const assign = require('./lib/assign')
const Command = require('./lib/command')
const Completion = require('./lib/completion')
const Parser = require('yargs-parser')
const path = require('path')
const Usage = require('./lib/usage')
const Validation = require('./lib/validation')
const Y18n = require('y18n')
const objFilter = require('./lib/obj-filter')
const setBlocking = require('set-blocking')

var exports = module.exports = Yargs
function Yargs (processArgs, cwd, parentRequire) {
  processArgs = processArgs || [] // handle calling yargs().

  const self = {}
  var command = null
  var completion = null
  var groups = {}
  var output = ''
  var preservedGroups = {}
  var usage = null
  var validation = null

  const y18n = Y18n({
    directory: path.resolve(__dirname, './locales'),
    updateFiles: false
  })

  if (!cwd) cwd = process.cwd()

  self.$0 = process.argv
    .slice(0, 2)
    .map(function (x, i) {
      // ignore the node bin, specify this in your
      // bin file with #!/usr/bin/env node
      if (i === 0 && /\b(node|iojs)(\.exe)?$/.test(x)) return
      var b = rebase(cwd, x)
      return x.match(/^(\/|([a-zA-Z]:)?\\)/) && b.length < x.length ? b : x
    })
    .join(' ').trim()

  if (process.env._ !== undefined && process.argv[1] === process.env._) {
    self.$0 = process.env._.replace(
      path.dirname(process.execPath) + '/', ''
    )
  }

  // use context object to keep track of resets, subcommand execution, etc
  // submodules should modify and check the state of context as necessary
  const context = { resets: -1, commands: [], files: [] }
  self.getContext = function () {
    return context
  }

  // puts yargs back into an initial state. any keys
  // that have been set to "global" will not be reset
  // by this action.
  var options
  self.resetOptions = self.reset = function (aliases) {
    context.resets++
    aliases = aliases || {}
    options = options || {}
    // put yargs back into an initial state, this
    // logic is used to build a nested command
    // hierarchy.
    var tmpOptions = {}
    tmpOptions.global = options.global ? options.global : []
    tmpOptions.configObjects = options.configObjects ? options.configObjects : []

    // if a key has been set as a global, we
    // do not want to reset it or its aliases.
    var globalLookup = {}
    tmpOptions.global.forEach(function (g) {
      globalLookup[g] = true
      ;(aliases[g] || []).forEach(function (a) {
        globalLookup[a] = true
      })
    })

    // preserve groups containing global keys
    preservedGroups = Object.keys(groups).reduce(function (acc, groupName) {
      var keys = groups[groupName].filter(function (key) {
        return key in globalLookup
      })
      if (keys.length > 0) {
        acc[groupName] = keys
      }
      return acc
    }, {})
    // groups can now be reset
    groups = {}

    var arrayOptions = [
      'array', 'boolean', 'string', 'requiresArg', 'skipValidation',
      'count', 'normalize', 'number'
    ]

    var objectOptions = [
      'narg', 'key', 'alias', 'default', 'defaultDescription',
      'config', 'choices', 'demandedOptions', 'demandedCommands', 'coerce'
    ]

    arrayOptions.forEach(function (k) {
      tmpOptions[k] = (options[k] || []).filter(function (k) {
        return globalLookup[k]
      })
    })

    objectOptions.forEach(function (k) {
      tmpOptions[k] = objFilter(options[k], function (k, v) {
        return globalLookup[k]
      })
    })

    tmpOptions.envPrefix = options.envPrefix
    options = tmpOptions

    // if this is the first time being executed, create
    // instances of all our helpers -- otherwise just reset.
    usage = usage ? usage.reset(globalLookup) : Usage(self, y18n)
    validation = validation ? validation.reset(globalLookup) : Validation(self, usage, y18n)
    command = command ? command.reset() : Command(self, usage, validation)
    if (!completion) completion = Completion(self, usage, command)

    strict = false
    completionCommand = null
    output = ''
    exitError = null
    hasOutput = false
    self.parsed = false

    return self
  }
  self.resetOptions()

