fix login

frontend/src/components/auth/LoginCallback.tsx

@@ -1,4 +1,4 @@
-import React, { useEffect, useState } from 'react';
+import React, { useEffect, useRef, useState } from 'react';
 import { useNavigate, useSearchParams } from 'react-router-dom';
 import { useAuth } from '../../contexts/AuthContext';
 import { Box, CircularProgress, Typography, Alert, Button } from '@mui/material';
@@ -8,8 +8,12 @@ const LoginCallback: React.FC = () => {
   const [searchParams] = useSearchParams();
   const { login } = useAuth();
   const [error, setError] = useState<string>('');
+  const hasCalledLogin = useRef(false);
 
   useEffect(() => {
+    if (hasCalledLogin.current) return;
+    hasCalledLogin.current = true;
+
     const handleCallback = async () => {
       const code = searchParams.get('code');
       const errorParam = searchParams.get('error');

frontend/src/contexts/AuthContext.tsx

@@ -1,4 +1,4 @@
-import React, { createContext, useContext, useState, useEffect, ReactNode } from 'react';
+import React, { createContext, useCallback, useContext, useState, useEffect, ReactNode } from 'react';
 import { AuthContextType, AuthState, User } from '../types/auth.types';
 import { authService } from '../services/auth';
 import { getToken, setToken, removeToken, getUser, setUser, removeUser } from '../utils/storage';
@@ -61,7 +61,7 @@ export const AuthProvider: React.FC<AuthProviderProps> = ({ children }) => {
     initializeAuth();
   }, []);
 
-  const login = async (code: string): Promise<void> => {
+  const login = useCallback(async (code: string): Promise<void> => {
     try {
       setState((prev) => ({ ...prev, isLoading: true }));
 
@@ -94,9 +94,9 @@ export const AuthProvider: React.FC<AuthProviderProps> = ({ children }) => {
       notification.showError('Anmeldung fehlgeschlagen. Bitte versuchen Sie es erneut.');
       throw error;
     }
-  };
+  }, [notification]);
 
-  const logout = (): void => {
+  const logout = useCallback((): void => {
     // Call backend logout (fire and forget)
     authService.logout().catch((error) => {
       console.error('Backend logout failed:', error);
@@ -119,9 +119,9 @@ export const AuthProvider: React.FC<AuthProviderProps> = ({ children }) => {
     setTimeout(() => {
       window.location.href = '/login';
     }, 1000);
-  };
+  }, [notification]);
 
-  const refreshAuth = async (): Promise<void> => {
+  const refreshAuth = useCallback(async (): Promise<void> => {
     try {
       const user = await authService.getCurrentUser();
       setUser(user);
@@ -130,7 +130,7 @@ export const AuthProvider: React.FC<AuthProviderProps> = ({ children }) => {
       console.error('Failed to refresh user data:', error);
       logout();
     }
-  };
+  }, [logout]);
 
   const value: AuthContextType = {
     ...state,