Add minimal 'echo' facebook bot

bot/facebook/index.js

@@ -0,0 +1,51 @@
+const {text, json, createError} = require('micro')
+const {get, post, withNamespace} = require('microrouter')
+
+const fbParser = require('claudia-bot-builder/lib/facebook/parse')
+const fbReply = require('claudia-bot-builder/lib/facebook/reply')
+const fbValidate = require('claudia-bot-builder/lib/facebook/validate-integrity')
+const fbTemplate = require('claudia-bot-builder/lib/facebook/format-message')
+
+const verifyToken = req => {
+  if (req.query['hub.verify_token'] === process.env.FB_VERIFY_TOKEN) {
+    return req.query['hub.challenge']
+  }
+  console.info(
+    `Your Facebook Access Token (that Facebook will echo back to you as part of callback URL verification): ${
+      process.env.FB_VERIFY_TOKEN
+    }`
+  )
+  return 'INVALID TOKEN'
+}
+
+const fbMessage = async req => {
+  req.env = {facebookAppSecret: process.env.FB_APP_SECRET}
+  req.rawBody = await text(req)
+  const data = await json(req)
+  const message = data.entry.map(
+    entry => entry.messaging.map(message => fbParser(message))[0]
+  )[0]
+
+  const isValid = fbValidate(req) && message.type === 'facebook'
+
+  return isValid ? message : false
+}
+
+const respond = async (req, res) => {
+  const message = await fbMessage(req)
+  if (message) {
+    const recipient = message.sender
+    const replyMessage = new fbTemplate.Text(
+      `You've said: "${message.text}"`
+    ).get()
+
+    await fbReply(recipient, replyMessage, process.env.FB_ACCESS_TOKEN)
+
+    res.end()
+  } else {
+    throw createError(400, 'Invalid message signature.')
+  }
+}
+
+const fbApi = withNamespace('/api/v1/facebook')
+module.exports = fbApi(get('/', verifyToken), post('/', respond))