Login.jsx

import React, { useState, useContext } from 'react';
import { useHistory, useLocation } from 'react-router-dom';
import StoreContext from 'components/Store/Context';
import UIButton from 'components/UI/Button/Button';

import './Login.css';

function initialState() {
  return { user: '', password: '' };
}

function login({ user, password }) {
  if (user === 'admin' && password === 'admin') {
    return { token: '1234' };
  }
  return { error: 'Usuário ou senha inválido' };
}

const UserLogin = () => {
  const [values, setValues] = useState(initialState);
  const [error, setError] = useState(null);
  const { setToken } = useContext(StoreContext);
  const history = useHistory();
  const location = useLocation();

  function onChange(event) {
    const { value, name } = event.target;

    setValues({
      ...values,
      [name]: value
    });
  }

  function onSubmit(event) {
    event.preventDefault();

    const { token, error } = login(values);

    if (token) {
      setToken(token);
      if (location?.state.redirectOnAuthenticated) {
        return history.push(location.state.from);  
      }
      return history.push('/');
    }

    setError(error);
    setValues(initialState);
  }

  return (
    <div className="user-login">
      <h1 className="user-login__title">Acessar o Sistema</h1>
      <form onSubmit={onSubmit}>
        <div className="user-login__form-control">
          <label htmlFor="user">Usuário</label>
          <input
            id="user"
            type="text"
            name="user"
            onChange={onChange}
            value={values.user}
          />
        </div>
        <div className="user-login__form-control">
          <label htmlFor="password">Senha</label>
          <input
            id="password"
            type="password"
            name="password"
            onChange={onChange}
            value={values.password}
          />
        </div>
        {error && (
          <div className="user-login__error">{error}</div>
        )}
        <UIButton
          type="submit"
          theme="contained-green"
          className="user-login__submit-button"
          rounded
        >
          Entrar
        </UIButton>
      </form>
    </div>
  );
};

export default UserLogin;