add useQuery, @client query.

@@ -2,11 +2,31 @@ import React from "react";
 import Header from "../Components/Header";
 import Main from "../Components/Main";
 import Footer from "../Components/Footer";
+import { gql } from "@apollo/client";
+import { useQuery } from "@apollo/react-hooks";
+
+const checkLogin = gql`
+  {
+    isLoggedIn @client
+  }
+`;
 
 export default () => {
+  const {
+    data: { isLoggedIn },
+  } = useQuery(checkLogin);
+
+  let btnState;
+
+  if (isLoggedIn) {
+    btnState = "roomlist";
+  } else {
+    btnState = "main";
+  }
+
   return (
     <>
-      <Header />
+      <Header btnStateProp={btnState} />
       <Main />
       <Footer />
     </>