Added Redis cache support

README.md

@@ -41,3 +41,16 @@ Result:
     "400x400": "https://pbs.twimg.com/profile_images/776738772759277569/hfaM5zhA_400x400.jpg"
 }
 ```
+
+## Requirements
+
+[Redis](https://redis.io/) is required if caching is wanted. You will also need Twitter credentials that can be created here: [https://apps.twitter.com/](https://apps.twitter.com/)
+
+Environment Variables:
+```
+TWITTER_CONSUMER_KEY=
+TWITTER_CONSUMER_SECRET=
+TWITTER_ACCESS_TOKEN_KEY=
+TWITTER_ACCESS_TOKEN_SECRET=
+REDIS_URL=
+```

cache.js

@@ -0,0 +1,33 @@
+let redis, redisAvailable;
+
+if (process.env.REDIS_URL) {
+  redis = require("redis").createClient({ url: process.env.REDIS_URL });
+
+  redis.on('error', err => {
+    console.log(err);
+    redisAvailable = false;
+  });
+
+  redis.on('ready', () => {
+    console.log('Redis ready');
+    redisAvailable = true;
+  });
+}
+
+const get = async key => {
+  if (!redisAvailable) return;
+  return new Promise(resolve => {
+    redis.get(key, (err, data) => {
+      return resolve(data ? JSON.parse(data) : data);
+    });
+  });
+};
+
+const save = (key, data) => {
+  if (!redisAvailable) return;
+  redis.set(key, JSON.stringify(data), 'EX', 86400);
+};
+
+module.exports = {
+  get, save
+};

package.json

@@ -12,6 +12,7 @@
   "license": "ISC",
   "dependencies": {
     "dotenv": "^4.0.0",
+    "redis": "^2.8.0",
     "request": "^2.83.0",
     "restify": "^6.3.4",
     "restify-clients": "^1.5.2",

twitter.js

@@ -1,3 +1,4 @@
+const cache = require('./cache');
 const Twitter = require('twitter');
 const twitter = new Twitter({
   consumer_key: process.env.TWITTER_CONSUMER_KEY,
@@ -12,9 +13,7 @@ const defaultProfile = {
 
 const cleanHandle = handle => (handle[0] === '@') ? handle.slice(1) : handle;
 
-const getProfileURLs = async handle => {
-  handle = cleanHandle(handle);
-
+const fetchFromTwitter = async handle => {
   return new Promise((resolve, reject) => {
     twitter.get('users/show', {
       user_id: handle,
@@ -32,9 +31,16 @@ const getProfileURLs = async handle => {
         '200x200': user.profile_image_url_https.replace('_normal.', '_200x200.'),
         '400x400': user.profile_image_url_https.replace('_normal.', '_400x400.')
       }
+      // Try and mitigate hitting rate limit
+      cache.save(handle, profileURLs);
       return resolve(profileURLs);
     });
   });
+}
+
+const getProfileURLs = async handle => {
+  handle = cleanHandle(handle);
+  return await cache.get(handle)|| await fetchFromTwitter(handle);
 };
 
 module.exports = {