text: // # link_class helper
  const {config} = require('../services/proxy');
  const {SafeString, localUtils} = require('../services/rendering');
  
  const _ = require('lodash');
  const errors = require('@tryghost/errors');
  const tpl = require('@tryghost/tpl');
  
  const {buildLinkClasses} = localUtils;
  
  const messages = {
      forIsRequired: 'The {{link_class}} helper requires a for="" attribute.'
  };
  
  module.exports = function link_class(options) { // eslint-disable-line camelcase
      options = options || {};
      options.hash = options.hash || {};
      options.data = options.data || {};
  
      // If there is no for provided, this is theme dev error, so we throw an error to make this clear.
      if (!_.has(options.hash, 'for')) {
          throw new errors.IncorrectUsageError({
              message: tpl(messages.forIsRequired)
          });
      }
  
      // If the for attribute is present but empty, this is probably a dynamic data problem, hard for theme devs to track down
      // E.g. {{link_class for=slug}} in a context where slug returns an empty string
      // Error's here aren't useful (same as with empty get helper filters) so we fallback gracefully
      if (!options.hash.for || options.hash.for.string === '') {
          options.hash.for = '';
      }
  
      let href = options.hash.for.string || options.hash.for;
      let classes = buildLinkClasses(config.get('url'), href, options);
  
      return new SafeString(classes.join(' '));
  };
  