yargs.ts

import { CommandInstance, CommandHandler, CommandBuilderDefinition, CommandBuilder, CommandHandlerCallback, FinishCommandHandler, command as Command, CommandHandlerDefinition } from './command'
import { Dictionary, assertNotStrictEqual, KeyOf, DictionaryKeyof, ValueOf, objectKeys, assertSingleKey } from './common-types'
import {
  Arguments as ParserArguments,
  DetailedArguments as ParserDetailedArguments,
  Configuration as ParserConfiguration,
  Options as ParserOptions,
  ConfigCallback,
  CoerceCallback
} from 'yargs-parser/build/lib/yargs-parser-types'
import { YError } from './yerror'
import { UsageInstance, FailureFunction, usage as Usage } from './usage'
import { argsert } from './argsert'
import * as fs from 'fs'

import { completion as Completion, CompletionInstance, CompletionFunction } from './completion'
import * as path from 'path'

import { validation as Validation, ValidationInstance, KeyOrPos } from './validation'
import { Y18N } from 'y18n'
import { objFilter } from './obj-filter'
import { applyExtends } from './apply-extends'
import { globalMiddlewareFactory, MiddlewareCallback, Middleware } from './middleware'
import * as processArgv from './process-argv'
import { RequireDirectoryOptions } from 'require-directory'
import { isPromise } from './is-promise'
import Parser = require('yargs-parser')
import y18nFactory = require('y18n')
import setBlocking = require('set-blocking')
import findUp = require('find-up')
import requireMainFilename = require('require-main-filename')

export function Yargs (processArgs: string | string[] = [], cwd = process.cwd(), parentRequire = require) {
  const self = {} as YargsInstance
  let command: CommandInstance
  let completion: CompletionInstance | null = null
  let groups: Dictionary<string[]> = {}
  const globalMiddleware: Middleware[] = []
  let output = ''
  const preservedGroups: Dictionary<string[]> = {}
  let usage: UsageInstance
  let validation: ValidationInstance
  let handlerFinishCommand: FinishCommandHandler | null = null

  const y18n = y18nFactory({
    directory: path.resolve(__dirname, '../../locales'),
    updateFiles: false
  })

  self.middleware = globalMiddlewareFactory(globalMiddleware, self)

  self.scriptName = function (scriptName) {
    self.customScriptName = true
    self.$0 = scriptName
    return self
  }

  // ignore the node bin, specify this in your
  // bin file with #!/usr/bin/env node
  let default$0: string[]
  if (/\b(node|iojs|electron)(\.exe)?$/.test(process.argv[0])) {
    default$0 = process.argv.slice(1, 2)
  } else {
    default$0 = process.argv.slice(0, 1)
  }

  self.$0 = default$0
    .map(x => {
      const b = rebase(cwd, x)
      return x.match(/^(\/|([a-zA-Z]:)?\\)/) && b.length < x.length ? b : x
    })
    .join(' ').trim()

  if (process.env._ !== undefined && processArgv.getProcessArgvBin() === 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: [], fullCommands: [], files: [] }
  self.getContext = () => context

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

    // if a key has been explicitly set as local,
    // we should reset it before passing options to command.
    const localLookup: Dictionary<boolean> = {}
    tmpOptions.local.forEach((l) => {
      localLookup[l] = true
      ;(aliases[l] || []).forEach((a) => {
        localLookup[a] = true
      })
    })

    // add all groups not set to local to preserved groups
    Object.assign(
      preservedGroups,
      Object.keys(groups).reduce((acc, groupName) => {
        const keys = groups[groupName].filter(key => !(key in localLookup))
        if (keys.length > 0) {
          acc[groupName] = keys
        }
        return acc
      }, {} as Dictionary<string[]>)
    )
    // groups can now be reset
    groups = {}

    const arrayOptions: KeyOf<Options, string[]>[] = [
      'array', 'boolean', 'string', 'skipValidation',
      'count', 'normalize', 'number',
      'hiddenOptions'
    ]

    const objectOptions: DictionaryKeyof<Options>[] = [
      'narg', 'key', 'alias', 'default', 'defaultDescription',
      'config', 'choices', 'demandedOptions', 'demandedCommands', 'coerce',
      'deprecatedOptions'
    ]

    arrayOptions.forEach(k => {
      tmpOptions[k] = (options[k] || []).filter(k => !localLookup[k])
    })

    objectOptions.forEach(<K extends DictionaryKeyof<Options>>(k: K) => {
      tmpOptions[k] = objFilter(options[k], k => !localLookup[k as string])
    })

    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(localLookup) : Usage(self, y18n)
    validation = validation ? validation.reset(localLookup) : Validation(self, usage, y18n)
    command = command ? command.reset() : Command(self, usage, validation, globalMiddleware)
    if (!completion) completion = Completion(self, usage, command)

    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)
  const frozens: FrozenYargsInstance[] = []
  function freeze () {
    frozens.push({
      options,
      configObjects: options.configObjects.slice(0),
      exitProcess,
      groups,
      strict,
      strictCommands,
      completionCommand,
      output,
      exitError,
      hasOutput,
      parsed: self.parsed,
      parseFn,
      parseContext,
      handlerFinishCommand
    })
    usage.freeze()
    validation.freeze()
    command.freeze()
  }
  function unfreeze () {
    const frozen = frozens.pop()
    assertNotStrictEqual(frozen, undefined)
    let configObjects: Dictionary[]
    ;({
      options,
      configObjects,
      exitProcess,
      groups,
      output,
      exitError,
      hasOutput,
      parsed: self.parsed,
      strict,
      strictCommands,
      completionCommand,
      parseFn,
      parseContext,
      handlerFinishCommand
    } = frozen)
    options.configObjects = configObjects
    usage.unfreeze()
    validation.unfreeze()
    command.unfreeze()
  }

  self.boolean = function (keys) {
    argsert('<array|string>', [keys], arguments.length)
    populateParserHintArray('boolean', keys)
    return self
  }

  self.array = function (keys) {
    argsert('<array|string>', [keys], arguments.length)
    populateParserHintArray('array', keys)
    return self
  }

  self.number = function (keys) {
    argsert('<array|string>', [keys], arguments.length)
    populateParserHintArray('number', keys)
    return self
  }

  self.normalize = function (keys) {
    argsert('<array|string>', [keys], arguments.length)
    populateParserHintArray('normalize', keys)
    return self
  }

