index.js

import IO from 'socket.io-client';
import Promise from 'bluebird';
import streamToPromise from 'stream-to-promise';
import fs from 'fs';

const io = IO('http://localhost:3000', {
  reconnect: true
});

export default (() => {

  io.on('error', (err) => {
    console.log('error: ', err);
  });

  io.on('connect', () => {
    console.log('>>>>>>> socket connected');

    const apiInit = (file_info) => {
      return new Promise((resolve) => {
        io.emit('upload', {
          upload_phase: 'start',
          file_size: file_info.size
        }, (res) => resolve(res));
      });
    };

    const apiFinish = () => {
      return new Promise((resolve) => {
        io.emit('upload', {
          upload_phase: 'finish'
        }, (res) => resolve(res));
      });
    };

    const uploadChunk = (start, end, chunk, snapshot_id) => {
      const opts = {
        upload_phase: 'transfer',
        start_offset: start,
        end_offset: end,
        snapshot_id: snapshot_id,
        chunk: chunk
      };

      return new Promise((resolve) => {
        io.emit('upload', opts, (res) => resolve(res));
      });
    };

    const uploadChain = (buffer, res) => {
      if (res.start_offset === res.end_offset) { return res; }

      const chunk = buffer.slice(res.start_offset, res.end_offset);
      return uploadChunk(res.start_offset, res.end_offset, chunk, res.snapshot_id)
      .then((res) => uploadChain(buffer, res));
    };

    const apiUpload = (args) => {
      const fileInfo = fs.statSync(args.file_path);
      const stream = fs.createReadStream(args.file_path, { defaultEncoding: 'utf8' });

      return Promise.resolve(streamToPromise(stream))
        .then((buffer) => [buffer, apiInit(fileInfo, args.snapshot_id)])
        .spread((buffer, res) => uploadChain(buffer, res))
        .then(() => apiFinish());
    };

    return apiUpload({
      snapshot_id: '57ac622940d0c1788936c39b',
      file_path: __dirname + '/test.img' //path to file to upload
    })
    .then((res) => {
      console.log('res: ', res);
    })
    .catch((e) => {
      console.error(e);
    });

  });

})();