index.js

'use strict';

const fs = require('fs');
const path = require('path');
const watt = require('gigawatts');

function download(ftp, urlObj, outputFile, callback, callbackProgress) {
  let progress = 0;

  const file = fs.createWriteStream(outputFile);

  watt(function* (next) {
    const total = yield ftp.size(urlObj.pathname, next);
    const stream = yield ftp.get(urlObj.pathname, next);

    yield new Promise((resolve, reject) => {
      stream
        .once('close', function () {
          ftp.end();
        })
        .on('data', function (data) {
          if (!callbackProgress) {
            return;
          }

          progress += data.length;
          callbackProgress(progress, total);
        })
        .on('error', reject)
        .pipe(file)
        .on('finish', function () {
          /* HACK: see xHttp. */
          const fd = fs.openSync(outputFile, 'r');
          fs.closeSync(fd);
          resolve();
        });
    });
  })(callback);
}

exports.get = function (urlObj, outputFile, callback, callbackProgress) {
  const xFs = require('xcraft-core-fs');
  const Ftp = require('ftp');

  xFs.mkdir(path.dirname(outputFile));

  const ftp = new Ftp();

  ftp.on('ready', () => {
    download(ftp, urlObj, outputFile, callback, callbackProgress);
  });

  ftp.connect({
    host: urlObj.hostname,
  });
};

exports.size = watt(function* (urlObj, next) {
  const Ftp = require('ftp');

  const ftp = new Ftp();
  ftp.on('ready', next.parallel());
  ftp.connect({host: urlObj.hostname});
  yield next.sync();

  try {
    return yield ftp.size(urlObj.pathname, next);
  } finally {
    ftp.end();
  }
});