eltro/lib/watch/has-native-recursive.mjs

import fs from 'fs'
import os from 'os'
import path from 'path'
import * as is from './is.mjs'

let IS_SUPPORT
let TEMP_DIR = os.tmpdir && os.tmpdir()
  || process.env.TMPDIR
  || process.env.TEMP
  || process.cwd()

function TempStack() {
  this.stack = []
}


TempStack.prototype.create = function(type, base) {
  let name = path.join(base,
    'node-watch-' + Math.random().toString(16).substr(2)
  )
  this.stack.push({ name: name, type: type })
  return name
}
TempStack.prototype.write = function(/* file */) {
  for (let i = 0; i < arguments.length; ++i) {
    fs.writeFileSync(arguments[i], ' ')
  }
}
TempStack.prototype.mkdir = function(/* dirs */) {
  for (let i = 0; i < arguments.length; ++i) {
    fs.mkdirSync(arguments[i])
  }
}
TempStack.prototype.cleanup = function(fn) {
  try {
    let temp
    while ((temp = this.stack.pop())) {
      let type = temp.type
      let name = temp.name
      if (type === 'file' && is.file(name)) {
        fs.unlinkSync(name)
      }
      else if (type === 'dir' && is.directory(name)) {
        fs.rmdirSync(name)
      }
    }
  }
  finally {
    if (is.func(fn)) fn()
  }
}

let pending = false

export default function hasNativeRecursive(fn) {
  if (!is.func(fn)) {
    return false
  }
  if (IS_SUPPORT !== undefined) {
    return fn(IS_SUPPORT)
  }

  if (!pending) {
    pending = true
  }
  // check again later
  else {
    return setTimeout(function() {
      hasNativeRecursive(fn)
    }, 300)
  }

  let stack = new TempStack()
  let parent = stack.create('dir', TEMP_DIR)
  let child = stack.create('dir', parent)
  let file = stack.create('file', child)

  stack.mkdir(parent, child)

  let options = { recursive: true }
  let watcher

  try {
    watcher = fs.watch(parent, options)
  } catch (e) {
    if (e.code == 'ERR_FEATURE_UNAVAILABLE_ON_PLATFORM') {
      return fn(IS_SUPPORT = false)
    } else {
      throw e
    }
  }

  if (!watcher) {
    return false
  }

  let timer = setTimeout(function() {
    watcher.close()
    stack.cleanup(function() {
      fn(IS_SUPPORT = false)
    })
  }, 200)

  watcher.on('change', function(evt, name) {
    if (path.basename(file) === path.basename(name)) {
      watcher.close()
      clearTimeout(timer)
      stack.cleanup(function() {
        fn(IS_SUPPORT = true)
      })
    }
  })
  stack.write(file)
}