'use strict'

var Buffer = require('safe-buffer').Buffer
var writeToStream = require('./writeToStream')
var EE = require('events').EventEmitter
var inherits = require('inherits')

function generate (packet) {
  var stream = new Accumulator()
  writeToStream(packet, stream)
  return stream.concat()
}

function Accumulator () {
  this._array = new Array(20)
  this._i = 0
}

inherits(Accumulator, EE)

Accumulator.prototype.write = function (chunk) {
  this._array[this._i++] = chunk
  return true
}

Accumulator.prototype.concat = function () {
  var length = 0
  var lengths = new Array(this._array.length)
  var list = this._array
  var pos = 0
  var i
  var result

  for (i = 0; i < list.length && list[i]; i++) {
    if (typeof list[i] !== 'string') lengths[i] = list[i].length
    else lengths[i] = Buffer.byteLength(list[i])

    length += lengths[i]
  }

  result = Buffer.allocUnsafe(length)

  for (i = 0; i < list.length && list[i]; i++) {
    if (typeof list[i] !== 'string') {
      list[i].copy(result, pos)
      pos += lengths[i]
    } else {
      result.write(list[i], pos)
      pos += lengths[i]
    }
  }

  return result
}

module.exports = generate
