finance-website/frontend/src/pages/Auth.jsx

import React, { useState } from 'react';
import { useNavigate } from 'react-router-dom';

export default function Auth() {
  const [isLogin, setIsLogin] = useState(true);
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [firstName, setFirstName] = useState('');
  const [error, setError] = useState('');
  const navigate = useNavigate();

  const handleSubmit = async (e) => {
    e.preventDefault();
    setError('');
    
    const url = isLogin ? '/api/auth/login' : '/api/auth/register';
    const payload = isLogin ? { email, password } : { email, password, first_name: firstName };

    try {
      const res = await fetch(url, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(payload)
      });
      
      const data = await res.json();
      if (!res.ok) {
        throw new Error(data.error || 'Ошибка авторизации');
      }

      localStorage.setItem('token', data.token);
      localStorage.setItem('user', JSON.stringify(data.user));
      navigate('/');
    } catch (err) {
      setError(err.message);
    }
  };

  return (
    <div className="auth-container">
      <div className="auth-box">
        <h2>{isLogin ? 'Вход в систему' : 'Регистрация'}</h2>
        {error && <div style={{ color: 'var(--danger)', marginBottom: '1rem', textAlign: 'center' }}>{error}</div>}
        <form onSubmit={handleSubmit}>
          {!isLogin && (
            <div className="form-group">
              <label>Имя</label>
              <input type="text" value={firstName} onChange={e => setFirstName(e.target.value)} required />
            </div>
          )}
          <div className="form-group">
            <label>Email</label>
            <input type="email" value={email} onChange={e => setEmail(e.target.value)} required />
          </div>
          <div className="form-group">
            <label>Пароль</label>
            <input type="password" value={password} onChange={e => setPassword(e.target.value)} required />
          </div>
          <button type="submit">{isLogin ? 'Войти' : 'Зарегистрироваться'}</button>
        </form>
        <div className="toggle-link">
          <a href="#" onClick={(e) => { e.preventDefault(); setIsLogin(!isLogin); }}>
            {isLogin ? 'Нет аккаунта? Зарегистрироваться' : 'Уже есть аккаунт? Войти'}
          </a>
        </div>
      </div>
    </div>
  );
}