Async Parallel Image Processing

AsyncIP.coffee

mongoose              = require "mongoose"
Busboy                = require "busboy"
secrets               = require "../config/secrets"
GridStream            = require "gridfs-stream"
Files                 = require "../models/files"
sharp                 = require "sharp"
async                 = require "async"



# POST files
# process the uploaded file with nodeJS stream module == Busboy
# pass this file stream from busboy to MongoDB GridFS using mongoose 
# gridfs-stream 'writestream',
# Then, using  Async.parallel for image processing.
# save multiple resized copies: 'raw', 'desktop', 'tablet', 'mobile', thumb'

exports.mongodbUpload = (req, res, next) ->
  FIELDS          = ['title','tag']
  fieldValues     = {}

  gridStream = new GridStream(mongoose.connection.db, mongoose.mongo)

  busboy = new Busboy
    headers: req.headers
    limits:
      fileSize:   1024 * 1024 * 15
      files:      1

  #busboy field event
  busboy.on 'field', (fieldname, val, fieldNameTrunc, valTrunc) ->
    if fieldname in FIELDS
      fieldValues[fieldname] = val

  #busboy file event
  busboy.on "file", (fieldname, stream, filename, encoding, mimetype) ->
    async.parallel
      raw: (done) ->
        writestream = gridStream.createWriteStream
          mode:           "w"
          filename:       filename
          content_type:   mimetype
          metadata:
            userid:       req.user._id
            fields:       fieldValues
            encoding:     encoding
            size:         'raw'

        writestream.on 'error', (err) ->
          done err, msg: 'error'

        writestream.on "close", (file) ->
          done null, file

        stream.pipe writestream

      desktop: (done) ->
        transformer = sharp()
          .resize 1920,1080
          .crop sharp.gravity.north

        writestream = gridStream.createWriteStream
          mode:           "w"
          filename:       filename
          content_type:   mimetype
          metadata:
            userid:       req.user._id
            fields:       fieldValues
            encoding:     encoding
            size:         'desktop'

        writestream.on 'error', (err) ->
          done err, msg: 'error'

        writestream.on "close", (file) ->
          done null, file

        stream.pipe(transformer).pipe(writestream) 

      tablet: (done) ->
        transformer = sharp()
          .resize 1024,768
          .crop sharp.gravity.north

        writestream = gridStream.createWriteStream
          mode:           "w"
          filename:       filename
          content_type:   mimetype
          metadata:
            userid:       req.user._id
            fields:       fieldValues
            encoding:     encoding
            size:         'tablet'

        writestream.on 'error', (err) ->
          done err, msg: 'error'

        writestream.on "close", (file) ->
          done null, file

        stream.pipe(transformer).pipe(writestream) 

      mobile: (done) ->
        transformer = sharp()
          .resize 480,320
          .crop sharp.gravity.north

        writestream = gridStream.createWriteStream
          mode:           "w"
          filename:       filename
          content_type:   mimetype
          metadata:
            userid:       req.user._id
            fields:       fieldValues
            encoding:     encoding
            size:         'mobile'

        writestream.on 'error', (err) ->
          done err, msg: 'error'

        writestream.on "close", (file) ->
          done null, file

        stream.pipe(transformer).pipe(writestream) 

      thumb: (done) ->
        transformer = sharp()
          .resize 64,64
          .crop sharp.gravity.north

        writestream = gridStream.createWriteStream
          mode:           "w"
          filename:       filename
          content_type:   mimetype
          metadata:
            userid:       req.user._id
            fields:       fieldValues
            encoding:     encoding
            size:         'thumb'

        writestream.on 'error', (err) ->
          done err, msg: 'error'

        writestream.on "close", (file) ->
          done null, file

        stream.pipe(transformer).pipe(writestream) 

    , (err, result) ->
      return res.status(500).json() if err
      # transMutateReconfig into our fileMap
      fileMap =
        tag:        result.raw.metadata.fields.tag
        title:      result.raw.metadata.fields.title
        raw:        result.raw._id
        desktop:    result.desktop._id
        tablet:     result.tablet._id
        mobile:     result.mobile._id
        thumb:      result.thumb._id

      # addFile will add the mongo _id via result  
      req.user.addFile fileMap, (err, result) ->
        return res.status(503).json() if err
        #created 201
        res.status(201).json(newFile: result) # client will newFile prop with


  busboy.on "finish", -> # returns async
    req.user.fileCacheTime = Date.now()

  busboy.on "error", (err)-> # returns async

  req.pipe busboy