update frontend gql

-export const defaults = {};
+export const defaults = {
+  isLoggedIn: Boolean(localStorage.getItem("token") || false),
+};
 
-export const resolvers = {};
+export const resolvers = {
+  Mutation: {
+    logUserIn: (_, { token }, { cache }) => {
+      localStorage.setItem("token", token);
+      cache.writeData({
+        data: {
+          isLoggedIn: true,
+        },
+      });
+      return null;
+    },
+    logUserOut: (_, __, { cache }) => {
+      localStorage.removeItem("token");
+      window.location.reload();
+      return null;
+    },
+  },
+};