  self.count = function (keys) {
    argsert('<array|string>', [keys], arguments.length)
    populateParserHintArray('count', keys)
    return self
  }

  self.string = function (keys) {
    argsert('<array|string>', [keys], arguments.length)
    populateParserHintArray('string', keys)
    return self
  }

  self.requiresArg = function (keys) {
    // the 2nd paramter [number] in the argsert the assertion is mandatory
    // as populateParserHintSingleValueDictionary recursively calls requiresArg
    // with Nan as a 2nd parameter, although we ignore it
    argsert('<array|string|object> [number]', [keys], arguments.length)
    // If someone configures nargs at the same time as requiresArg,
    // nargs should take precedent,
    // see: https://github.com/yargs/yargs/pull/1572
    // TODO: make this work with aliases, using a check similar to
    // checkAllAliases() in yargs-parser.
    if (typeof keys === 'string' && options.narg[keys]) {
      return self
    } else {
      populateParserHintSingleValueDictionary(self.requiresArg, 'narg', keys, NaN)
    }
    return self
  }

  self.skipValidation = function (keys) {
    argsert('<array|string>', [keys], arguments.length)
    populateParserHintArray('skipValidation', keys)
    return self
  }

  function populateParserHintArray<T extends KeyOf<Options, string[]>> (
    type: T,
    keys: string | string[]
  ) {
    keys = ([] as string[]).concat(keys)
    keys.forEach((key) => {
      key = sanitizeKey(key)
      options[type].push(key)
    })
  }

  self.nargs = function (key: string | string[] | Dictionary<number>, value?: number) {
    argsert('<string|object|array> [number]', [key, value], arguments.length)
    populateParserHintSingleValueDictionary(self.nargs, 'narg', key, value)
    return self
  }

  self.choices = function (key: string | string[] | Dictionary<string | string[]>, value?: string | string[]) {
    argsert('<object|string|array> [string|array]', [key, value], arguments.length)
    populateParserHintArrayDictionary(self.choices, 'choices', key, value)
    return self
  }

  self.alias = function (key: string | string[] | Dictionary<string | string[]>, value?: string | string[]) {
    argsert('<object|string|array> [string|array]', [key, value], arguments.length)
    populateParserHintArrayDictionary(self.alias, 'alias', key, value)
    return self
  }

  // TODO: actually deprecate self.defaults.
  self.default = self.defaults = function (
    key: string | string[] | Dictionary<any>,
    value?: any,
    defaultDescription?: string
  ) {
    argsert('<object|string|array> [*] [string]', [key, value, defaultDescription], arguments.length)
    if (defaultDescription) {
      assertSingleKey(key)
      options.defaultDescription[key] = defaultDescription
    }
    if (typeof value === 'function') {
      assertSingleKey(key)
      if (!options.defaultDescription[key]) options.defaultDescription[key] = usage.functionDescription(value)
      value = value.call()
    }
    populateParserHintSingleValueDictionary<'default'>(self.default, 'default', key, value)
    return self
  }

  self.describe = function (key: string | string[] | Dictionary<string>, desc?: string) {
    argsert('<object|string|array> [string]', [key, desc], arguments.length)
    setKey(key, true)
    usage.describe(key, desc)
    return self
  }

  function setKey (key: string | string[] | Dictionary<string | boolean>, set?: boolean | string) {
    populateParserHintSingleValueDictionary(setKey, 'key', key, set)
    return self
  }

  function demandOption (keys: string | string[] | Dictionary<string | undefined>, msg?: string) {
    argsert('<object|string|array> [string]', [keys, msg], arguments.length)
    populateParserHintSingleValueDictionary(self.demandOption, 'demandedOptions', keys, msg)
    return self
  }
  self.demandOption = demandOption

  self.coerce = function (
    keys: string | string[] | Dictionary<CoerceCallback>,
    value?: CoerceCallback
  ) {
    argsert('<object|string|array> [function]', [keys, value], arguments.length)
    populateParserHintSingleValueDictionary(self.coerce, 'coerce', keys, value)
    return self
  }

  function populateParserHintSingleValueDictionary<
    T extends Exclude<DictionaryKeyof<Options>, DictionaryKeyof<Options, any[]>> | 'default',
    K extends keyof Options[T] & string = keyof Options[T] & string,
    V extends ValueOf<Options[T]> = ValueOf<Options[T]>
  > (
    builder: (key: K, value: V, ...otherArgs: any[]) => YargsInstance,
    type: T,
    key: K | K[] | { [key in K]: V },
    value?: V
  ) {
    populateParserHintDictionary<T, K, V>(builder, type, key, value, (type, key, value) => {
      options[type][key] = value as ValueOf<Options[T]>
    })
  }

  function populateParserHintArrayDictionary<
    T extends DictionaryKeyof<Options, any[]>,
    K extends keyof Options[T] & string = keyof Options[T] & string,
    V extends ValueOf<ValueOf<Options[T]>> | ValueOf<ValueOf<Options[T]>>[] = ValueOf<ValueOf<Options[T]>> | ValueOf<ValueOf<Options[T]>>[]
  > (
    builder: (key: K, value: V, ...otherArgs: any[]) => YargsInstance,
    type: T,
    key: K | K[] | { [key in K]: V },
    value?: V
  ) {
    populateParserHintDictionary<T, K, V>(builder, type, key, value, (type, key, value) => {
      options[type][key] = (options[type][key] || [] as Options[T][keyof Options[T]]).concat(value)
    })
  }

  function populateParserHintDictionary<T extends keyof Options, K extends keyof Options[T], V> (
    builder: (key: K, value: V, ...otherArgs: any[]) => YargsInstance,
    type: T,
    key: K | K[] | { [key in K]: V },
    value: V | undefined,
    singleKeyHandler: (type: T, key: K, value?: V) => void
  ) {
    if (Array.isArray(key)) {
      // an array of keys with one value ['x', 'y', 'z'], function parse () {}
      key.forEach((k) => {
        builder(k, value!)
      })
    } else if (((key): key is { [key in K]: V } => typeof key === 'object')(key)) {
      // an object of key value pairs: {'x': parse () {}, 'y': parse() {}}
      for (const k of objectKeys(key)) {
        builder(k, key[k])
      }
    } else {
      singleKeyHandler(type, sanitizeKey(key), value)
    }
  }