  // temporary hack: allow "freezing" of reset-able state for parse(msg, cb)
  var frozen
  function freeze () {
    frozen = {}
    frozen.options = options
    frozen.configObjects = options.configObjects.slice(0)
    frozen.exitProcess = exitProcess
    frozen.groups = groups
    usage.freeze()
    validation.freeze()
    command.freeze()
    frozen.strict = strict
    frozen.completionCommand = completionCommand
    frozen.output = output
    frozen.exitError = exitError
    frozen.hasOutput = hasOutput
    frozen.parsed = self.parsed
  }
  function unfreeze () {
    options = frozen.options
    options.configObjects = frozen.configObjects
    exitProcess = frozen.exitProcess
    groups = frozen.groups
    output = frozen.output
    exitError = frozen.exitError
    hasOutput = frozen.hasOutput
    self.parsed = frozen.parsed
    usage.unfreeze()
    validation.unfreeze()
    command.unfreeze()
    strict = frozen.strict
    completionCommand = frozen.completionCommand
    parseFn = null
    parseContext = null
    frozen = undefined
  }

  self.boolean = function (bools) {
    options.boolean.push.apply(options.boolean, [].concat(bools))
    return self
  }

  self.array = function (arrays) {
    options.array.push.apply(options.array, [].concat(arrays))
    return self
  }

  self.nargs = function (key, n) {
    if (typeof key === 'object') {
      Object.keys(key).forEach(function (k) {
        self.nargs(k, key[k])
      })
    } else {
      options.narg[key] = n
    }
    return self
  }

  self.number = function (numbers) {
    options.number.push.apply(options.number, [].concat(numbers))
    return self
  }

  self.choices = function (key, values) {
    if (typeof key === 'object') {
      Object.keys(key).forEach(function (k) {
        self.choices(k, key[k])
      })
    } else {
      options.choices[key] = (options.choices[key] || []).concat(values)
    }
    return self
  }

  self.normalize = function (strings) {
    options.normalize.push.apply(options.normalize, [].concat(strings))
    return self
  }

  self.config = function (key, msg, parseFn) {
    // allow to pass a configuration object
    if (typeof key === 'object') {
      options.configObjects = (options.configObjects || []).concat(key)
      return self
    }

    // allow to provide a parsing function
    if (typeof msg === 'function') {
      parseFn = msg
      msg = null
    }

    key = key || 'config'
    self.describe(key, msg || usage.deferY18nLookup('Path to JSON config file'))
    ;(Array.isArray(key) ? key : [key]).forEach(function (k) {
      options.config[k] = parseFn || true
    })
    return self
  }

  self.example = function (cmd, description) {
    usage.example(cmd, description)
    return self
  }

  self.command = function (cmd, description, builder, handler) {
    command.addHandler(cmd, description, builder, handler)
    return self
  }

  self.commandDir = function (dir, opts) {
    const req = parentRequire || require
    command.addDirectory(dir, self.getContext(), req, require('get-caller-file')(), opts)
    return self
  }

  self.string = function (strings) {
    options.string.push.apply(options.string, [].concat(strings))
    return self
  }

  // The 'defaults' alias is deprecated. It will be removed in the next major version.
  self.default = self.defaults = function (key, value, defaultDescription) {
    if (typeof key === 'object') {
      Object.keys(key).forEach(function (k) {
        self.default(k, key[k])
      })
    } else {
      if (defaultDescription) options.defaultDescription[key] = defaultDescription
      if (typeof value === 'function') {
        if (!options.defaultDescription[key]) options.defaultDescription[key] = usage.functionDescription(value)
        value = value.call()
      }
      options.default[key] = value
    }
    return self
  }

  self.alias = function (x, y) {
    if (typeof x === 'object') {
      Object.keys(x).forEach(function (key) {
        self.alias(key, x[key])
      })
    } else {
      options.alias[x] = (options.alias[x] || []).concat(y)
    }
    return self
  }

  self.coerce = function (key, fn) {
    if (typeof key === 'object' && !Array.isArray(key)) {
      Object.keys(key).forEach(function (k) {
        self.coerce(k, key[k])
      })
    } else {
      [].concat(key).forEach(function (k) {
        options.coerce[k] = fn
      })
    }
    return self
  }

  self.count = function (counts) {
    options.count.push.apply(options.count, [].concat(counts))
    return self
  }

