window.onload = async function(){
  let locationHref = new URL(location.href);
  let node = locationHref.searchParams.get('node')
  let pubsub = locationHref.searchParams.get('pubsub')

  // Set button follow
  let follow = document.querySelector('#follow');
  if (follow) {
    //let feedUrl = location.href.replace(/^https?:/, 'feed:');
    let feedUrl = `feed://${location.host}/atom?pubsub=${pubsub}&node=${node}`;
    follow.href = feedUrl;
    follow.addEventListener ('click', function() {
        window.open(feedUrl, "_self");
    });
    // Fix button subtome
    document.querySelector('#subtome').href='https://www.subtome.com/#/subscribe?feeds=' + feedUrl;
  }

  // Convert ISO8601 To UTC
  for (let element of document.querySelectorAll(
    '#articles > ul > li > div > h4.published,' +
    '#articles > ul > li > div > h4.updated, ' +
    '#feed > #header > h2#subtitle.date')) {
    let timeStamp = new Date(element.textContent);
    element.textContent = timeStamp.toUTCString();
  }

  // Parse Markdown
  for (let element of document.querySelectorAll('#articles div[type="text"]')) {
    element.innerHTML = marked.parse(element.textContent);
  }

  // NOTE Report this issue to Movim. See node "deltachat" of pubsub "news.movim.eu".
  for (let element of document.querySelectorAll('#articles div[type="html"]')) {
    if (!element.children.length) {
      element.innerHTML = marked.parse(element.textContent);
    }
  }

  /*

  NOTE

  The reason for the following code to parse HTML inside an software which
  already parses HTML, is that some people who influence the so called Gecko
  HTML Engine product (mostly people from the advertisement industry with whom
  I shamefully used to work with) have intentions to eliminate standards and
  technologies such as Syndication (Atom/RDF/RSS), XSLT and many other
  technologies that actually empower people and their privacy.

  Recently, some changes were made to the XSLT parser of Gecko which result in
  noncompliance with the XSLT standard.

  The XSLT feature that was removed is "disable-output-escaping" which upon the
  value "yes" the XSLT engine should transform and treat a subject string into
  HTML, yet the Gecko HTML Engine ignores this XSLT direction.

  This change was probably made in order to:
  * Frustrate new XSLT developers; or
  * Influence new XSLT developers to think that XSLT has a limited set of
    features and believing of some sort of inability to parse HTML from a
    retrieved HTML string; and
  * Consequently cause developers to abstain from using the XSLT technology.

  Do not use HTML browsers or use Ladybird, Pale Moon or browsers that are
  powered by KHTML (WebKit) instead of anti-privacy software such as Chromium
  and Gecko.

  */

  // Parse HTML
  //if (navigator.userAgent.includes(') Gecko/')) {
  //  for (let element of document.querySelectorAll('#articles div[type="html"]')) {
  //    element.innerHTML = element.textContent;
  //  }
  //}
  for (let element of document.querySelectorAll('#articles div[type="html"]')) {
    if (!element.children.length) {
      element.innerHTML = element.textContent;
    }
  }

  // Build a journal list
  if (locationHref.pathname.startsWith('/atom') && node) {
    itemsList = await openJson(node)
    if (itemsList && locationHref.searchParams.get('item')) {
      node = locationHref.searchParams.get('node')
      pubsub = locationHref.searchParams.get('pubsub')
      let elementDiv = document.createElement('div');
      elementDiv.id = 'journal';
      let elementH3 = document.createElement('h3');
      elementH3.textContent = 'Journal';
      elementDiv.appendChild(elementH3);
      let elementH4 = document.createElement('h4');
      elementH4.textContent = node;
      elementDiv.appendChild(elementH4);
      let elementUl = document.createElement('ol');
      elementDiv.appendChild(elementUl);
      for (let item of itemsList) {
        let elementLi = document.createElement('li');
        let elementA = document.createElement('a');
        elementA.textContent = item.title;
        elementA.href = item.link;
        elementLi.appendChild(elementA);
        elementUl.appendChild(elementLi);
      }
      let elementB = document.createElement('b');
      elementB.textContent = 'Actions';
      elementDiv.appendChild(elementB);
      let elementUl2 = document.createElement('ul');
      elementDiv.appendChild(elementUl2);
      links = [
        {'text' : 'Subscribe from an XMPP client.',
         'href' : `xmpp:${pubsub}?pubsub;action=subscribe;node=${node}`},
        {'text' : 'Subscribe with a News Reader.',
         'href' : `feed://${location.host}/atom?pubsub=${pubsub}&node=${node}`},
        {'text' : 'Browse the journal.',
         'href' : `atom?pubsub=${pubsub}&node=${node}`},
        {'text' : 'Browse the portal.',
         'href' : `opml?pubsub=${pubsub}`}
         ]
      for (let link of links) {
        let elementLi = document.createElement('li');
        let elementA = document.createElement('a');
        elementA.textContent = link.text;
        elementA.href = link.href;
        elementLi.appendChild(elementA);
        elementUl2.appendChild(elementLi);
      }
      elementDiv.appendChild(elementUl2);
      // document.querySelector('#feed').appendChild(elementDiv); // This would result in a combination of Title, Article, and Journal
      document.querySelector('#articles').appendChild(elementDiv);
    }
  }