  // TODO(bcoe): in future major versions move more objects towards
  // Object.create(null):
  function sanitizeKey<K extends any> (key: K): K;
  function sanitizeKey (key: '__proto__'): '___proto___';
  function sanitizeKey (key: any) {
    if (key === '__proto__') return '___proto___'
    return key
  }

  function deleteFromParserHintObject (optionKey: string) {
    // delete from all parsing hints:
    // boolean, array, key, alias, etc.
    objectKeys(options).forEach((hintKey: keyof Options) => {
      // configObjects is not a parsing hint array
      if (((key): key is 'configObjects' => key === 'configObjects')(hintKey)) return
      const hint = options[hintKey]
      if (Array.isArray(hint)) {
        if (~hint.indexOf(optionKey)) hint.splice(hint.indexOf(optionKey), 1)
      } else if (typeof hint === 'object') {
        delete (hint as Dictionary)[optionKey]
      }
    })
    // now delete the description from usage.js.
    delete usage.getDescriptions()[optionKey]
  }

  self.config = function config (
    key: string | string[] | Dictionary = 'config',
    msg?: string | ConfigCallback,
    parseFn?: ConfigCallback
  ) {
    argsert('[object|string] [string|function] [function]', [key, msg, parseFn], arguments.length)
    // allow a config object to be provided directly.
    if ((typeof key === 'object') && !Array.isArray(key)) {
      key = applyExtends(key, cwd, self.getParserConfiguration()['deep-merge-config'])
      options.configObjects = (options.configObjects || []).concat(key)
      return self
    }

    // allow for a custom parsing function.
    if (typeof msg === 'function') {
      parseFn = msg
      msg = undefined
    }

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

    return self
  }

  self.example = function (cmd: string | [string, string?][], description?: string) {
    argsert('<string|array> [string]', [cmd, description], arguments.length)

    if (Array.isArray(cmd)) {
      cmd.forEach((exampleParams) => self.example(...exampleParams))
    } else {
      usage.example(cmd, description)
    }

    return self
  }

  self.command = function (
    cmd: string | string[] | CommandHandlerDefinition,
    description?: CommandHandler['description'],
    builder?: CommandBuilderDefinition | CommandBuilder,
    handler?: CommandHandlerCallback,
    middlewares?: Middleware[],
    deprecated?: boolean
  ) {
    argsert('<string|array|object> [string|boolean] [function|object] [function] [array] [boolean|string]', [cmd, description, builder, handler, middlewares, deprecated], arguments.length)
    command.addHandler(cmd, description, builder, handler, middlewares, deprecated)
    return self
  }

  self.commandDir = function (dir, opts) {
    argsert('<string> [object]', [dir, opts], arguments.length)
    const req = parentRequire || require
    command.addDirectory(dir, self.getContext(), req, require('get-caller-file')(), opts)
    return self
  }

  // TODO: deprecate self.demand in favor of
  // .demandCommand() .demandOption().
  self.demand = self.required = self.require = function demand (
    keys: string | string[] | Dictionary<string | undefined> | number,
    max?: number | string[] | string | true,
    msg?: string | true
  ) {
    // you can optionally provide a 'max' key,
    // which will raise an exception if too many '_'
    // options are provided.
    if (Array.isArray(max)) {
      max.forEach((key) => {
        assertNotStrictEqual(msg, true as true)
        demandOption(key, msg)
      })
      max = Infinity
    } else if (typeof max !== 'number') {
      msg = max
      max = Infinity
    }

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

    return self
  }

  self.demandCommand = function demandCommand (
    min: number = 1,
    max?: number | string,
    minMsg?: string | null,
    maxMsg?: string | null
  ) {
    argsert('[number] [number|string] [string|null|undefined] [string|null|undefined]', [min, max, minMsg, maxMsg], arguments.length)

    if (typeof max !== 'number') {
      minMsg = max
      max = Infinity
    }

    self.global('_', false)

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

    return self
  }

  self.getDemandedOptions = () => {
    argsert([], 0)
    return options.demandedOptions
  }

  self.getDemandedCommands = () => {
    argsert([], 0)
    return options.demandedCommands
  }

  self.deprecateOption = function deprecateOption (option, message) {
    argsert('<string> [string|boolean]', [option, message], arguments.length)
    options.deprecatedOptions[option] = message
    return self
  }

  self.getDeprecatedOptions = () => {
    argsert([], 0)
    return options.deprecatedOptions
  }

  self.implies = function (
    key: string | Dictionary<KeyOrPos | KeyOrPos[]>,
    value?: KeyOrPos | KeyOrPos[]
  ) {
    argsert('<string|object> [number|string|array]', [key, value], arguments.length)
    validation.implies(key, value)
    return self
  }

  self.conflicts = function (key1: string | Dictionary<string | string[]>, key2?: string | string[]) {
    argsert('<string|object> [string|array]', [key1, key2], arguments.length)
    validation.conflicts(key1, key2)
    return self
  }

  self.usage = function (
    msg: string | null,
    description?: CommandHandler['description'],
    builder?: CommandBuilderDefinition | CommandBuilder,
    handler?: CommandHandlerCallback
  ) {
    argsert('<string|null|undefined> [string|boolean] [function|object] [function]', [msg, description, builder, handler], arguments.length)

    if (description !== undefined) {
      assertNotStrictEqual(msg, null)
      // .usage() can be used as an alias for defining
      // a default command.
      if ((msg || '').match(/^\$0( |$)/)) {
        return self.command(msg, description, builder, handler)
      } else {
        throw new YError('.usage() description must start with $0 if being used as alias for .command()')
      }
    } else {
      usage.usage(msg)
      return self
    }
  }

  self.epilogue = self.epilog = function (msg) {
    argsert('<string>', [msg], arguments.length)
    usage.epilog(msg)
    return self
  }

  self.fail = function (f) {
    argsert('<function>', [f], arguments.length)
    usage.failFn(f)
    return self
  }

  self.onFinishCommand = function (f) {
    argsert('<function>', [f], arguments.length)
    handlerFinishCommand = f
    return self
  }

  self.getHandlerFinishCommand = () => handlerFinishCommand

  self.check = function (f, _global) {
    argsert('<function> [boolean]', [f, _global], arguments.length)
    validation.check(f, _global !== false)
    return self
  }

  self.global = function global (globals, global) {
    argsert('<string|array> [boolean]', [globals, global], arguments.length)
    globals = ([] as string[]).concat(globals)
    if (global !== false) {
      options.local = options.local.filter(l => globals.indexOf(l) === -1)
    } else {
      globals.forEach((g) => {
        if (options.local.indexOf(g) === -1) options.local.push(g)
      })
    }
    return self
  }

  self.pkgConf = function pkgConf (key, rootPath) {
    argsert('<string> [string]', [key, rootPath], arguments.length)
    let conf = null
    // prefer cwd to require-main-filename in this method
    // since we're looking for e.g. "nyc" config in nyc consumer
    // rather than "yargs" config in nyc (where nyc is the main filename)
    const obj = pkgUp(rootPath || cwd)

