सुरक्षित रूट और प्रमाणीकरण गार्ड

const AuthContext = React.createContext(null);

function AuthProvider({ children }) {
  const [user, setUser] = useState(null);
  const login = async (creds) => { const u = await apiLogin(creds); setUser(u); };
  const logout = () => setUser(null);
  return (
    <AuthContext.Provider value={{ user, login, logout }}>
      {children}
    </AuthContext.Provider>
  );
}

export const useAuth = () => useContext(AuthContext);

import { Navigate, Outlet } from 'react-router-dom';

function PrivateRoute() {
  const { user } = useAuth();
  if (!user) return <Navigate to="/login" replace />;
  return <Outlet />;
}

// Usage in router:
{ element: <PrivateRoute />, children: [
  { path: '/dashboard', element: <Dashboard /> },
]}

function PrivateRoute() {
  const { user } = useAuth();
  const location = useLocation();
  if (!user) {
    return <Navigate to="/login" state={{ from: location }} replace />;
  }
  return <Outlet />;
}

// In login handler:
const location = useLocation();
const from = location.state?.from?.pathname || '/';
navigate(from, { replace: true });

import { redirect } from 'react-router-dom';

function requireAuth() {
  const token = localStorage.getItem('token');
  if (!token) throw redirect('/login');
  return token;
}

const router = createBrowserRouter([
  {
    path: '/dashboard',
    loader: requireAuth,
    element: <Dashboard />,
  },
]);

function AdminRoute() {
  const { user } = useAuth();
  if (!user) return <Navigate to="/login" replace />;
  if (user.role !== 'admin') return <Navigate to="/unauthorized" replace />;
  return <Outlet />;
}

function PrivateRoute() {
  const { user, isLoading } = useAuth();
  if (isLoading) return <Spinner />;
  if (!user) return <Navigate to="/login" replace />;
  return <Outlet />;
}

const router = createBrowserRouter([
  { path: '/login', element: <Login /> },
  {
    element: <PrivateRoute />,
    children: [
      { path: '/dashboard', element: <Dashboard /> },
      { path: '/profile', element: <Profile /> },
      { path: '/settings', element: <Settings /> },
    ],
  },
]);

function isTokenValid(token) {
  const payload = JSON.parse(atob(token.split('.')[1]));
  return payload.exp * 1000 > Date.now();
}

function requireAuth() {
  const token = localStorage.getItem('token');
  if (!token || !isTokenValid(token)) throw redirect('/login');
  return token;
}

async function requireAuth() {
  let token = localStorage.getItem('token');
  if (!token || isExpired(token)) {
    token = await refreshToken();
    if (!token) throw redirect('/login');
    localStorage.setItem('token', token);
  }
  return token;
}