From 2d60fefc0e973f064e6416dfdf33a523b9b1d940 Mon Sep 17 00:00:00 2001
From: Justin Campbell <campb303@w2vm4.ecn.purdue.edu>
Date: Wed, 25 Nov 2020 18:06:57 -0500
Subject: [PATCH] Add auto refresh for access tokens

---
 src/components/AuthProvider/AuthProvider.js | 54 +++++++++++++++------
 1 file changed, 39 insertions(+), 15 deletions(-)

diff --git a/src/components/AuthProvider/AuthProvider.js b/src/components/AuthProvider/AuthProvider.js
index cd11258..6643208 100644
--- a/src/components/AuthProvider/AuthProvider.js
+++ b/src/components/AuthProvider/AuthProvider.js
@@ -1,6 +1,7 @@
 import React, { useState, createContext, useContext, useEffect } from "react";
 import { useCookies } from "react-cookie";
 import { refresh } from "../../auth/";
+import decodeJWT from "jwt-decode";
 
 
 
@@ -22,23 +23,46 @@ export default function AuthProvider({ children }) {
 
 	const [cookies] = useCookies();
 
+	async function tryRefresh(csrf_refresh_token){
+		if (csrf_refresh_token === undefined){
+			return false;
+		}
+	
+		const new_access_token = await refresh(csrf_refresh_token);
+		if (!new_access_token){
+			console.error("Failed to refresh access token.")
+			return false;
+		}
+	
+		setToken(new_access_token);
+		setLoggedIn(true);
+	}
+
+	// Attempt to refresh token on page load
 	useEffect( _ => {
-		async function tryRefresh(csrf_refresh_token){
-			if (csrf_refresh_token === undefined){
-				return false;
-			}
-
-			let new_access_token = await refresh(csrf_refresh_token);
-			if (!new_access_token){
-				console.error("Failed to refresh access token.")
-				return false;
-			}
-
-			setToken(new_access_token);
-			setLoggedIn(true);
+		(async () => {
+			await tryRefresh(cookies.csrf_refresh_token);
+		})();
+	}, [cookies]);
+
+	// Auto update token
+	useEffect( () => {
+		if (token === null) {
+			return undefined;
 		}
-		tryRefresh(cookies.csrf_refresh_token);
-	}, []);
+
+		// 5 second buffer for access token refresh
+		const refersh_buffer_time = 5000;
+		const access_token_expiration_claim = decodeJWT(token).exp
+		const access_token_expiration_time = new Date(0).setUTCSeconds(access_token_expiration_claim);
+		const miliseconds_to_access_token_expiration = (access_token_expiration_time - Date.now())
+
+		const timer = setTimeout( async () => {
+			await tryRefresh(cookies.csrf_refresh_token);
+		}, miliseconds_to_access_token_expiration - refersh_buffer_time);
+
+		return () => clearTimeout(timer);
+	}, [token, cookies]);
 
 	return (
 		<LoginContext.Provider value={loggedIn}>