text: const applySourceMap = require('vinyl-sourcemaps-apply');
  const CleanCSS = require('clean-css');
  const path = require('path');
  const PluginError = require('plugin-error');
  const through = require('through2');
  
  module.exports = (options, callback) => {
  
    let _callback = callback || (o => undefined);
  
    return through.obj(function (file, enc, cb) {
  
      let _options = Object.assign({}, options || {});
  
      if (file.isNull()) {
        return cb(null, file);
      }
      if (file.isStream()) {
        this.emit('error', new PluginError('gulp-clean-css', 'Streaming not supported!'));
        return cb(null, file);
      }
  
      if (file.sourceMap) {
        _options.sourceMap = JSON.parse(JSON.stringify(file.sourceMap));
      }
  
      const content = {
        [file.path]: { styles: file.contents ? file.contents.toString() : '' }
      };
      if (!_options.rebaseTo && _options.rebase !== false) {
        _options.rebaseTo = path.dirname(file.path);
      }
  
      new CleanCSS(_options).minify(content, (errors, css) => {
  
        if (errors) {
          return cb(errors.join(' '));
        }
  
        let details = {
          'stats': css.stats,
          'errors': css.errors,
          'warnings': css.warnings,
          'path': file.path,
          'name': file.path.split(file.base)[1]
        };
  
        if (css.sourceMap) {
          details['sourceMap'] = css.sourceMap;
        }
        _callback(details);
  
        file.contents = new Buffer.from(css.styles);
  
        if (css.sourceMap) {
          const iMap = JSON.parse(css.sourceMap);
          const oMap = Object.assign({}, iMap, {
            file: path.relative(file.base, file.path),
            sources: iMap.sources.map(mapSrc => path.relative(file.base, mapSrc))
          });
          applySourceMap(file, oMap);
        }
        cb(null, file);
      });
    });
  };
  