Mini Shell

module.exports = spawn

var _spawn = require('child_process').spawn
var EventEmitter = require('events').EventEmitter
var npwr = require('./no-progress-while-running.js')

function willCmdOutput (stdio) {
  if (stdio === 'inherit') return true
  if (!Array.isArray(stdio)) return false
  for (var fh = 1; fh <= 2; ++fh) {
    if (stdio[fh] === 'inherit') return true
    if (stdio[fh] === 1 || stdio[fh] === 2) return true
  }
  return false
}

function spawn (cmd, args, options) {
  var cmdWillOutput = willCmdOutput(options && options.stdio)

  if (cmdWillOutput) npwr.startRunning()
  var raw = _spawn(cmd, args, options)
  var cooked = new EventEmitter()

  raw.on('error', function (er) {
    if (cmdWillOutput) npwr.stopRunning()
    er.file = cmd
    cooked.emit('error', er)
  }).on('close', function (code, signal) {
    if (cmdWillOutput) npwr.stopRunning()
    // Create ENOENT error because Node.js v0.8 will not emit
    // an `error` event if the command could not be found.
    if (code === 127) {
      var er = new Error('spawn ENOENT')
      er.code = 'ENOENT'
      er.errno = 'ENOENT'
      er.syscall = 'spawn'
      er.file = cmd
      cooked.emit('error', er)
    } else {
      cooked.emit('close', code, signal)
    }
  })

  cooked.stdin = raw.stdin
  cooked.stdout = raw.stdout
  cooked.stderr = raw.stderr
  cooked.kill = function (sig) { return raw.kill(sig) }

  return cooked
}