    // If an object exists in the key, add it to options.configObjects
    if (obj[key] && typeof obj[key] === 'object') {
      conf = applyExtends(obj[key], rootPath || cwd, self.getParserConfiguration()['deep-merge-config'])
      options.configObjects = (options.configObjects || []).concat(conf)
    }

    return self
  }

  const pkgs: Dictionary = {}
  function pkgUp (rootPath?: string) {
    const npath = rootPath || '*'
    if (pkgs[npath]) return pkgs[npath]

    let obj = {}
    try {
      let startDir = rootPath || requireMainFilename(parentRequire)

      // When called in an environment that lacks require.main.filename, such as a jest test runner,
      // startDir is already process.cwd(), and should not be shortened.
      // Whether or not it is _actually_ a directory (e.g., extensionless bin) is irrelevant, find-up handles it.
      if (!rootPath && path.extname(startDir)) {
        startDir = path.dirname(startDir)
      }

      const pkgJsonPath = findUp.sync('package.json', {
        cwd: startDir
      })
      assertNotStrictEqual(pkgJsonPath, undefined)
      obj = JSON.parse(fs.readFileSync(pkgJsonPath).toString())
    } catch (noop) {}

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

  let parseFn: ParseCallback | null = null
  let parseContext: object | null = null
  self.parse = function parse (
    args?: string | string[],
    shortCircuit?: object | ParseCallback | boolean,
    _parseFn?: ParseCallback
  ) {
    argsert('[string|array] [function|boolean|object] [function]', [args, shortCircuit, _parseFn], arguments.length)
    freeze()
    if (typeof args === 'undefined') {
      const argv = self._parseArgs(processArgs)
      const tmpParsed = self.parsed
      unfreeze()
      // TODO: remove this compatibility hack when we release yargs@15.x:
      self.parsed = tmpParsed
      return argv
    }

    // 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 as ParseCallback
      shortCircuit = false
    }
    // completion short-circuits the parsing process,
    // skipping validation, etc.
    if (!shortCircuit) processArgs = args

    if (parseFn) exitProcess = false

    const parsed = self._parseArgs(args, !!shortCircuit)
    completion!.setParsed(self.parsed as DetailedArguments)
    if (parseFn) parseFn(exitError, parsed, output)
    unfreeze()

    return parsed
  }

  self._getParseContext = () => parseContext || {}

  self._hasParseCallback = () => !!parseFn

  self.option = self.options = function option (
    key: string | Dictionary<OptionDefinition>,
    opt?: OptionDefinition
  ) {
    argsert('<string|object> [object]', [key, opt], arguments.length)
    if (typeof key === 'object') {
      Object.keys(key).forEach((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)

      const deprecate = opt.deprecate || opt.deprecated

      if (deprecate) {
        self.deprecateOption(key, deprecate)
      }

      const demand = opt.demand || opt.required || opt.require

      // A required option can be specified via "demand: true".
      if (demand) {
        self.demand(key, demand)
      }

      if (opt.demandOption) {
        self.demandOption(key, typeof opt.demandOption === 'string' ? opt.demandOption : undefined)
      }

      if (opt.conflicts) {
        self.conflicts(key, opt.conflicts)
      }

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

      if (opt.implies !== undefined) {
        self.implies(key, opt.implies)
      }

      if (opt.nargs !== undefined) {
        self.nargs(key, opt.nargs)
      }

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

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

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

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

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

      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 (typeof opt.global === 'boolean') {
        self.global(key, opt.global)
      }

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

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

      const desc = opt.describe || opt.description || opt.desc
      self.describe(key, desc)
      if (opt.hidden) {
        self.hide(key)
      }

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

    return self
  }
  self.getOptions = () => options

  self.positional = function (key, opts) {
    argsert('<string> <object>', [key, opts], arguments.length)
    if (context.resets === 0) {
      throw new YError(".positional() can only be called in a command's builder function")
    }

    // .positional() only supports a subset of the configuration
    // options available to .option().
    const supportedOpts: (keyof PositionalDefinition)[] = ['default', 'defaultDescription', 'implies', 'normalize',
      'choices', 'conflicts', 'coerce', 'type', 'describe',
      'desc', 'description', 'alias']
    opts = objFilter(opts, (k, v) => {
      let accept = supportedOpts.indexOf(k) !== -1
      // type can be one of string|number|boolean.
      if (k === 'type' && ['string', 'number', 'boolean'].indexOf(v) === -1) accept = false
      return accept
    })

    // copy over any settings that can be inferred from the command string.
    const fullCommand = context.fullCommands[context.fullCommands.length - 1]
    const parseOptions = fullCommand ? command.cmdToParseOptions(fullCommand) : {
      array: [],
      alias: {},
      default: {},
      demand: {}
    }
    objectKeys(parseOptions).forEach((pk) => {
      const parseOption = parseOptions[pk]
      if (Array.isArray(parseOption)) {
        if (parseOption.indexOf(key) !== -1) opts[pk] = true
      } else {
        if (parseOption[key] && !(pk in opts)) opts[pk] = parseOption[key]
      }
    })
    self.group(key, usage.getPositionalGroupName())
    return self.option(key, opts)
  }

  self.group = function group (opts, groupName) {
    argsert('<string|array> <string>', [opts, groupName], arguments.length)
    const existing = preservedGroups[groupName] || groups[groupName]
    if (preservedGroups[groupName]) {
      // we now only need to track this group name in groups.
      delete preservedGroups[groupName]
    }

    const seen: Dictionary<boolean> = {}
    groups[groupName] = (existing || []).concat(opts).filter((key) => {
      if (seen[key]) return false
      return (seen[key] = true)
    })
    return self
  }
  // combine explicit and preserved groups. explicit groups should be first
  self.getGroups = () => Object.assign({}, groups, preservedGroups)

