frontend: Add AuthContext.

This commit adds an AuthContext exposing the functions to
get and set current auth status. The context is then used in the
App component.

frontend/src/App.tsx

@@ -5,6 +5,7 @@ import AppLayout from './pages/AppLayout';
 import Error from './pages/Error';
 import Game from './pages/Game';
 import About from './pages/About';
+import { AuthProvider } from './contexts/AuthContext';
 
 const router = createBrowserRouter([
     {
@@ -27,7 +28,13 @@ const router = createBrowserRouter([
 ]);
 
 function App() {
-    return <RouterProvider router={router} />;
+    return (
+        <AuthProvider>
+            <>
+                <RouterProvider router={router} />;
+            </>
+        </AuthProvider>
+    );
 }
 
 export default App;

frontend/src/contexts/AuthContext.tsx

@@ -0,0 +1,57 @@
+import {
+    ReactElement,
+    createContext,
+    useCallback,
+    useContext,
+    useState,
+} from 'react';
+
+export type User = {
+    name: string;
+    email: string;
+};
+
+export type AuthContextProps = {
+    getUser: () => User | null;
+    login: () => void;
+    logout: () => void;
+    isLoggedIn: () => boolean;
+};
+export const AuthContext = createContext<AuthContextProps>({
+    getUser: () => null,
+    login: () => {},
+    logout: () => {},
+    isLoggedIn: () => false,
+});
+
+// eslint-disable-next-line react-refresh/only-export-components
+export function useAuth() {
+    return useContext(AuthContext);
+}
+
+export function AuthProvider({ children }: { children: ReactElement }) {
+    const [user, setUser] = useState<User | null>(null);
+
+    const login = useCallback(() => {
+        setUser({
+            name: 'John Doe',
+            email: '',
+        });
+    }, []);
+
+    const logout = useCallback(() => {}, []);
+
+    const getUser = useCallback(() => {
+        return user;
+    }, [user]);
+
+    const isLoggedIn = useCallback(() => {
+        return !!user;
+    }, [user]);
+
+    return (
+        <AuthContext.Provider value={{ getUser, login, logout, isLoggedIn }}>
+            {children}
+        </AuthContext.Provider>
+    );
+}