This is a implementation of a bot for messenger. It uses a webhook that listen to POST event on a facebook page (ie : when a user send a message to that page), and alert a node.js server. The server then use facebook send API to send back the appropriate answer, that will of course be powered by some mystic pythonic algorithms.

Frist things first, you should have a look at this page, carefully craft by facebook devs : https://developers.facebook.com/docs/messenger-platform/quickstart

• We need a "real url" for our webhook (meaning not a localhost), because facebook will only accept verified urls. Ngrok is the tool for this purpose. Download ngrok there : https://ngrok.com. Put the binary in usr/local/bin or your equivalent directory linked to your $PATH environment variable. Then use from anywhere in the terminal ngrok http 8888 to set up an url such as https://55feb1ab.ngrok.io. This will be your reverse proxy for your localhost.
• Download nodemon with the command : npm install nodemon -g, so that you won't have to relauch the node server every time (better than re-starting with node index.js everytime)
• Launch the server using the command : nodemon index.js. You can update it anytime with the command rs (restart server)
• Type npm install from the working directory in your terminal to get the node_modules needed for our node.js server.

• Create a facebook app there : https://developers.facebook.com. Then go to your app settings and under Products add a product and select Messenger and Webhooks
• Go to the Products/webhooks tab and set up a webhook at the ngrok url with any verify_token. Subscribe to message_deliveries, messages, messaging_optins, messaging_postbacks fields
• Go to the Products/Messenger tab and get your page access token by selecting the facebook page you want to use (in Token Generation section).
• Still on the Products/Messenger tab, subscribe the app to the page in the Messenger tab, in the Webhooks section.
• To finish with, create a config.js file such as below and update it with the corresponding parameters. Carefully choose your python path (use which python in the terminal to know) and your python repository path where your predict.py script is. You should use port 8888.

var config = {};

config.FB_VERIFY_TOKEN = "VERIFY_TOKEN";
config.FB_PAGE_TOKEN="ACCESS_TOKEN";
config.SERVER_URL = "WEBHOOK_URL";
config.port = 8888;

config.pythonScriptsPath = "PATH_TO_PYTHON_SCRIPT";
config.pythonPath = "PATH_TO_PYTHON_REPO"

module.exports = config;

• make_faqjson.js generate faq_step.json and then faq.json, that is used in make_dispatcher_tree.js to make the tree structure.
• make_dispatcher_tree.js generate the code for the quick replies used for the tree structure, using faq.json. This code is to be copy pasted in the button-controller.js.
• make_read_here.js generate the code for the read here button on the generic template pushed to the user, using link2answer.json, the scraping result. link2answer.json is formated in python so that it match the 320 characters limits, and it extract the link and image of the FAQ. This code is to be copy pasted in the main-controller in the receivedPostback function.
• link2newlink.json is mainly used in make_dispatcher_tree.js>make_generic_node function to update old links, so that it will works with the payload of the link2answer.json file (that has only new urls as it was just scraped)
• motifs.json is used in make_dispatcher_tree.js>make_quickreply_node function to update the categories exceeding 20 characters (for complying to the fb messenger API restriction for quick reply items.)

• request are incoming in index.js. This is where we instanciate the app and where we listen to facebook messenger event though a webhook. Incoming message can be of two types: ** postback, that are the payload of our button & generic templates. Those are handled in mainCtrl.receivedPostback function. ** message, that are either a text message for the user, or the payload of a quick reply. Those are handle in 'mainCtrl.receivedMessage' function.
• main-controller.js is mainly composed of four elements: ** gettingStarted, greetingText & menu that are three function that need to send a POST request once in order to set up the getting started button, the menu button... ** receivedMessage & receivedPostback, as mention earlier (note the read_here buttons payload in the receivedPostback function) ** sendCallback, that is used as a callback that triggers the sendAPI for python-controller and button-controller. sendHelpMessage, sendTextMessage, sendButtonMessage, sendQuickReply, etc... are functions that parse the output to the fb json format. ** callSendAPI, to finish with, is the function that actually call the fb send API.
• button-controller.js is handling quick reply's payload
• python-controller.js is handling machine learning features.

• payload are limited to 1000 characters
• text is limited to 320 characters
• quick replies are limited to 20 characters

• heroku create senditsfrbot, heroku logs, heroku ps, heroku run bash, git add ., git commit -m 'your_commit', git push heroku master
• pos_tagging not working because of compilation in 84 format (cf tree tagger), okk
• nltk_data a downloader (stopwords), cf http://stackoverflow.com/questions/13965823/resource-corpora-wordnet-not-found-on-heroku
• requirement.txt is used to install python dependencies
• package.json is used to install node dependencies
• Procfile is stating how to start our node server (node index.js)
• need SSL https:// for use as a facebook messenger webhook. If hosted on example.herokuapp.com, it will work, but if not, we need to pay for a SSL subscription.