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

  self.wrap = function (cols) {
    argsert('<number|null|undefined>', [cols], arguments.length)
    usage.wrap(cols)
    return self
  }

  let strict = false
  self.strict = function (enabled) {
    argsert('[boolean]', [enabled], arguments.length)
    strict = enabled !== false
    return self
  }
  self.getStrict = () => strict

  let strictCommands = false
  self.strictCommands = function (enabled) {
    argsert('[boolean]', [enabled], arguments.length)
    strictCommands = enabled !== false
    return self
  }
  self.getStrictCommands = () => strictCommands

  let parserConfig: Configuration = {}
  self.parserConfiguration = function parserConfiguration (config) {
    argsert('<object>', [config], arguments.length)
    parserConfig = config
    return self
  }
  self.getParserConfiguration = () => parserConfig

  self.showHelp = function (level) {
    argsert('[string|function]', [level], arguments.length)
    if (!self.parsed) self._parseArgs(processArgs) // run parser, if it has not already been executed.
    if (command.hasDefaultCommand()) {
      context.resets++ // override the restriction on top-level positoinals.
      command.runDefaultBuilderOn(self)
    }
    usage.showHelp(level)
    return self
  }

  let versionOpt: string | null = null
  self.version = function version (opt?: string | false, msg?: string, ver?: string) {
    const defaultVersionOpt = 'version'
    argsert('[boolean|string] [string] [string]', [opt, msg, ver], arguments.length)

    // nuke the key previously configured
    // to return version #.
    if (versionOpt) {
      deleteFromParserHintObject(versionOpt)
      usage.version(undefined)
      versionOpt = null
    }

    if (arguments.length === 0) {
      ver = guessVersion()
      opt = defaultVersionOpt
    } else if (arguments.length === 1) {
      if (opt === false) { // disable default 'version' key.
        return self
      }
      ver = opt
      opt = defaultVersionOpt
    } else if (arguments.length === 2) {
      ver = msg
      msg = undefined
    }

    versionOpt = typeof opt === 'string' ? opt : defaultVersionOpt
    msg = msg || usage.deferY18nLookup('Show version number')

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

  function guessVersion () {
    const obj = pkgUp()

    return obj.version || 'unknown'
  }

  let helpOpt: string | null = null
  self.addHelpOpt = self.help = function addHelpOpt (opt?: string | false, msg?: string) {
    const defaultHelpOpt = 'help'
    argsert('[string|boolean] [string]', [opt, msg], arguments.length)

    // nuke the key previously configured
    // to return help.
    if (helpOpt) {
      deleteFromParserHintObject(helpOpt)
      helpOpt = null
    }

    if (arguments.length === 1) {
      if (opt === false) return self
    }

    // use arguments, fallback to defaults for opt and msg
    helpOpt = typeof opt === 'string' ? opt : defaultHelpOpt
    self.boolean(helpOpt)
    self.describe(helpOpt, msg || usage.deferY18nLookup('Show help'))
    return self
  }

  const defaultShowHiddenOpt = 'show-hidden'
  options!.showHiddenOpt = defaultShowHiddenOpt
  self.addShowHiddenOpt = self.showHidden = function addShowHiddenOpt (opt?: string | false, msg?: string) {
    argsert('[string|boolean] [string]', [opt, msg], arguments.length)

    if (arguments.length === 1) {
      if (opt === false) return self
    }

    const showHiddenOpt = typeof opt === 'string' ? opt : defaultShowHiddenOpt
    self.boolean(showHiddenOpt)
    self.describe(showHiddenOpt, msg || usage.deferY18nLookup('Show hidden options'))
    options.showHiddenOpt = showHiddenOpt
    return self
  }

  self.hide = function hide (key) {
    argsert('<string>', [key], arguments.length)
    options.hiddenOptions.push(key)
    return self
  }

  self.showHelpOnFail = function showHelpOnFail (enabled?: string | boolean, message?: string) {
    argsert('[boolean|string] [string]', [enabled, message], arguments.length)
    usage.showHelpOnFail(enabled, message)
    return self
  }

  var exitProcess = true
  self.exitProcess = function (enabled = true) {
    argsert('[boolean]', [enabled], arguments.length)
    exitProcess = enabled
    return self
  }
  self.getExitProcess = () => exitProcess

  var completionCommand: string | null = null
  self.completion = function (cmd?: string, desc?: string | false | CompletionFunction, fn?: CompletionFunction) {
    argsert('[string] [string|boolean|function] [function]', [cmd, desc, fn], arguments.length)

    // 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 = undefined
    }

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

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

    return self
  }

  self.showCompletionScript = function ($0, cmd) {
    argsert('[string] [string]', [$0, cmd], arguments.length)
    $0 = $0 || self.$0
    _logger.log(completion!.generateCompletionScript($0, cmd || completionCommand || 'completion'))
    return self
  }

  self.getCompletion = function (args, done) {
    argsert('<array> <function>', [args, done], arguments.length)
    completion!.getCompletion(args, done)
  }

  self.locale = function (locale?: string): any {
    argsert('[string]', [locale], arguments.length)
    if (!locale) {
      guessLocale()
      return y18n.getLocale()
    }
    detectLocale = false
    y18n.setLocale(locale)
    return self
  }

  self.updateStrings = self.updateLocale = function (obj) {
    argsert('<object>', [obj], arguments.length)
    detectLocale = false
    y18n.updateLocale(obj)
    return self
  }

  let detectLocale = true
  self.detectLocale = function (detect) {
    argsert('<boolean>', [detect], arguments.length)
    detectLocale = detect
    return self
  }
  self.getDetectLocale = () => detectLocale

  var hasOutput = false
  var exitError: YError | string | undefined | null = null
  // maybe exit, always capture
  // context about why we wanted to exit.
  self.exit = (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.
  const _logger = {
    log (...args: any[]) {
      if (!self._hasParseCallback()) console.log(...args)
      hasOutput = true
      if (output.length) output += '\n'
      output += args.join(' ')
    },
    error (...args: any[]) {
      if (!self._hasParseCallback()) console.error(...args)
      hasOutput = true
      if (output.length) output += '\n'
      output += args.join(' ')
    }
  }
  self._getLoggerInstance = () => _logger
  // has yargs output an error our help
  // message in the current execution context.
  self._hasOutput = () => hasOutput

  self._setHasOutput = () => {
    hasOutput = true
  }

  let recommendCommands: boolean
  self.recommendCommands = function (recommend = true) {
    argsert('[boolean]', [recommend], arguments.length)
    recommendCommands = recommend
    return self
  }

  self.getUsageInstance = () => usage

  self.getValidationInstance = () => validation

  self.getCommandInstance = () => command

  self.terminalWidth = () => {
    argsert([], 0)
    return typeof process.stdout.columns !== 'undefined' ? process.stdout.columns : null
  }

