From cd54e9317ff0396a34bafacce2ff2c056a4b0cee Mon Sep 17 00:00:00 2001
From: Gus Caplan <me@gus.host>
Date: Fri, 27 Oct 2017 08:36:53 -0500
Subject: [PATCH] Time Difference in REST (#2057)

---
 src/rest/RESTManager.js             | 10 ++++++++++
 src/rest/handlers/RequestHandler.js |  7 +++----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/rest/RESTManager.js b/src/rest/RESTManager.js
index 48476cca6..d62423979 100644
--- a/src/rest/RESTManager.js
+++ b/src/rest/RESTManager.js
@@ -12,12 +12,22 @@ class RESTManager {
     this.globallyRateLimited = false;
     this.tokenPrefix = tokenPrefix;
     this.versioned = true;
+    this.timeDifferences = [];
   }
 
   get api() {
     return routeBuilder(this);
   }
 
+  get timeDifference() {
+    return Math.round(this.timeDifferences.reduce((a, b) => a + b, 0) / this.timeDifferences.length);
+  }
+
+  set timeDifference(ms) {
+    this.timeDifferences.unshift(ms);
+    if (this.timeDifferences.length > 5) this.timeDifferences.length = 5;
+  }
+
   getAuth() {
     const token = this.client.token || this.client.accessToken;
     const prefixed = !!this.client.application || (this.client.user && this.client.user.bot);
diff --git a/src/rest/handlers/RequestHandler.js b/src/rest/handlers/RequestHandler.js
index aaeed9d69..64e9ea72b 100644
--- a/src/rest/handlers/RequestHandler.js
+++ b/src/rest/handlers/RequestHandler.js
@@ -9,7 +9,6 @@ class RequestHandler {
     this.limit = Infinity;
     this.resetTime = null;
     this.remaining = 1;
-    this.timeDifference = 0;
 
     this.queue = [];
   }
@@ -32,7 +31,7 @@ class RequestHandler {
       const finish = timeout => {
         if (timeout || this.limited) {
           if (!timeout) {
-            timeout = this.resetTime - Date.now() + this.timeDifference + this.client.options.restTimeOffset;
+            timeout = this.resetTime - Date.now() + this.manager.timeDifference + this.client.options.restTimeOffset;
           }
           // eslint-disable-next-line prefer-promise-reject-errors
           reject({ timeout });
@@ -50,7 +49,7 @@ class RequestHandler {
             this.client.emit(RATE_LIMIT, {
               timeout,
               limit: this.limit,
-              timeDifference: this.timeDifference,
+              timeDifference: this.manager.timeDifference,
               method: item.request.method,
               path: item.request.path,
               route: item.request.route,
@@ -66,7 +65,7 @@ class RequestHandler {
           this.limit = Number(res.headers['x-ratelimit-limit']);
           this.resetTime = Number(res.headers['x-ratelimit-reset']) * 1000;
           this.remaining = Number(res.headers['x-ratelimit-remaining']);
-          this.timeDifference = Date.now() - new Date(res.headers.date).getTime();
+          this.manager.timeDifference = Date.now() - new Date(res.headers.date).getTime();
         }
         if (err) {
           if (err.status === 429) {