msglist = Array.from(document.querySelectorAll('.msg-list')).find(list => list.querySelectorAll('.card').length > 10);
messages = Array.from(msglist.querySelectorAll('.card'));

threaded = [];
messages_by_id = {};

messages.reverse().forEach((message) => {
  let id = message.querySelector('.msg-head-author .msg-num').textContent.trim();

  messages_by_id[id] = message;

  let parentid = message.querySelector('.msg-head-replied .msg-num');

  if (parentid)
  {
    let parent = threaded.find(messages => messages.includes(parentid.textContent.trim()));

    if (parent)
    {
      parent.push(id);
      threaded = threaded.filter(item => item != parent)
      threaded.push(parent);
    }
    else
      threaded.push([id]);
  }
  else
    threaded.push([id]);
});


msglist.insertAdjacentHTML("beforeend", `<div class="accordion" id="accordionExample"></div>`);


threaded.reverse().forEach((messages, id) => {
  let text = messages_by_id[messages[0]].querySelector('.msg-content').textContent;

  document.querySelector('#accordionExample').insertAdjacentHTML('beforeend', `
  <div class="card">
    <div class="card-header" id="accordionheading${id}">
      <h2 class="mb-0">
        <button class="btn btn-link btn-block text-left" type="button" data-toggle="collapse" data-target="#accordioncollapse${id}" aria-expanded="true" aria-controls="accordioncollapse${id}" title="${text.replace(/["\r\n<>]/, ' ')}">
          <span class="badge badge-warning">${(messages.length - 1) + ' válasz'}</span>
          ${text.substring(0, 70) + '...'}
        </button>
      </h2>
    </div>

    <div id="accordioncollapse${id}" class="collapse" aria-labelledby="accordionheading${id}" data-parent="#accordionExample">
      <div class="card-body">
        <ul class="list-group">
        </ul>
      </div>
    </div>
  </div>
`);

  let list = document.querySelector('#accordioncollapse' + id + ' .card-body .list-group');

  messages.reverse().forEach(message => {
    list.insertAdjacentHTML('beforeend', '<li class="list-group-item"></li>');
    list.querySelector('.list-group-item:last-child').appendChild(messages_by_id[message]);
  });
});