child_process = require("child_process")
path          = require("path")
Promise       = require("bluebird")

module.exports = (DockerRemote) -> 

  # Execute system commands and record output.
  #
  # @example
  #   spawn = require("spawn")
  #   spawn("pwd").then (output, exit_code) ->
  #     # do something with output
  #
  class DockerRemote.Spawn

    # @param [Object] options `child_process.spawn` options
    # @option options [String] stdio `pipe`, `ignore`, or `inherit`
    # @option options [String] cwd current working directory of the child process
    #
    constructor: (@options={}) ->

    # @param [String] cmd command to execute
    # @return [ChildProcess]
    #
    childProcess: (cmd, options) ->
      if cmd.split
        cmd = cmd.split(/\s+/)

      child_process.spawn(
        cmd.shift()
        cmd
        options
      )

    # Normalize the cwd option.
    #
    # @param [Object] options `child_process.spawn` options
    #
    resolveCwd: (options) ->
      if options.cwd
        options.cwd = path.normalize(
          "#{process.cwd()}/#{options.cwd}"
        )

    # Promisify `child_process.spawn`.
    #
    # @param [String] cmd command to execute
    # @return [Promise<String,Number>]
    #
    spawn: (cmd, options={}) ->
      options.cwd   ||= @options.cwd
      options.stdio ||= @options.stdio

      @resolveCwd(options)
      
      proc   = @childProcess(cmd, options)
      output = ""

      if proc.stdout
        proc.stdout.on "data", (data) ->
          output += data

        proc.stderr.on "data", (data) ->
          output += data

      new Promise (resolve, reject) =>
        proc.on 'close', (code) =>
          if @options.stdio == "inherit"
            console.log ""
          resolve(output, code)