var fs  = require('fs')
var path = require('path')

var copyFile = function(srcPath, tarPath, cb) {
 var rs = fs.createReadStream(srcPath)
 rs.on('error', function(err) {
  if (err) {
   console.log('read error', srcPath)
  }
  cb && cb(err)
 })

 var ws = fs.createWriteStream(tarPath)
 ws.on('error', function(err) {
  if (err) {
   console.log('write error', tarPath)
  }
  cb && cb(err)
 })
 ws.on('close', function(ex) {
  cb && cb(ex)
 })

 rs.pipe(ws)
}

var copyFolder = function(srcDir, tarDir, cb) {
 fs.readdir(srcDir, function(err, files) {
  var count = 0
  var checkEnd = function() {
   ++count == files.length && cb && cb()
  }

  if (err) {
   checkEnd()
   return
  }

  files.forEach(function(file) {
   var srcPath = path.join(srcDir, file)
   var tarPath = path.join(tarDir, file)

   fs.stat(srcPath, function(err, stats) {
    if (stats.isDirectory()) {
     console.log('mkdir', tarPath)
     fs.mkdir(tarPath, function(err) {
      if (err) {
       console.log(err)
       return
      }

      copyFolder(srcPath, tarPath, checkEnd)
     })
    } else {
     copyFile(srcPath, tarPath, checkEnd)
    }
   })
  })

  //为空时直接回调
  files.length === 0 && cb && cb()
 })
}

copyFolder('...', '....', function(err) {
 if (err) {

  return
 }

 //continue
})