  Object.defineProperty(self, 'argv', {
    get: () => self._parseArgs(processArgs),
    enumerable: true
  })

  self._parseArgs = function parseArgs (
    args: string | string [] | null,
    shortCircuit?: boolean | null,
    _calledFromCommand?: boolean,
    commandIndex?: number
  ) {
    let skipValidation = !!_calledFromCommand
    args = args || processArgs

    options.__ = y18n.__
    options.configuration = self.getParserConfiguration()

    const populateDoubleDash = !!options.configuration['populate--']
    const config = Object.assign({}, options.configuration, {
      'populate--': true
    })
    const parsed = Parser.detailed(args, Object.assign({}, options, {
      configuration: config
    })) as DetailedArguments

    let argv = parsed.argv as Arguments
    if (parseContext) argv = Object.assign({}, argv, parseContext)
    const aliases = parsed.aliases

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

    try {
      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 (populateDoubleDash || _calledFromCommand) ? argv : self._copyDoubleDash(argv)
      }

      // if there's a handler associated with a
      // command defer processing to it.
      if (helpOpt) {
        // 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 :)
        const helpCmds = [helpOpt]
          .concat(aliases[helpOpt] || [])
          .filter(k => k.length > 1)
        // check if help should trigger and strip it from _.
        if (~helpCmds.indexOf('' + argv._[argv._.length - 1])) {
          argv._.pop()
          argv[helpOpt] = true
        }
      }

      const handlerKeys = command.getCommands()
      const requestCompletions = completion!.completionKey in argv
      const skipRecommendation = argv[helpOpt!] || requestCompletions
      const skipDefaultCommand = skipRecommendation && (handlerKeys.length > 1 || handlerKeys[0] !== '$0')

      if (argv._.length) {
        if (handlerKeys.length) {
          let firstUnknownCommand
          for (let i = (commandIndex || 0), cmd; argv._[i] !== undefined; i++) {
            cmd = String(argv._[i])
            if (~handlerKeys.indexOf(cmd) && cmd !== completionCommand) {
              // commands are executed using a recursive algorithm that executes
              // the deepest command first; we keep track of the position in the
              // argv._ array that is currently being executed.
              const innerArgv = command.runCommand(cmd, self, parsed, i + 1)
              return populateDoubleDash ? innerArgv : self._copyDoubleDash(innerArgv)
            } else if (!firstUnknownCommand && cmd !== completionCommand) {
              firstUnknownCommand = cmd
              break
            }
          }

          // run the default command, if defined
          if (command.hasDefaultCommand() && !skipDefaultCommand) {
            const innerArgv = command.runCommand(null, self, parsed)
            return populateDoubleDash ? innerArgv : self._copyDoubleDash(innerArgv)
          }

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

        // generate a completion script for adding to ~/.bashrc.
        if (completionCommand && ~argv._.indexOf(completionCommand) && !requestCompletions) {
          if (exitProcess) setBlocking(true)
          self.showCompletionScript()
          self.exit(0)
        }
      } else if (command.hasDefaultCommand() && !skipDefaultCommand) {
        const innerArgv = command.runCommand(null, self, parsed)
        return populateDoubleDash ? innerArgv : self._copyDoubleDash(innerArgv)
      }

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

        // we allow for asynchronous completions,
        // e.g., loading in a list of commands from an API.
        args = ([] as string[]).concat(args)
        const completionArgs = args.slice(args.indexOf(`--${completion!.completionKey}`) + 1)
        completion!.getCompletion(completionArgs, (completions) => {
          ;(completions || []).forEach((completion) => {
            _logger.log(completion)
          })

          self.exit(0)
        })
        return (populateDoubleDash || _calledFromCommand) ? argv : self._copyDoubleDash(argv)
      }

      // Handle 'help' and 'version' options
      // if we haven't already output help!
      if (!hasOutput) {
        Object.keys(argv).forEach((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(key => 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 new YError(parsed.error.message)

        // if we're executed via bash completion, don't
        // bother with validation.
        if (!requestCompletions) {
          self._runValidation(argv, aliases, {}, parsed.error)
        }
      }
    } catch (err) {
      if (err instanceof YError) usage.fail(err.message, err)
      else throw err
    }

    return (populateDoubleDash || _calledFromCommand) ? argv : self._copyDoubleDash(argv)
  }

  // to simplify the parsing of positionals in commands,
  // we temporarily populate '--' rather than _, with arguments
  // after the '--' directive. After the parse, we copy these back.
  self._copyDoubleDash = function (argv: Arguments | Promise<Arguments>): any {
    if (isPromise(argv) || !argv._ || !argv['--']) return argv
    argv._.push.apply(argv._, argv['--'])

    // TODO(bcoe): refactor command parsing such that this delete is not
    // necessary: https://github.com/yargs/yargs/issues/1482
    try {
      delete argv['--']
    } catch (_err) {}

    return argv
  }

  self._runValidation = function runValidation (argv, aliases, positionalMap, parseErrors, isDefaultCommand = false) {
    if (parseErrors) throw new YError(parseErrors.message)
    validation.nonOptionCount(argv)
    validation.requiredArguments(argv)
    let failedStrictCommands = false
    if (strictCommands) {
      failedStrictCommands = validation.unknownCommands(argv)
    }
    if (strict && !failedStrictCommands) {
      validation.unknownArguments(argv, aliases, positionalMap, isDefaultCommand)
    }
    validation.customChecks(argv, aliases)
    validation.limitedChoices(argv)
    validation.implications(argv)
    validation.conflicting(argv)
  }

  function guessLocale () {
    if (!detectLocale) return
    const locale = process.env.LC_ALL || process.env.LC_MESSAGES || process.env.LANG || process.env.LANGUAGE || 'en_US'
    self.locale(locale.replace(/[.:].*/, ''))
  }

