Gulp partially remove directories structure

My directories structure is similar to this:

app/
  directory1/
    assets/
      images/
      js/
  directory2/
    assets/
      images/
dist/
  assets/
    images/
    js/

What I try to achieve using Gulp is to "gather" assets from directories 1, 2, ... and place them into the dist/assets/ so I wrote this:

gulp.task('gather-assets', function() {
  gulp.src('app/*/assets/**').pipe(gulp.dest('dist/assets/'));
});

The problem is that after running this function it will create a path like this:

dist/assets/directory1/assets/images

Following the recommendations from this question I tried to use gulp-rename, but my case is different, and if I use gulp-rename like this:

gulp.task('gather-assets', function() {
  gulp.src('app/*/assets/**').pipe(rename({dirname: ''})).pipe(gulp.dest('dist/assets/'));
});

it will surely remove unnecessary path at the place of * asterisk, but it will remove the ** path as well. So files from both images/ and js/ will be copied to assets/ without subdirectories. What solution is available for me for this scenario?

Solution

Gulp-flatten will work for you.

var flatten = require('gulp-flatten');

gulp.task('gather-assets', function() {

  return  gulp.src('app/*/assets/**')
    //  .pipe(rename({ dirname: '' }))

    // -2 will keep the last two parents : assets/images or assets/js
   .pipe(flatten({ includeParents: -2 }))

   .pipe(gulp.dest('dist'));
});

And if you wanted to use gulp-rename: [both gulp-flatten and gulp-rename are just doing string manipulations of each file's directory structure]

 //   .pipe(flatten({ includeParents: -2 }))

 .pipe(rename(function (file) {

    let tempArray = file.dirname.split(path.sep);

    // remove the first array item : directory1 or directory2
    // rejoin the remaining array items into a directory string

    let temp = tempArray.slice(1).join(path.sep);

    file.dirname = temp;
  }))