fs-write-worker-copy.js

// @flow

import { ncp } from "graceful-ncp";
import progress from "progress-stream";
import getSize from "get-folder-size";
import fs from "mz/fs";
import * as c from "../fs-write-constants";
import * as t from "../fs-write-actiontypes";

import type { WriteStream, ReadStream } from "fs";
import type { SubTask, ProgressReport } from "../fs-write-types";

export default function copy(
  subTask: SubTask,
  handleProgress: (progress: ProgressReport) => void
): Promise<*> {
  var fullSize = 1;
  var progressPerFileStack = [];
  var calcProgress = () => {
    // Combine each progress to a full value
    var fullProgress = 0;
    progressPerFileStack.forEach(bytes => {
      fullProgress = fullProgress + bytes;
    });
    handleProgress({
      destination: subTask.destination,
      percentage: Math.round(fullProgress / fullSize * 100)
    });
  };

  var ncpOptions = {
    stopOnErr: true,
    clobber: subTask.clobber,
    limit: 16,
    transform: (read: ReadStream, write: WriteStream) => {
      // Insert Progress report in ncp stream
      // For every file in ncp

      var id = progressPerFileStack.length;
      progressPerFileStack[id] = 0;
      var str = progress({
        time: 100
      }).on("progress", progress => {
        progressPerFileStack[id] = progress.transferred;
        calcProgress();
      });
      read.pipe(str).pipe(write);
    }
  };

  return new Promise((resolve, reject) => {
    getSize(subTask.source, (err, size) => {
      if (err) {
        reject(err);
        return;
      }
      fullSize = size;
      ncp(subTask.source, subTask.destination, ncpOptions, errList => {
        if (errList) {
          reject(errList[0]);
          return;
        }
        resolve();
      });
    });
  });
}