  // deprecated: the demand API is too overloaded, and is being
  // deprecated in favor of .demandCommand() .demandOption().
  self.demand = self.required = self.require = function (keys, max, msg) {
    // you can optionally provide a 'max' key,
    // which will raise an exception if too many '_'
    // options are provided.
    if (Array.isArray(max)) {
      max.forEach(function (key) {
        self.demandOption(key, msg)
      })
      max = Infinity
    } else if (typeof max !== 'number') {
      msg = max
      max = Infinity
    }

    if (typeof keys === 'number') {
      self.demandCommand(keys, max, msg)
    } else if (Array.isArray(keys)) {
      keys.forEach(function (key) {
        self.demandOption(key, msg)
      })
    } else {
      if (typeof msg === 'string') {
        self.demandOption(keys, msg)
      } else if (msg === true || typeof msg === 'undefined') {
        self.demandOption(keys)
      }
    }

    return self
  }

  self.demandOption = function (key, msg) {
    if (Array.isArray(key)) {
      key.forEach(function (key) {
        self.demandOption(key, msg)
      })
    } else {
      if (typeof msg === 'string') {
        options.demandedOptions[key] = { msg: msg }
      // allow edge-case of options: {a: {demand: true}, b: {demand: false}}
      } else if (msg === true || typeof msg === 'undefined') {
        options.demandedOptions[key] = { msg: undefined }
      }
    }

    return self
  }

  self.demandCommand = function (min, max, minMsg, maxMsg) {
    if (typeof max !== 'number') {
      minMsg = max
      max = Infinity
    }

    options.demandedCommands._ = {
      min: min,
      max: max,
      minMsg: minMsg,
      maxMsg: maxMsg
    }

    return self
  }

  self.getDemandedOptions = function () {
    return options.demandedOptions
  }

  self.getDemandedCommands = function () {
    return options.demandedCommands
  }

  self.requiresArg = function (requiresArgs) {
    options.requiresArg.push.apply(options.requiresArg, [].concat(requiresArgs))
    return self
  }

  self.skipValidation = function (skipValidations) {
    options.skipValidation.push.apply(options.skipValidation, [].concat(skipValidations))
    return self
  }

  self.implies = function (key, value) {
    validation.implies(key, value)
    return self
  }

  self.conflicts = function (key1, key2) {
    validation.conflicts(key1, key2)
    return self
  }

  self.usage = function (msg, opts) {
    if (!opts && typeof msg === 'object') {
      opts = msg
      msg = null
    }

    usage.usage(msg)

    if (opts) self.options(opts)

    return self
  }

  self.epilogue = self.epilog = function (msg) {
    usage.epilog(msg)
    return self
  }

  self.fail = function (f) {
    usage.failFn(f)
    return self
  }

  self.check = function (f) {
    validation.check(f)
    return self
  }

  self.describe = function (key, desc) {
    if (typeof key === 'object') {
      Object.keys(key).forEach(function (k) {
        options.key[k] = true
      })
    } else {
      options.key[key] = true
    }
    usage.describe(key, desc)
    return self
  }

  self.global = function (globals) {
    options.global.push.apply(options.global, [].concat(globals))
    return self
  }

  self.pkgConf = function (key, path) {
    var conf = null

    var obj = pkgUp(path)

    // If an object exists in the key, add it to options.configObjects
    if (obj[key] && typeof obj[key] === 'object') {
      conf = obj[key]
      options.configObjects = (options.configObjects || []).concat(conf)
    }

    return self
  }

  var pkgs = {}
  function pkgUp (path) {
    var npath = path || '*'
    if (pkgs[npath]) return pkgs[npath]
    const readPkgUp = require('read-pkg-up')

    var obj = {}
    try {
      obj = readPkgUp.sync({
        cwd: path || require('require-main-filename')(parentRequire || require),
        normalize: false
      })
    } catch (noop) {}

    pkgs[npath] = obj.pkg || {}
    return pkgs[npath]
  }

  var parseFn = null
  var parseContext = null
  self.parse = function (args, shortCircuit, _parseFn) {
    // a context object can optionally be provided, this allows
    // additional information to be passed to a command handler.
    if (typeof shortCircuit === 'object') {
      parseContext = shortCircuit
      shortCircuit = _parseFn
    }

    // by providing a function as a second argument to
    // parse you can capture output that would otherwise
    // default to printing to stdout/stderr.
    if (typeof shortCircuit === 'function') {
      parseFn = shortCircuit
      shortCircuit = null
    }
    // completion short-circuits the parsing process,
    // skipping validation, etc.
    if (!shortCircuit) processArgs = args

    freeze()
    if (parseFn) exitProcess = false

    var parsed = parseArgs(args, shortCircuit)
    if (parseFn) parseFn(exitError, parsed, output)
    unfreeze()

    return parsed
  }

  self._hasParseCallback = function () {
    return !!parseFn
  }

  self.option = self.options = function (key, opt) {
    if (typeof key === 'object') {
      Object.keys(key).forEach(function (k) {
        self.options(k, key[k])
      })
    } else {
      if (typeof opt !== 'object') {
        opt = {}
      }

      options.key[key] = true // track manually set keys.

