modalHandler()),
  googleLogin: currentUser => dispatch(login(currentUser)),
});

export default connect(null, mapDispatchToProps)(Login);