Implement redux.

hooks/useUser.js

@@ -0,0 +1,42 @@
+import { useState, useEffect } from 'react';
+import { useDispatch, useSelector } from 'react-redux';
+import { updateUser } from 'redux/actions/user';
+
+export async function fetchUser() {
+  const res = await fetch('/api/auth/verify');
+
+  if (!res.ok) {
+    return null;
+  }
+
+  return await res.json();
+}
+
+export default function useUser() {
+  const dispatch = useDispatch();
+  const storeUser = useSelector(state => state.user);
+  const [loading, setLoading] = useState(!storeUser);
+  const [user, setUser] = useState(storeUser || null);
+
+  useEffect(() => {
+    if (!loading && user) {
+      return;
+    }
+
+    setLoading(true);
+
+    fetchUser().then(async user => {
+      if (!user) {
+        window.location.href = '/login';
+        return;
+      }
+
+      await dispatch(updateUser({ user: user }));
+
+      setUser(user);
+      setLoading(false);
+    });
+  }, []);
+
+  return { user, loading };
+}