main.js

const http = require('http'),
      req = require('requestretry'),
      Promise = require('bluebird'),
      default_resp = require('./default_resp.json'),
      imgur = require('./sources/imgur.js'),
      giphy = require('./sources/giphy.js'),
      async = require('async'),
      path = require('path'),
      fs = require('fs')

var DEBUG = process.env.DEBUG == "true" || false
var port = 3000
if (process.argv.length > 2) {
  port = process.argv[2]
}

var sources = initSources()

const requestHandler = function (request, response) {
  if(request.method == "POST") {
    var body = "";
    request.on('data', function (chunk) {
      body += chunk;
    });
    request.on('end', function () {
      var contents = getContents(body)
      var fullUrl = decodeURIComponent(contents.response_url)
      picResponse(decodeURIComponent(contents.text), request).then(function(pic){
        req.post(fullUrl, {body:pic, json:true, maxAttempts: 5 },function(err,httpResponse,body){
          if(err || httpResponse.statusCode >= 300){
            console.log('----')
            console.log("Errors replying:")
            console.log("Pic: ", pic)
            console.log("Reply URL: ", fullUrl)
            console.log(err)
            console.log(httpResponse.statusCode)
            console.log(body)
            console.log('----')
          }
        })
      })
    })
  }
  if(request.url.includes("/images/")) {
    return sendStaticImages(response, request)
  }
  console.log(request.method, " on ", request.url, " from ", request.connection.remoteAddress)
  response.setHeader('content-type', 'application/json');
  response.end(JSON.stringify(default_resp))
}

const server = http.createServer(requestHandler)

server.listen(port, function (err) {
  if (err) {
    return console.log('something bad happened', err)
  }

  console.log('server is listening on', port)
})

function getContents(body) {
  var parts = body.split('&')
  var contents = {}
  parts.forEach(function(item) {
    var pair = item.split("=")
    contents[pair[0]] = pair[1]
  }, this);
  return contents
}

//NOTE: the request object is here because we need to attribute giphy images... kinda dirty.
function picResponse(terms_concat, request) {
  var terms = terms_concat.split('+')
  return getOptions(terms).then(function(options){
    debug("Got " + options.length + " Options")
    var picData = selectRandom(options)
    debug("Selected: " + JSON.stringify(picData))
    var pic = picData.pic
    var response = {
      "response_type": "in_channel",
      "text":picData.pic
    }
    debug("Response data: " + JSON.stringify(response))
    var attach = {};
    if(picData.source == "giphy"){
      debug("From giphy")
      attach = {
        "fallback":"Powered by " + picData.source,
        "image_url": "http://" + request.headers.host + "/images/poweredByGiphy.png"
      }
    } else if(picData.source == "imgur") {
      attach = {
        "fallback":"Don't relly know what this is.",
        "color":"#85bf25",
        "text":picData.post
      }
    }
    response.attachments = [attach]
    return response
  })
}

function getOptions(terms){
  return new Promise(function(resolve, reject){
    async.concat(sources, function(source, callback){
      source.search(terms).then(function(results){
        callback(null, results)
      }).catch(function(error) {
        console.log(error)
        console.log('Source: ', source.name, ' had a problem with terms: ', terms)
        callback(null, [])
      })
    }, function(err, results){
      if(err) {
        console.log("Error getting images from sources:", err)
        return reject(err)
      }
      resolve(results)
    })
  })
}

function initSources(){
  return [
    new imgur.Imgur(),
    new giphy.Giphy(),
  ]
}

function selectRandom(options){
  var total = options.length
  if(total == 0){
    return {"source":"static", "pic": "http://i.imgur.com/4AjVHdR.png"}
  }
  var optionIndex = Math.floor(Math.random() * total)
  debug("Choosing index: " + optionIndex + " of Total: " + total)
  return options[optionIndex]
}

function sendStaticImages(response, request) {
  response.statusCode = 200
  var fileLoc = path.resolve("./")
  fileLoc = path.join(fileLoc, request.url)
  return fs.readFile(fileLoc, function(err, data){
    if(err) {
      response.writeHead(404, 'Not Found');
      response.write('404: File Not Found!');
      return response.end();
    }
    response.write(data)
    return response.end();
  })
}

function debug(msg) {
  if(DEBUG){
    console.log(msg)
  }
}