gulpfile.js

var gulp = require('gulp'),
  yargs = require('yargs/yargs'),
  argv = yargs(process.argv.slice(2)).argv,
  dartSass = require('sass'),
  sass = require('gulp-sass')(dartSass),
  sassVariables = require('gulp-sass-variables'),
  fs = require('fs'),
  manifestBuilder = require('./src/js/util/manifest-builder');

var supportedTargets = require('./build/targets');
if (!argv.target || supportedTargets.indexOf(argv.target) === -1) {
  console.error(`Target is required. Please use one of the following targets: ${supportedTargets.join(', ')}. Example usage: gulp [task-name] --target=chrome`);
  process.exit(1);
}

var buildVersion = argv.buildVersion;
if (typeof buildVersion === 'undefined' || buildVersion === null || buildVersion === "") {
  buildVersion = require('./package.json').version;
}

gulp.task('sass-ui', function () {
  return gulp.src('src/sass/ui/*.scss')
    .pipe(sassVariables({
      $target: argv.target
    }))
    .pipe(sass({
      outputStyle: 'compressed'
    }).on('error', sass.logError))
    .pipe(gulp.dest(`dist/${argv.target}/ui/css`));
});

gulp.task('js-ui', function () {
  return gulp.src(['src/js/ui/*.js', 'src/assets/lib/*.js'])
    .pipe(gulp.dest(`dist/${argv.target}/ui/js`));
});

gulp.task('html-ui', function () {
  return gulp.src(['src/html/ui/*.htm?(l)'])
    .pipe(gulp.dest(`dist/${argv.target}/ui`));
});

gulp.task('img', function () {
  return gulp.src(['src/assets/img/**/*'])
    .pipe(gulp.dest(`dist/${argv.target}/img`));
});

gulp.task('js', function () {
  return gulp.src(['src/js/*.js'])
    .pipe(gulp.dest(`dist/${argv.target}/js`));
});

gulp.task('ui', gulp.series(gulp.parallel('html-ui', 'js-ui', 'sass-ui')));

gulp.task('manifest', gulp.series(gulp.parallel('ui', 'img', 'js'), function (cb) {
  var manifest = manifestBuilder.build(argv.target, buildVersion);
  var manifestJson = JSON.stringify(manifest, null, 3);
  return fs.writeFile(`dist/${argv.target}/manifest.json`, manifestJson, cb)
}));

gulp.task('build', gulp.series(gulp.parallel('manifest', 'ui', 'img', 'js')));
gulp.task('default', gulp.series('build'));