fast busboy s3 video upload

                                                 /* ----- GENERAL ARCHITECTURE--->

                                                 not valid
                                                <-respond with error
                                                            |
                                                            |
                                                            |
                                                            |
         +------------------------------------------------------------------------+
         |                      FFMPEG                      |                     |
         +------------------------------------------------------------------------+
                                                            |
                                                            |
                busboy                                      |
               +------------------------------------------> |
               |  optimistically retrieve enough bytes      |
               |  of file to check if valid image frame     | valid
               |                                            |
multipart------+--------------------------------------------v-------------stream of frames+---------+---------->
upload                                                                                              ^    200 ok with file location from s3
                                                                                                    |      (finished video processing)
                                                                                                    |
                                             +------------------+----+-----------------+------------^
                                             |  upload          |    |  transcode      |
                                             |  to s3           |    |  transform      |
                                             |                  |    |                 |
                                             |                  |    |                 |
                                             +-----------+------+    +-----------------+
                                                         |
                                                         |
                                                   SSE   |
                                                         |
                                                         |
                                                         |
                                                         +--^--------------
                                                            (file is ready and uploaded into s3)

--- GENERAL ARCHITECTURE---> */
export async function uploadVideo(req, resFromNode) {
  const user = req.user;
  var fsImpl = new S3FS('instaclone9753', {
    accessKeyId: 'AKIAIXA5AKJQB7C3ZHCQ',
    secretAccessKey: '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'
  });

  req.busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {

    const imageFrames = [];

    const bufferHandler = (chunk) => {
      //change this to optimistically calculate number of bytes necessary needed to retrieve metadata and offload an appropriate buffer
      if (Buffer.concat(imageFrames).length < 4000000) {
        imageFrames.push(chunk);
      } else {
        file.removeListener('data', bufferHandler);
        imageFrames.push(chunk);
        file.pause();
        file.unshift(Buffer.concat(imageFrames));
        checkIfStreamValid(imageFrames, (err, res) => {
          if (err) {
            resFromNode.header('Connection', 'close');
            return resFromNode.status(415).json("This file has not met the standards");
          }
          // if file is valid call unshift put the data back on the stream and then pipe it into s3

          const key = crypto.randomBytes(10).toString('hex');
          const hashFilename = key + '-' + filename;
          const params = {
            Bucket: fsImpl.bucket,
            Key: hashFilename,
            Body: file,
            ContentType: "video/mp4"
          };



          //finally uploaded either the transformed or the original stream
          fsImpl.s3.upload(params, function (err, data) {
            console.log(err, data, "YO!")
            resFromNode.json({
              "success": true,
              "payload": data.Location
            });
          }).on('httpUploadProgress', function (evt) {
            console.log(evt);
            pubsub.emit('uploadProgress', evt);
          })
        });
      }
    }

    const listener = file.on('data', bufferHandler);
    file.on('end', () => console.log("finished! buffering into memory!"));

    function checkIfStreamValid(pseudoStream, cb) {
      //use ffmpeg here to check if it is a valid video file;
      const pseudoBuffer = Buffer.concat(pseudoStream)
      console.log(pseudoBuffer);
      const bufferStream = new PassThrough();

      // Write your buffer
      bufferStream.end(pseudoBuffer);

      ffmpeg.ffprobe(bufferStream, function (err, metadata) {
        if (metadata) cb(null, metadata);
        console.log(err);
        if (err) cb(true, null);
      });
    }

  });
  req.pipe(req.busboy);

}