feat: add support for bot commands

This allows the bot to listen to predefined commands, so that we can
call his output in a public channel.

lib/commands.js

@@ -0,0 +1,4 @@
+module.exports = [
+  'what needs review?',
+  '!review',
+]

lib/helpers.js

@@ -1,3 +1,5 @@
+const commands = require('./commands')
+
 const isDirectMessage = function isDirectMessage (msg) {
   // slack direct messages channel id start with D
   return msg.type === 'message' && msg.channel.charAt(0) === 'D'
@@ -7,4 +9,13 @@ const isBotMessage = function isBotMessage (msg) {
   return msg.subtype && msg.subtype === 'bot_message'
 }
 
-module.exports = { isDirectMessage, isBotMessage }
+const isMessage = function isMessage (msg) {
+  return msg.type === 'message'
+}
+
+// for now all commands execute the same operation
+const isBotCommand = function isBotCommand (msg) {
+  return commands.some((command) => msg.text === command)
+}
+
+module.exports = { isDirectMessage, isBotMessage, isMessage, isBotCommand }

lib/server.js

@@ -1,6 +1,11 @@
 const Slackbot = require('slackbots')
 const pullhub = require('pullhub')
-const { isDirectMessage, isBotMessage } = require('./helpers')
+const {
+  isDirectMessage,
+  isBotMessage,
+  isMessage,
+  isBotCommand
+} = require('./helpers')
 
 module.exports = function server () {
   const env = process.env
@@ -32,9 +37,8 @@ module.exports = function server () {
   })
 
   bot.on('message', (data) => {
-    if (isDirectMessage(data) && !isBotMessage(data)) {
-      console.log(data)
-
+    if ((isMessage(data) && isBotCommand(data)) ||
+      (isDirectMessage(data) && !isBotMessage(data))) {
       getPullRequests()
         .then(buildMessage)
         .then((message) => {