From 59178ff276d6151b9db206c5997a4c0501ea75fa Mon Sep 17 00:00:00 2001
From: Luke Childs <lukechilds123@gmail.com>
Date: Wed, 22 Mar 2017 20:49:31 +0800
Subject: [PATCH] Return cached response immediately if not stale

---
 index.js     | 22 +++++++++++++++++++++-
 package.json |  1 +
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 17a89bf52..735244d5c 100644
--- a/index.js
+++ b/index.js
@@ -18,6 +18,7 @@ const isRetryAllowed = require('is-retry-allowed');
 const Buffer = require('safe-buffer').Buffer;
 const expired = require('expired');
 const normalizeUrl = require('normalize-url');
+const Response = require('http-response-object');
 const pkg = require('./package');
 
 function requestAsEventEmitter(opts) {
@@ -99,7 +100,22 @@ function requestAsEventEmitter(opts) {
 		});
 	};
 
-	get(opts);
+	if (opts.cache && opts.method === 'GET') {
+		const key = normalizeUrl(requestUrl);
+		opts.cache.get(key, (err, value) => {
+			if (err) {
+				return get(opts);
+			}
+			const cachedResponse = JSON.parse(value);
+			if (expired(cachedResponse.headers) === false) {
+				const response = responseFromCache(requestUrl, cachedResponse);
+				ee.emit('response', response);
+			}
+		});
+	} else {
+		get(opts);
+	}
+
 	return ee;
 }
 
@@ -315,6 +331,10 @@ function normalizeArguments(url, opts) {
 	return opts;
 }
 
+function responseFromCache(url, cachedResponse) {
+	return new Response(200, cachedResponse.headers, Buffer.from(cachedResponse.body), url);
+}
+
 function got(url, opts) {
 	try {
 		return asPromise(normalizeArguments(url, opts));
diff --git a/package.json b/package.json
index 92207baa0..f91fc6398 100644
--- a/package.json
+++ b/package.json
@@ -46,6 +46,7 @@
     "duplexer3": "^0.1.4",
     "expired": "^1.3.8",
     "get-stream": "^3.0.0",
+    "http-response-object": "^1.1.0",
     "is-redirect": "^1.0.0",
     "is-retry-allowed": "^1.0.0",
     "is-stream": "^1.0.0",