      if (opt.alias) self.alias(key, opt.alias)

      var demand = opt.demand || opt.required || opt.require

      if (demand) {
        self.demand(key, demand)
      }

      if ('demandOption' in opt) {
        self.demandOption(key, opt.demandOption)
      }

      if ('config' in opt) {
        self.config(key, opt.configParser)
      }

      if ('default' in opt) {
        self.default(key, opt.default)
      }

      if ('nargs' in opt) {
        self.nargs(key, opt.nargs)
      }

      if ('normalize' in opt) {
        self.normalize(key)
      }

      if ('choices' in opt) {
        self.choices(key, opt.choices)
      }

      if ('coerce' in opt) {
        self.coerce(key, opt.coerce)
      }

      if ('group' in opt) {
        self.group(key, opt.group)
      }

      if (opt.global) {
        self.global(key)
      }

      if (opt.boolean || opt.type === 'boolean') {
        self.boolean(key)
        if (opt.alias) self.boolean(opt.alias)
      }

      if (opt.array || opt.type === 'array') {
        self.array(key)
        if (opt.alias) self.array(opt.alias)
      }

      if (opt.number || opt.type === 'number') {
        self.number(key)
        if (opt.alias) self.number(opt.alias)
      }

      if (opt.string || opt.type === 'string') {
        self.string(key)
        if (opt.alias) self.string(opt.alias)
      }

      if (opt.count || opt.type === 'count') {
        self.count(key)
      }

      if (opt.defaultDescription) {
        options.defaultDescription[key] = opt.defaultDescription
      }

      if (opt.skipValidation) {
        self.skipValidation(key)
      }

      var desc = opt.describe || opt.description || opt.desc
      if (desc) {
        self.describe(key, desc)
      }

      if (opt.requiresArg) {
        self.requiresArg(key)
      }
    }

    return self
  }
  self.getOptions = function () {
    return options
  }

  self.group = function (opts, groupName) {
    var existing = preservedGroups[groupName] || groups[groupName]
    if (preservedGroups[groupName]) {
      // the preserved group will be moved to the set of explicitly declared
      // groups
      delete preservedGroups[groupName]
    }

    var seen = {}
    groups[groupName] = (existing || []).concat(opts).filter(function (key) {
      if (seen[key]) return false
      return (seen[key] = true)
    })
    return self
  }
  self.getGroups = function () {
    // combine explicit and preserved groups. explicit groups should be first
    return assign(groups, preservedGroups)
  }

  // as long as options.envPrefix is not undefined,
  // parser will apply env vars matching prefix to argv
  self.env = function (prefix) {
    if (prefix === false) options.envPrefix = undefined
    else options.envPrefix = prefix || ''
    return self
  }

  self.wrap = function (cols) {
    usage.wrap(cols)
    return self
  }

  var strict = false
  self.strict = function () {
    strict = true
    return self
  }
  self.getStrict = function () {
    return strict
  }

  self.showHelp = function (level) {
    if (!self.parsed) parseArgs(processArgs) // run parser, if it has not already been executed.
    usage.showHelp(level)
    return self
  }

  var versionOpt = null
  self.version = function (opt, msg, ver) {
    if (arguments.length === 0) {
      ver = guessVersion()
      opt = 'version'
    } else if (arguments.length === 1) {
      ver = opt
      opt = 'version'
    } else if (arguments.length === 2) {
      ver = msg
    }

    versionOpt = opt
    msg = msg || usage.deferY18nLookup('Show version number')

    usage.version(ver || undefined)
    self.boolean(versionOpt)
    self.global(versionOpt)
    self.describe(versionOpt, msg)
    return self
  }

  function guessVersion () {
    var obj = pkgUp()

    return obj.version || 'unknown'
  }

  var helpOpt = null
  var useHelpOptAsCommand = false // a call to .help() will enable this
  self.addHelpOpt = self.help = function (opt, msg, addImplicitCmd) {
    // argument shuffle
    if (arguments.length === 0) {
      useHelpOptAsCommand = true
    } else if (arguments.length === 1) {
      if (typeof opt === 'boolean') {
        useHelpOptAsCommand = opt
        opt = null
      } else {
        useHelpOptAsCommand = true
      }
    } else if (arguments.length === 2) {
      if (typeof msg === 'boolean') {
        useHelpOptAsCommand = msg
        msg = null
      } else {
        useHelpOptAsCommand = true
      }
    } else {
      useHelpOptAsCommand = Boolean(addImplicitCmd)
    }
    // use arguments, fallback to defaults for opt and msg
    helpOpt = opt || 'help'
    self.boolean(helpOpt)
    self.global(helpOpt)
    self.describe(helpOpt, msg || usage.deferY18nLookup('Show help'))
    return self
  }