  // an app should almost always have --version and --help,
  // if you *really* want to disable this use .help(false)/.version(false).
  self.help()
  self.version()

  return self
}

// rebase an absolute path to a relative one with respect to a base directory
// exported for tests
export interface RebaseFunction {
  (base: string, dir: string): string
}

export const rebase: RebaseFunction = (base, dir) => path.relative(base, dir)

/** Instance of the yargs module. */
export interface YargsInstance {
  $0: string
  argv: Arguments
  customScriptName: boolean
  parsed: DetailedArguments | false
  _copyDoubleDash<T extends Arguments | Promise<Arguments>> (argv: T): T
  _getLoggerInstance (): LoggerInstance
  _getParseContext(): Object
  _hasOutput (): boolean
  _hasParseCallback (): boolean
  _parseArgs: {
    (args: null, shortCircuit: null, _calledFromCommand: boolean, commandIndex?: number): Arguments | Promise<Arguments>
    (args: string | string[], shortCircuit?: boolean): Arguments | Promise<Arguments>
  }
  _runValidation (
    argv: Arguments,
    aliases: Dictionary<string[]>,
    positionalMap: Dictionary<string[]>,
    parseErrors: Error | null,
    isDefaultCommand?: boolean
  ): void
  _setHasOutput (): void
  addHelpOpt: {
    (opt?: string | false): YargsInstance
    (opt?: string, msg?: string): YargsInstance
  }
  addShowHiddenOpt: {
    (opt?: string | false): YargsInstance
    (opt?: string, msg?: string): YargsInstance
  }
  alias: {
    (keys: string | string[], aliases: string | string[]): YargsInstance
    (keyAliases: Dictionary<string | string[]>): YargsInstance
  }
  array (keys: string | string[]): YargsInstance
  boolean (keys: string | string[]): YargsInstance
  check(f: (argv: Arguments, aliases: Dictionary<string[]>) => any, _global?: boolean): YargsInstance
  choices: {
    (keys: string | string[], choices: string | string[]): YargsInstance
    (keyChoices: Dictionary<string | string[]>): YargsInstance
  }
  coerce: {
    (keys: string | string[], coerceCallback: CoerceCallback): YargsInstance
    (keyCoerceCallbacks: Dictionary<CoerceCallback>): YargsInstance
  }
  command (handler: CommandHandlerDefinition): YargsInstance
  command (
    cmd: string | string[],
    description: CommandHandler['description'],
    builder ?: CommandBuilderDefinition | CommandBuilder,
    handler ?: CommandHandlerCallback,
    commandMiddleware ?: Middleware[],
    deprecated ?: boolean
  ): YargsInstance
  commandDir (dir: string, opts?: RequireDirectoryOptions<any>): YargsInstance
  completion: {
    (cmd?: string, fn?: CompletionFunction): YargsInstance
    (cmd?: string, desc?: string | false, fn?: CompletionFunction): YargsInstance
  }
  config: {
    (config: Dictionary): YargsInstance
    (keys?: string | string[], configCallback?: ConfigCallback): YargsInstance
    (keys?: string | string[], msg?: string, configCallback?: ConfigCallback): YargsInstance
  }
  conflicts: {
    (key: string, conflictsWith: string | string[]): YargsInstance
    (keyConflicts: Dictionary<string | string[]>): YargsInstance
  }
  count (keys: string | string[]): YargsInstance
  default: {
    (key: string, value: any, defaultDescription?: string): YargsInstance
    (keys: string[], value: Exclude<any, Function>): YargsInstance
    (keys: Dictionary<any>): YargsInstance
  }
  defaults: YargsInstance['default']
  demand: {
    (min: number, max?: number | string, msg?: string): YargsInstance
    (keys: string | string[], msg?: string | true): YargsInstance
    (keys: string | string[], max: string[], msg?: string | true): YargsInstance
    (keyMsgs: Dictionary<string | undefined>): YargsInstance
    (keyMsgs: Dictionary<string | undefined>, max: string[], msg?: string): YargsInstance
  }
  demandCommand (): YargsInstance
  demandCommand (min: number, minMsg?: string): YargsInstance
  demandCommand (min: number, max: number, minMsg?: string | null, maxMsg?: string | null): YargsInstance
  demandOption: {
    (keys: string | string[], msg?: string): YargsInstance
    (keyMsgs: Dictionary<string | undefined>): YargsInstance
  }
  deprecateOption (option: string, message?: string | boolean): YargsInstance
  describe: {
    (keys: string | string[], description?: string): YargsInstance
    (keyDescriptions: Dictionary<string>): YargsInstance
  }
  detectLocale (detect: boolean): YargsInstance
  env (prefix?: string | false): YargsInstance
  epilog: YargsInstance['epilogue']
  epilogue (msg: string): YargsInstance
  example (cmd: string | [string, string?][], description?: string): YargsInstance
  exit (code: number, err?: YError | string): void
  exitProcess (enabled: boolean): YargsInstance
  fail (f: FailureFunction): YargsInstance
  getCommandInstance (): CommandInstance
  getCompletion(args: string[], done: (completions: string[]) => any): void
  getContext (): Context
  getDemandedCommands (): Options['demandedCommands']
  getDemandedOptions (): Options['demandedOptions']
  getDeprecatedOptions (): Options['deprecatedOptions']
  getDetectLocale(): boolean
  getExitProcess (): boolean
  getGroups (): Dictionary<string[]>
  getHandlerFinishCommand (): FinishCommandHandler | null
  getOptions (): Options
  getParserConfiguration (): Configuration
  getStrict (): boolean
  getStrictCommands (): boolean
  getUsageInstance (): UsageInstance
  getValidationInstance (): ValidationInstance
  global (keys: string | string[], global?: boolean): YargsInstance
  group (keys: string| string[], groupName: string): YargsInstance
  help: YargsInstance['addHelpOpt']
  hide (key: string): YargsInstance
  implies: {
    (key: string, implication: KeyOrPos | KeyOrPos[]): YargsInstance
    (keyImplications: Dictionary<KeyOrPos | KeyOrPos[]>): YargsInstance
  }
  locale: {
    (): string
    (locale: string): YargsInstance
  }
  middleware (callback: MiddlewareCallback | MiddlewareCallback[], applyBeforeValidation?: boolean): YargsInstance
  nargs: {
    (keys: string | string[], nargs: number): YargsInstance
    (keyNargs: Dictionary<number>): YargsInstance
  }
  normalize (keys: string | string[]): YargsInstance
  number (keys: string | string[]): YargsInstance
  onFinishCommand (f: FinishCommandHandler): YargsInstance
  option: {
    (key: string, optionDefinition: OptionDefinition): YargsInstance
    (keyOptionDefinitions: Dictionary<OptionDefinition>): YargsInstance
  }
  options: YargsInstance['option']
  parse: {
    (): Arguments | Promise<Arguments>
    (args: string | string[], context: object, parseCallback?: ParseCallback): Arguments | Promise<Arguments>
    (args: string | string[], parseCallback: ParseCallback): Arguments | Promise<Arguments>
    (args: string | string[], shortCircuit: boolean): Arguments | Promise<Arguments>
  }
  parserConfiguration (config: Configuration): YargsInstance
  pkgConf (key: string, rootPath?: string): YargsInstance
  positional (key: string, positionalDefinition: PositionalDefinition): YargsInstance
  recommendCommands (recommend: boolean): YargsInstance
  require: YargsInstance['demand']
  required: YargsInstance['demand']
  requiresArg (keys: string | string[] | Dictionary): YargsInstance
  reset (aliases?: DetailedArguments['aliases']): YargsInstance
  resetOptions (aliases?: DetailedArguments['aliases']): YargsInstance
  scriptName (scriptName: string): YargsInstance
  showCompletionScript($0?: string, cmd?: string): YargsInstance
  showHelp (level: 'error' | 'log' | ((message: string) => void)): YargsInstance
  showHelpOnFail: {
    (message?: string): YargsInstance
    (enabled: boolean, message: string): YargsInstance
  }
  showHidden: YargsInstance['addShowHiddenOpt']
  skipValidation (keys: string | string[]): YargsInstance
  strict (enable?: boolean): YargsInstance
  strictCommands (enable?: boolean): YargsInstance
  string (key: string | string []): YargsInstance
  terminalWidth (): number | null
  updateStrings (obj: Dictionary<string>): YargsInstance
  updateLocale: YargsInstance['updateStrings']
  usage: {
    (msg: string | null): YargsInstance
    (
      msg: string,
      description: CommandHandler['description'],
      builder?: CommandBuilderDefinition | CommandBuilder,
      handler?: CommandHandlerCallback
    ): YargsInstance
  }
  version: {
    (ver?: string | false): YargsInstance
    (key?: string, ver?: string): YargsInstance
    (key?: string, msg?: string, ver?: string): YargsInstance
  }
  wrap (cols: number | null | undefined): YargsInstance
}