  // Convert URI xmpp: to URI http: links.
  for (let xmppLink of document.querySelectorAll(
    '#articles h3 > a[href^="xmpp:"][id^="rivista-"],' +
    '#articles h5.related > a[class^="rivista-"],' +
    '#journal > ol > li > a[href^="xmpp:"]')) {
    xmppUri = new URL(xmppLink);
    let parameters = xmppUri.search.split(';');
    try {
      try {
        let node = parameters.find(parameter => parameter.startsWith('node=')).split('=')[1];
        let item = parameters.find(parameter => parameter.startsWith('item=')).split('=')[1];
        let pubsub = xmppUri.pathname;
        xmppLink.href = `atom?pubsub=${pubsub}&node=${node}&item=${item}`
      } catch {
        let node = parameters.find(parameter => parameter.startsWith('node=')).split('=')[1];
        let pubsub = xmppUri.pathname;
        xmppLink.href = `atom?pubsub=${pubsub}&node=${node}`
      }
    } catch (err) {
      console.warn(err)
    }
  }

  // Display a selection of suggested software.
  const selection = {
    'akregator' : {
      'name'  : 'Akregator',
      'image' : 'akregator.svg',
      'url'   : 'https://apps.kde.org/akregator/'
    },
    'leechcraft' : {
      'name'  : 'LeechCraft',
      'image' : 'leechcraft.png',
      'url'   : 'https://leechcraft.org/'
    },
    'liferea' : {
      'name'  : 'Liferea',
      'image' : 'liferea.svg',
      'url'   : 'https://lzone.de/liferea/'
    },
    'raven' : {
      'name'  : 'Raven Reader',
      'image' : 'raven.svg',
      'url'   : 'https://ravenreader.app/'
    },
    'rssguard' : {
      'name'  : 'RSS Guard',
      'image' : 'rssguard.png',
      'url'   : 'https://github.com/martinrotter/rssguard'
    },
    'rssowl' : {
      'name'  : 'RSSOwl',
      'image' : 'rssowl.svg',
      'url'   : 'http://www.rssowl.org/'
    },
    'tickr' : {
      'name'  : 'TICKR',
      'image' : 'tickr.png',
      'url'   : 'https://www.open-tickr.net/'
    }
  }
  let selectionLink = document.querySelector('#selection-link');
  selectionLink.addEventListener ('click', function() {
    let elementDiv = document.createElement('div');
    elementDiv.id = 'selection-page';
    let elementH1 = document.createElement('h1');
    elementH1.textContent = 'Select A News Reader';
    elementDiv.appendChild(elementH1);
    let elementH2 = document.createElement('h2');
    elementH2.textContent = 'Install A Feed Reader For Desktop And Mobile';
    elementDiv.appendChild(elementH2);
    const brands = Object.keys(selection);
    let elementDivSel = document.createElement('div');
    elementDivSel.id = 'selection';
    for (let i = 0; i < brands.length; i++) {
      let brand = brands[i];
      let elementSpan = document.createElement('span');
      let elementA = document.createElement('a');
      elementA.href = selection[brand].url;
      elementA.textContent = selection[brand].name;
      let elementImg = document.createElement('img');
      elementImg.src = 'graphic/' + selection[brand].image;
      elementSpan.appendChild(elementImg);
      elementSpan.appendChild(elementA);
      elementDivSel.appendChild(elementSpan);
      elementDiv.appendChild(elementDivSel);
    }
    let elementP1 = document.createElement('p');
    elementP1.textContent = '' +
      'This is a selection of desktop, mobile and HTML (sometimes referred to ' +
      'as "online") News Readers for you to choose from.';
    elementDiv.appendChild(elementP1);
    let elementP2 = document.createElement('p');
    elementP2.textContent = '' +
      'This selection includes: Podcast Managers, Torrent ' +
      'Clients, Chat Bots, HTML Browsers and Plugins which support ' +
      'syndication feeds.';
    elementDiv.appendChild(elementP2);
    let elementSpan = document.createElement('span');
    elementSpan.id = 'return';
    elementSpan.textContent = 'Return To PubSub';
    elementSpan.addEventListener ('click', function() {
      document.querySelector('#selection-page').remove();
    });
    elementDiv.appendChild(elementSpan);
    document.body.appendChild(elementDiv);
  });
}

async function openJson(nodeId) {
  return fetch(`/data/${nodeId}.json`)
  .then(response => {
     if (!response.ok) {
       throw new Error('HTTP Error: ' + response.status);
     }
     return response.json();
  })
  .then(json => {
    return json;
  })
  .catch(err => {
    console.warn(err);
  })
}