import { extractDomainFromUrl } from 'discourse/lib/utilities';
import { h } from 'virtual-dom';

const _decorators = [];

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

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

  if (!href) { return; }

  let domain = extractDomainFromUrl(href);
  if (!domain) { return; }

  // www appears frequently, so we truncate it
  if (domain && domain.substr(0, 4) === 'www.') {
    domain = domain.substring(4);
  }

  const meta = { target, href, 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);
  }
}