export function isYargsInstance (y: YargsInstance | void): y is YargsInstance {
  return !!y && (typeof y._parseArgs === 'function')
}

/** Yargs' context. */
export interface Context {
  commands: string[]
  files: string[]
  fullCommands: string[]
}

type LoggerInstance = Pick<Console, 'error' | 'log'>

export interface Options extends ParserOptions {
  __: Y18N['__']
  alias: Dictionary<string[]>
  array: string[]
  boolean: string[]
  choices: Dictionary<string[]>
  config: Dictionary<ConfigCallback | boolean>
  configObjects: Dictionary[]
  configuration: Configuration
  count: string[]
  defaultDescription: Dictionary<string | undefined>
  demandedCommands: Dictionary<{
    min: number,
    max: number,
    minMsg?: string | null,
    maxMsg?: string | null
  }>
  demandedOptions: Dictionary<string | undefined>
  deprecatedOptions: Dictionary<string | boolean | undefined>
  hiddenOptions: string[]
  /** Manually set keys */
  key: Dictionary<boolean | string>
  local: string[]
  normalize: string[]
  number: string[]
  showHiddenOpt: string
  skipValidation: string[]
  string: string[]
}

export interface Configuration extends Partial<ParserConfiguration> {
  /** Should a config object be deep-merged with the object config it extends? */
  'deep-merge-config'?: boolean
  /** Should commands be sorted in help? */
  'sort-commands'?: boolean
}

export interface OptionDefinition {
  alias?: string | string[]
  array?: boolean
  boolean?: boolean
  choices?: string | string[]
  coerce?: CoerceCallback
  config?: boolean
  configParser?: ConfigCallback
  conflicts?: string | string[]
  count?: boolean
  default?: any
  defaultDescription?: string
  deprecate?: string | boolean
  deprecated?: OptionDefinition['deprecate']
  desc?: string
  describe?: OptionDefinition['desc']
  description?: OptionDefinition['desc']
  demand?: string | true
  demandOption?: OptionDefinition['demand']
  global?: boolean
  group?: string
  hidden?: boolean
  implies?: string | number | KeyOrPos[]
  nargs?: number
  normalize?: boolean
  number?: boolean
  require?: OptionDefinition['demand']
  required?: OptionDefinition['demand']
  requiresArg?: boolean
  skipValidation?: boolean
  string?: boolean
  type?: 'array' | 'boolean' | 'count' | 'number' | 'string'
}

interface PositionalDefinition extends Pick<OptionDefinition,
  'alias' |
  'array' |
  'coerce' |
  'choices' |
  'conflicts' |
  'default' |
  'defaultDescription' |
  'demand' |
  'desc' |
  'describe' |
  'description' |
  'implies' |
  'normalize'
> {
  type?: 'boolean' | 'number' | 'string'
}

interface FrozenYargsInstance {
  options: Options
  configObjects: Dictionary[]
  exitProcess: boolean
  groups: Dictionary<string[]>
  strict: boolean
  strictCommands: boolean
  completionCommand: string | null
  output: string
  exitError: YError | string | undefined | null
  hasOutput: boolean
  parsed: DetailedArguments | false
  parseFn: ParseCallback | null
  parseContext: object | null
  handlerFinishCommand: FinishCommandHandler | null
}

interface ParseCallback {
  (err: YError | string | undefined | null, argv: Arguments | Promise<Arguments>, output: string): void
}

export interface Arguments extends ParserArguments {
  /** The script name or node command */
  $0: string
}

export interface DetailedArguments extends ParserDetailedArguments {
  argv: Arguments
}