/**
 * Service which will listen for a Github webhook, fired on push.
 * This service can be used to rebuild / restart the app automatically
 * when new code is pushed.
 */

var crypto = require('crypto')
var exec = require('child_process').exec
var path = require('path')

function OKWebhook (options) {
  if (!(this instanceof OKWebhook)) return new OKWebhook(options)
  options = options || {}
  if (!options.express)
    throw new Error('Express not provided to OKWebhook');
  if (!options.config)
    throw new Error('Configuration not provided to OKWebhook');
  if (options.config.active && !options.config.secret)
    throw new Error('Github secret not provided to OKWebhook');
  if (options.config.active && !options.config.command)
    throw new Error('Build command not provided to OKWebhook');

  var express = options.express
  var router = express.Router()
  var config = options.config
  
  var secret = config.secret
  var command = config.command

  router.get('/', function (req, res) {
    res.send('GET not supported')
  })

  router.post('/', getBody, function (req, res) {
    if (!config.active)
      return
    console.log("OKWebhook received push")
    var event = req.headers['x-github-event']
    if (event !== "push") {
      return res.sendStatus(500)
    }
    var sig = req.headers['x-hub-signature'].split('=')[1]
    var text = req.rawBody
    var hash = crypto.createHmac('sha1', secret).update(text).digest('hex')
    if (hash !== sig) {
      return res.sendStatus(500)
    }
    res.sendStatus(200)
    var cwd = path.dirname(command)
    exec(command, { cwd: cwd }, function(err, stdout, stderr){
      // may not fire if process was restarted..
      console.log(process.env)
      console.log(stdout)
    })
  })

  function getBody (req, res, next) {
    req.rawBody = ''
    // req.setEncoding('utf8')

    req.on('data', function(chunk) { 
      req.rawBody += chunk
    })

    req.on('end', function() {
      try {
        req.body = JSON.parse(req.rawBody)
      } catch (e) {
        return res.sendStatus(500)
      }
      next()
    })
  }

  this._router = router
}

OKWebhook.prototype.middleware = function () {
  return this._router
}

module.exports = OKWebhook