Added redis. Chat io msg to redis list.

api/redis.js

@@ -0,0 +1,39 @@
+const redis = require("redis")
+const client = redis.createClient()
+
+
+const addMessage = message => {
+  const json = JSON.stringify(message);
+  client.rpush("messages", json)
+
+  return message
+}
+
+const history = (skip=0, take=20) => {
+  skip = (1 + skip) * -1     // negate to get FIFO
+  return new Promise((resolve, reject) => client.lrange("messages", (skip * take), skip, (err, data) => {
+    if (err) {
+      console.log(err);
+      reject(err);
+    }
+
+    data = data.map(data => JSON.parse(data));
+    resolve(data);
+  }))
+}
+
+const clearHistory = () => {
+  return new Promise((resolve, reject) => client.del("messages", (err, success) => {
+    if (err) {
+      console.log(err);
+      reject(err);
+    }
+    resolve(success == 1 ? true : false);
+  }))
+}
+
+module.exports = {
+  addMessage,
+  history,
+  clearHistory
+};