multi depth img sprite

gulpfile.js

var gulp = require('gulp'),
	path = require('path'),
	merge = require('merge-stream'),
	listFilepaths = require('list-filepaths'),
	spritesmith = require('gulp.spritesmith-multi');

// 자동 스프라이트
gulp.task('auto-sprite', function() {
	var stream = merge();

	listFilepaths('./src/img-sprites')
		.then(filepaths => {
			const dirs = [
				// get unique array 
				...new Set(
					// filepath map loop
					// [ ~~/dir/two/one/file.png, ... ]
					// => [ ~~/dir/two, ... ]
					filepaths.map(v => {
						var dir = v.split(path.sep);
						dir.pop();
						dir.pop();
						dir = dir.join(path.sep);
						dir = path.relative('./src/img-sprites', dir);

						return dir;
					})
				)
			];

			return dirs;
		})
		.catch(console.error)
		.then(function(dirs) {
			dirs.forEach(function(dir, index) {
				var spriteData = gulp.src(`./src/img-sprites/${dir}/**/*.png`)
					.pipe(spritesmith({
						spritesmith: function (options, sprite, icons){
							options.imgPath =  `@@img/sprite/${options.imgName}`;
							options.cssName = `_${sprite}-sprite.scss`;
							options.cssTemplate = null;
							options.cssSpritesheetName = sprite;
							options.padding = 10;
							options.cssVarMap = function(sp) {
								sp.name = `${sprite}-${sp.name}`;
							};

							return options;
						}
					}))
					.on('error', function (err) {
						console.log(err)
					});

				var imgStream = spriteData.img.pipe(gulp.dest(`./dist/images/${dir}/sprite`));
				var cssStream = spriteData.css.pipe(gulp.dest(`./src/scss/${dir}/vendors`));

				stream.add(imgStream);
				stream.add(cssStream);
			});
		});

	return stream;
});