  self.showHelpOnFail = function (enabled, message) {
    usage.showHelpOnFail(enabled, message)
    return self
  }

  var exitProcess = true
  self.exitProcess = function (enabled) {
    if (typeof enabled !== 'boolean') {
      enabled = true
    }
    exitProcess = enabled
    return self
  }
  self.getExitProcess = function () {
    return exitProcess
  }

  var completionCommand = null
  self.completion = function (cmd, desc, fn) {
    // a function to execute when generating
    // completions can be provided as the second
    // or third argument to completion.
    if (typeof desc === 'function') {
      fn = desc
      desc = null
    }

    // register the completion command.
    completionCommand = cmd || 'completion'
    if (!desc && desc !== false) {
      desc = 'generate bash completion script'
    }
    self.command(completionCommand, desc)

    // a function can be provided
    if (fn) completion.registerFunction(fn)

    return self
  }

  self.showCompletionScript = function ($0) {
    $0 = $0 || self.$0
    _logger.log(completion.generateCompletionScript($0))
    return self
  }

  self.getCompletion = function (args, done) {
    completion.getCompletion(args, done)
  }

  self.locale = function (locale) {
    if (arguments.length === 0) {
      guessLocale()
      return y18n.getLocale()
    }
    detectLocale = false
    y18n.setLocale(locale)
    return self
  }

  self.updateStrings = self.updateLocale = function (obj) {
    detectLocale = false
    y18n.updateLocale(obj)
    return self
  }

  var detectLocale = true
  self.detectLocale = function (detect) {
    detectLocale = detect
    return self
  }
  self.getDetectLocale = function () {
    return detectLocale
  }

  var hasOutput = false
  var exitError = null
  // maybe exit, always capture
  // context about why we wanted to exit.
  self.exit = function (code, err) {
    hasOutput = true
    exitError = err
    if (exitProcess) process.exit(code)
  }

  // we use a custom logger that buffers output,
  // so that we can print to non-CLIs, e.g., chat-bots.
  var _logger = {
    log: function () {
      var args = Array.prototype.slice.call(arguments)
      if (!self._hasParseCallback()) console.log.apply(console, args)
      hasOutput = true
      if (output.length) output += '\n'
      output += args.join(' ')
    },
    error: function () {
      var args = Array.prototype.slice.call(arguments)
      if (!self._hasParseCallback()) console.error.apply(console, args)
      hasOutput = true
      if (output.length) output += '\n'
      output += args.join(' ')
    }
  }
  self._getLoggerInstance = function () {
    return _logger
  }
  // has yargs output an error our help
  // message in the current execution context.
  self._hasOutput = function () {
    return hasOutput
  }

  var recommendCommands
  self.recommendCommands = function () {
    recommendCommands = true
    return self
  }

  self.getUsageInstance = function () {
    return usage
  }

  self.getValidationInstance = function () {
    return validation
  }

  self.getCommandInstance = function () {
    return command
  }

  self.terminalWidth = function () {
    return process.stdout.columns
  }

  Object.defineProperty(self, 'argv', {
    get: function () {
      var args = null

      try {
        args = parseArgs(processArgs)
      } catch (err) {
        usage.fail(err.message, err)
      }

      return args
    },
    enumerable: true
  })

  function parseArgs (args, shortCircuit) {
    options.__ = y18n.__
    options.configuration = pkgUp()['yargs'] || {}
    const parsed = Parser.detailed(args, options)
    var argv = parsed.argv
    if (parseContext) argv = assign(parseContext, argv)
    var aliases = parsed.aliases

    argv.$0 = self.$0
    self.parsed = parsed

    guessLocale() // guess locale lazily, so that it can be turned off in chain.

