index.js

var EventEmitter = require('events').EventEmitter
var backoff = require('backoff')

module.exports =
function (createConnection) {
  return function (opts, onConnect) {
    onConnect = 'function' == typeof opts ? opts : onConnect
    opts = 'object' == typeof opts ? opts : {initialDelay: 1e3, maxDelay: 30e3}
    if(!onConnect)
      onConnect = opts.onConnect

    var emitter = new EventEmitter()
    emitter.connected = false
    emitter.reconnect = true

    if(onConnect)
      //use "connection" to match core (net) api.
      emitter.on('connection', onConnect)
    
    var backoffMethod = (backoff[opts.type] || backoff.fibonacci) (opts)

    backoffMethod.on('backoff', function (n, d) {
      emitter.emit('backoff', n, d)
    })

    var args
    function attempt (n, delay) {
      if(emitter.connected) return
      if(!emitter.reconnect) return

      emitter.emit('reconnect', n, delay)
      var con = createConnection.apply(null, args)
      emitter._connection = con

      function onDisconnect (err) {
        emitter.connected = false
        con.removeListener('error', onDisconnect)
        con.removeListener('close', onDisconnect)
        con.removeListener('end'  , onDisconnect)

        //hack to make http not crash.
        //HTTP IS THE WORST PROTOCOL.
        if(con.constructor.name == 'Request')
          con.on('error', function () {})

        //emit disconnect before checking reconnect, so user has a chance to decide not to.
        emitter.emit('disconnect', err)

        if(!emitter.reconnect) return
        try { backoffMethod.backoff() } catch (_) { }
      }

      con
        .on('error', onDisconnect)
        .on('close', onDisconnect)
        .on('end'  , onDisconnect)

      if(opts.immediate || con.constructor.name == 'Request') {
        emitter.connected = true
        emitter.emit('connect', con)
        emitter.emit('connection', con)
        con.once('data', function () {
          //this is the only way to know for sure that data is coming...
          backoffMethod.reset()
        })
      } else {
        con
          .on('connect', function () {
            backoffMethod.reset()
            emitter.connected = true
            if(onConnect)
              con.removeListener('connect', onConnect)
            emitter.emit('connect', con)
            //also support net style 'connection' method.
            emitter.emit('connection', con)
          })
      }
    }

    emitter.connect =
    emitter.listen = function () {
      this.reconnect = true
      if(emitter.connected) return
      backoffMethod.reset()
      backoffMethod.on('ready', attempt)
      args = args || [].slice.call(arguments)
      attempt(0, 0)
      return emitter
    }

    //force reconnection

    emitter.disconnect = function () {
      this.reconnect = false

      if(emitter._connection)
        emitter._connection.end()

      return emitter
    }

    return emitter
  }

}