server.js

// server.js

// Node.js implementation of slackline – https://github.com/ernesto-jimenez/slackline


// BASE SETUP
// ========================================================================================

// required modules
var settings  = require ('./settings');
var express   = require('express');
var bodyParser  = require('body-parser');
var http    = require('http');
var https   = require('https');
var querystring = require('querystring');
var request   = require('request');
var crypto    = require('crypto');

// create an instance of express
var app = express();

// configure the app to use bodyParser()
// this will allow us to interpret the data from a POST
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());

var port = process.env.PORT || 8080;


// ROUTES
// ========================================================================================

var router = express.Router();

// test route to make sure everything is working
router.get('/', function(req, res) {
  res.json({ message: 'hooray! welcome to slackline!' });
});

router.all('/bridge', function(req, res) {
  var username = req.body.user_name;
  var userid = req.body.user_id;
  var text = req.body.text;
  var target_domain = req.query.domain;
  var target_hook_token = req.query.token;

  // to avoid infinite loops, don't post messages generated by slackbot
  if (username == "slackbot") {
    console.log("don't reflect this message; it's from the other channel!")
    res.end('Message forwarded!');
    return
  } else {
    getHash(userid, target_domain, function(err, email_hash){
      fixMentions(text, target_domain, function(err, cleanText){
        sendPost(email_hash, username, cleanText, target_domain, target_hook_token);
      });
    });

    // TO DO: only fire success message when sendPost actually finishes (via a callback)
    res.end('Message forwarded!');
  };
});

app.use(router);


// START THE SERVER
// ========================================================================================

app.listen(port);
console.log('slackline is running on port ' + port);


// FUNCTIONS
// ========================================================================================


var mentionMap = {}

// takes a raw Slack message as an input, returns a cleaned string with any @ mentions converted to the relevant usernames
function fixMentions(text, target_domain, next){
  var strText = text;
  var userPattern = /<@([^>]+)>/igm;
  var userArray = strText.match(userPattern);

  if (userArray) {
    var counter = 0;

    userArray.forEach(function(strUseridRaw){
      if (mentionMap[strUseridRaw]) {
        strText = strText.replace(strUseridRaw, '@' + mentionMap[strUseridRaw]);
        counter += 1;
        if (counter == (userArray.length)) {
          next(null, strText);
        }
      } else {
        var strUserid = strUseridRaw.substring(2, strUseridRaw.length -1);

        // get the sender's domain from settings.js
        var referrer_domain = settings.domainReferrer[target_domain];

        // use the sender's domain and userid to grab their user info from the Slack API
        var url = 'https://slack.com/api/users.info?token=' + settings.tokens[referrer_domain] + '&user=' + strUserid;

        https.get(url, function(res) {
          var body = '';

          res.on('data', function(chunk) {
            body += chunk;
          });

          res.on('end', function() {
            var userResponse = JSON.parse(body);
            var username = userResponse.user.name;
            mentionMap[strUseridRaw] = username;
            strText = strText.replace(strUseridRaw, '@' + username);
            counter += 1;
            if (counter == (userArray.length)) {
              next(null, strText);
            }
          });
        }).on('error', function(e) {
          console.log('Got error: ' + e);
        });
      }
    });
  } else {
    next(null, text);
  };
};


// cache of hashed email addresses, used for Gravatar URLs
var emailMap = {};

// calculate a hash of a user's email address based on userid. if that userid already exists in the cache, use the cached value.
// pass hash to the callback
function getHash(userid, target_domain, next) {

  if (emailMap[userid]) {
    var email_hash = emailMap[userid];
    next(null, email_hash);
  } else {
    // get the sender's domain from settings.js
    var referrer_domain = settings.domainReferrer[target_domain];

    // use the sender's domain and userid to grab their user info from the Slack API
    var url = 'https://slack.com/api/users.info?token=' + settings.tokens[referrer_domain] + '&user=' + userid;

    https.get(url, function(res) {
      var body = '';

      res.on('data', function(chunk) {
        body += chunk;
      });

      res.on('end', function() {
        var userResponse = JSON.parse(body);
        var email_hash = crypto.createHash('md5').update(userResponse.user.profile.email).digest('hex');
        emailMap[userid] = email_hash;
        next(null, email_hash);
      });
    }).on('error', function(e) {
      console.log('Got error: ' + e);
    });
  };
};


// Send the forwarded message as a POST to the target Slack instance
function sendPost(email_hash, username, text, target_domain, target_hook_token) {
  var options = {
    uri: 'https://' + target_domain + settings.postUrl + target_hook_token,
    method: 'POST',
    json: {
      'username' : username,
      'text' : text,
      'icon_url' : 'http://www.gravatar.com/avatar/' + email_hash
    }
  };

  request(options, function(error, response, body) {
    if(!error && response.statusCode == 200) {
      console.log('Success!');
    } else {
      console.log(response);
    }
  });
};