gulpfile.js

"use strict";
const gulp = require('gulp');
const sass = require('gulp-sass')(require('sass'));
const prefix = require('gulp-autoprefixer');
const minify = require('gulp-clean-css');
const rename = require('gulp-rename');
const sourcemaps = require('gulp-sourcemaps');

gulp.task('dev', function () {
    return gulp
        .src('./piment/**/*.scss')
        .pipe(sass())
        .pipe(prefix())
        .pipe(gulp.dest('public/assets/css')); // .css
});

gulp.task('build', function () {
    return gulp
        .src('./piment/**/*.scss')
        .pipe(sourcemaps.init())
        .pipe(sass())
        .pipe(prefix())
        .pipe(gulp.dest('public/assets/css')) // .css
        .pipe(minify())
        .pipe(
            rename(function (path) {
                return {
                    dirname: path.dirname + '',
                    basename: path.basename + '.min',
                    extname: '.css'
                }
            })
        )
        .pipe(sourcemaps.write('.'))
        .pipe(gulp.dest('public/assets/css')); // .min.css
});

gulp.task('watch', function () {
    gulp.watch(['piment/**/*.scss'], gulp.series('dev'))
});

gulp.task("default", gulp.series(['build', 'watch']));