gulpfile.js

var gulp = require('gulp'),
    sass = require('gulp-sass');
    sourcemap = require('gulp-sourcemaps'),
        rtlcss = require("gulp-rtlcss"),
        rename = require("gulp-rename"),
        gulpfilter = require('gulp-filter');


/* sass compiler */
function compileSass(src, dest){
    return function(){
        gulp.src(src)
            .pipe(sourcemap.init())
            .pipe(sass({ outputStyle: 'expanded' }).on('error', sass.logError))
            .pipe(sourcemap.write('map'))
            .pipe(gulp.dest(dest))
    }
}

// compile bootstrap
gulp.task('bs', compileSass('public/assets/bootstrap/bootstrap.scss', 'public/assets/css/'));
gulp.task('style', compileSass('public/assets/scss/style.scss','public/assets/css/'));
gulp.task('admin', compileSass('public/assets/scss/admin/style.scss','admin/assets/css/'));

// default gulp task\
gulp.task('default',['bs', 'style', 'admin'], function(){
    gulp.watch('public/assets/bootstrap/*.scss', ['bs']);
    gulp.watch('public/assets/scss/**/*.scss', ['style']);
    gulp.watch('public/assets/scss/admin/**/*.scss', ['admin']);
});

//rtl css generator
gulp.task('rtl', function () {
    var bootstrap = gulpfilter('**/bootstrap.css', {restore: true}),
        style = gulpfilter('**/style.css', {restore: true}),
        search_style = gulpfilter('**/search-style.css', {restore: true});

    gulp.src(['public/assets/css/bootstrap.css', 'public/assets/css/style.css', 'public/assets/css/search-style.css'])
        .pipe(rtlcss({
            'stringMap': [
                {
                    'name': 'left-right',
                    'priority': 100,
                    'search': ['left', 'Left', 'LEFT'],
                    'replace': ['right', 'Right', 'RIGHT'],
                    'options': {
                        'scope': '*',
                        'ignoreCase': false
                    }
                },
                {
                    'name': 'ltr-rtl',
                    'priority': 100,
                    'search': ['ltr', 'Ltr', 'LTR'],
                    'replace': ['rtl', 'Rtl', 'RTL'],
                    'options': {
                        'scope': '*',
                        'ignoreCase': false
                    }
                }
            ]
        }))
        .pipe(bootstrap)
        .pipe(rename({suffix: '-rtl', extname: '.css'}))
        .pipe(gulp.dest('public/assets/css/'))
        .pipe(bootstrap.restore)

        .pipe(style)
        .pipe(rename({suffix: '-rtl', extname: '.css'}))
        .pipe(gulp.dest('public/assets/css/'))
        .pipe(style.restore)

        .pipe(search_style)
        .pipe(rename({suffix: '-rtl', extname: '.css'}))
        .pipe(gulp.dest('public/assets/css/'))
        .pipe(search_style.restore)
});