    // while building up the argv object, there
    // are two passes through the parser. If completion
    // is being performed short-circuit on the first pass.
    if (shortCircuit) {
      return argv
    }

    if (argv._.length) {
      // check for helpOpt in argv._ before running commands
      // assumes helpOpt must be valid if useHelpOptAsCommand is true
      if (useHelpOptAsCommand) {
        // consider any multi-char helpOpt alias as a valid help command
        // unless all helpOpt aliases are single-char
        // note that parsed.aliases is a normalized bidirectional map :)
        var helpCmds = [helpOpt].concat(aliases[helpOpt])
        var multiCharHelpCmds = helpCmds.filter(function (k) {
          return k.length > 1
        })
        if (multiCharHelpCmds.length) helpCmds = multiCharHelpCmds
        // look for and strip any helpCmds from argv._
        argv._ = argv._.filter(function (cmd) {
          if (~helpCmds.indexOf(cmd)) {
            argv[helpOpt] = true
            return false
          }
          return true
        })
      }

      // if there's a handler associated with a
      // command defer processing to it.
      var handlerKeys = command.getCommands()
      if (handlerKeys.length) {
        var firstUnknownCommand
        for (var i = 0, cmd; (cmd = argv._[i]) !== undefined; i++) {
          if (~handlerKeys.indexOf(cmd) && cmd !== completionCommand) {
            setPlaceholderKeys(argv)
            return command.runCommand(cmd, self, parsed)
          } else if (!firstUnknownCommand && cmd !== completionCommand) {
            firstUnknownCommand = cmd
          }
        }

        // recommend a command if recommendCommands() has
        // been enabled, and no commands were found to execute
        if (recommendCommands && firstUnknownCommand) {
          validation.recommendCommands(firstUnknownCommand, handlerKeys)
        }
      }

      // generate a completion script for adding to ~/.bashrc.
      if (completionCommand && ~argv._.indexOf(completionCommand) && !argv[completion.completionKey]) {
        if (exitProcess) setBlocking(true)
        self.showCompletionScript()
        self.exit(0)
      }
    }

    // we must run completions first, a user might
    // want to complete the --help or --version option.
    if (completion.completionKey in argv) {
      if (exitProcess) setBlocking(true)

      // we allow for asynchronous completions,
      // e.g., loading in a list of commands from an API.
      var completionArgs = args.slice(args.indexOf('--' + completion.completionKey) + 1)
      completion.getCompletion(completionArgs, function (completions) {
        ;(completions || []).forEach(function (completion) {
          _logger.log(completion)
        })

        self.exit(0)
      })
      return setPlaceholderKeys(argv)
    }

    var skipValidation = false

    // Handle 'help' and 'version' options
    Object.keys(argv).forEach(function (key) {
      if (key === helpOpt && argv[key]) {
        if (exitProcess) setBlocking(true)

        skipValidation = true
        self.showHelp('log')
        self.exit(0)
      } else if (key === versionOpt && argv[key]) {
        if (exitProcess) setBlocking(true)

        skipValidation = true
        usage.showVersion()
        self.exit(0)
      }
    })

    // Check if any of the options to skip validation were provided
    if (!skipValidation && options.skipValidation.length > 0) {
      skipValidation = Object.keys(argv).some(function (key) {
        return options.skipValidation.indexOf(key) >= 0 && argv[key] === true
      })
    }

    // If the help or version options where used and exitProcess is false,
    // or if explicitly skipped, we won't run validations
    if (!skipValidation) {
      if (parsed.error) throw parsed.error

      // if we're executed via bash completion, don't
      // bother with validation.
      if (!argv[completion.completionKey]) {
        validation.nonOptionCount(argv)
        validation.missingArgumentValue(argv)
        validation.requiredArguments(argv)
        if (strict) validation.unknownArguments(argv, aliases)
        validation.customChecks(argv, aliases)
        validation.limitedChoices(argv)
        validation.implications(argv)
        validation.conflicting(argv)
      }
    }

    return setPlaceholderKeys(argv)
  }

  function guessLocale () {
    if (!detectLocale) return

    try {
      const osLocale = require('os-locale')
      self.locale(osLocale.sync({ spawn: false }))
    } catch (err) {
      // if we explode looking up locale just noop
      // we'll keep using the default language 'en'.
    }
  }

  function setPlaceholderKeys (argv) {
    Object.keys(options.key).forEach(function (key) {
      // don't set placeholder keys for dot
      // notation options 'foo.bar'.
      if (~key.indexOf('.')) return
      if (typeof argv[key] === 'undefined') argv[key] = undefined
    })
    return argv
  }

  return self
}

// rebase an absolute path to a relative one with respect to a base directory
// exported for tests
exports.rebase = rebase
function rebase (base, dir) {
  return path.relative(base, dir)
}