filemanager.js

const path = require('path')
const fileType = require('file-type')
const base64 = require('base64-arraybuffer')
const crypto = require('crypto')
const makeDir = require('make-dir')
const fs = require('co-fs')

const defaultOptions = {
  pathStorage: '.',
  algorithm: 'md5',
  exclude: '',
  extension: ['png', 'jpg', 'jpeg'],
}

const makeHash = (content, algo) => crypto
  .createHash(algo)
  .update(content)
  .digest('hext')

const writeFile = (filePath, binary) => fs.writeFile(filePath, binary, 'base64')

async function saveFile(original, inputOptions = defaultOptions) {
  const options = Object.assign({}, defaultOptions, inputOptions)

  const content = original.replace(/^data:.+;base64,/, '')
  const arrayBuff = base64.decode(content)
  const type = fileType(arrayBuff)

  if (type == null || options.extension.indexOf(type.ext) === -1) {
    throw new Error('File type is not supported')
  }

  const hash = makeHash(content)

  const rootDir = hash.substring(0, 2)
  const subDir = hash.substring(2, 4)

  const dir = path.join(options.pathStorage, rootDir, subDir)
  const filePath = path.join(dir, `${hash}.${type.ext}`)

  try {
    await makeDir(dir)
    await writeFile(filePath, content)
  }
  catch (error) {
    throw new Error('Cannot save file', error)
  }

  if (options.exclude) {
    return filePath.replace(options.exclude, '')
  }

  return filePath
}