dropbox-downloader.js

const RateLimiter = require('limiter').RateLimiter;

var limiters = {};

function getLimiter(accessToken) {
  let limiter = limiters[accessToken] = limiters[accessToken] || new RateLimiter(10, 'second');
  return limiter;
}

function download(accessToken, src, dst) {
  return new Promise((resolve, reject) => {
    getLimiter(accessToken).removeTokens(1, function() {
      let dl = https.request({
        method: 'POST',
        hostname: 'content.dropboxapi.com',
        port: 443,
        path: '/2/files/download',
        agent: myAgent,
        headers: {
          'Authorization'  : 'Bearer ' + accessToken,
          'Dropbox-API-Arg': JSON.stringify({path: src})
        }
      }, function(resp) {
        if (resp.statusCode !== 200) {
          log.info('ERROR: Download failed for ', resp.statusCode, src, dst, resp.headers);
          return reject(new Error('Dropbox return bad HTTP code for download', resp.statusCode));
        }
        let parent = path.dirname(dst);
        fse.mkdirp(parent, function(err) {
          if (err) {
            log.error('Could not create directory', parent, err);
            return reject('Could not create directory');
          }
          let dstStrm = fs.createWriteStream(dst);

          resp.pipe(dstStrm);

          resp.on('error', e => {
            reject(new Error('Download read stream error', e));
          });

          resp.on('end', () => {
            dstStrm.destroy();
            log.info('dl complete', dstStrm.bytesWritten, resp.headers['content-length']);
            resolve(resp);
          });
        });
      });
      dl.end();
    });
  });
}