figure out how to write file from src/dir file/dir status

file_util.js

// figures out how to write the file based on source, destination
// eg
// source = a/f.jpg
// dest = /tmp
// result = /tmp/f.jpg
//
// source = a/f.jpg
// dest = tmp/g.jpg
// result = tmp/g.jpg
function getWritePathFromSource(source, destination, callback) {
   var path = require('path')
   var fs = require('fs')

  path.exists(destination, function(err, exists) {
    if (exists) {
      fs.stat(destination, function(stat) {
        stat.isFile(function(err, isFile) {
          if (isFile) {
            callback(null, path.normalize(destination))
          } else {
            var filename = path.basename(source)
            callback(null, path.join(destination,filename))
          }
        })
      })
    } else {
      if (path.extname(destination) === '') {
        var filename = path.basename(source)
        callback(null, path.join(destination, filename))
      } else {
        callback(null, path.normalize(destination))
      }
    }
  })
}