import { h } from 'virtual-dom';

const _decorators = [];

export function addFeaturedLinkMetaDecorator(decorator) {
  _decorators.push(decorator);
}

export function extractLinkMeta(topic) {
  const href = topic.get('featured_link');
  const target = Discourse.User.currentProp('external_links_in_new_tab') ? '_blank' : '';

  if (!href) { return; }

  const meta = {
    target: target,
    href,
    domain: topic.get('featured_link_root_domain'),
    rel: 'nofollow'
  };

  if (_decorators.length) {
    _decorators.forEach(cb => cb(meta));
  }

  return meta;
}

export default function renderTopicFeaturedLink(topic) {
  const meta = extractLinkMeta(topic);
  if (meta) {
    return `<a class="topic-featured-link" rel="${meta.rel}" target="${meta.target}" href="${meta.href}">${meta.domain}</a>`;
  } else {
    return '';
  }
};

export function topicFeaturedLinkNode(topic) {
  const meta = extractLinkMeta(topic);
  if (meta) {
    return h('a.topic-featured-link', {
      attributes: { href: meta.href, rel: meta.rel, target: meta.target }
    }, meta.domain);
  }
}