/* OPENBUREAU — Versionsverlauf eines Beitrags direkt auf der Seite.
   Die Marke „Version xxx" neben dem Kopf öffnet die Liste der Fassungen
   (aus /api/history); Auswahl ersetzt den Beitragstext mit der alten Fassung
   (aus /api/history/version) und zeigt einen Banner mit Rücksprung. */
(function () {
  var badge = document.getElementById('version-badge');
  if (!badge) return;
  var path = badge.dataset.path;
  var content = document.querySelector('.single-content');
  var article = document.querySelector('article.single');
  if (!path || !content || !article) return;

  var originalHTML = content.innerHTML;
  var originalLabel = badge.textContent;
  var panel = null, banner = null;

  function api(p) {
    return fetch(p).then(function (r) { return r.ok ? r.json() : null; }).catch(function () { return null; });
  }
  function fmt(d) { try { return new Date(d).toLocaleDateString('de-CH'); } catch (e) { return d || ''; } }

  function closePanel() {
    if (panel) { panel.remove(); panel = null; }
    badge.setAttribute('aria-expanded', 'false');
  }
  function restore() {
    content.innerHTML = originalHTML;
    badge.textContent = originalLabel;
    if (banner) { banner.remove(); banner = null; }
  }
  function showBanner(v) {
    if (banner) banner.remove();
    banner = document.createElement('div');
    banner.className = 'version-banner';
    banner.append('Ältere Fassung vom ' + fmt(v.date) + ' · Version ' + v.short + '  ');
    var back = document.createElement('button');
    back.type = 'button'; back.className = 'version-back'; back.textContent = '→ Zur aktuellen Fassung';
    back.addEventListener('click', restore);
    banner.appendChild(back);
    article.insertBefore(banner, article.firstChild);
  }
  function loadVersion(v) {
    closePanel();
    content.innerHTML = '<p class="version-loading">Lade Fassung …</p>';
    api('/api/history/version?path=' + encodeURIComponent(path) + '&rev=' + encodeURIComponent(v.rev)).then(function (data) {
      if (!data || !data.html) { restore(); return; }
      content.innerHTML = data.html;
      badge.textContent = 'Version ' + v.short;
      showBanner(v);
      window.scrollTo({ top: 0, behavior: 'smooth' });
    });
  }
  function openPanel() {
    api('/api/history?path=' + encodeURIComponent(path)).then(function (list) {
      panel = document.createElement('div');
      panel.className = 'version-panel';
      if (!list || !list.length) {
        panel.innerHTML = '<p class="version-empty">Kein Verlauf verfügbar.</p>';
      } else {
        var ol = document.createElement('ol');
        ol.className = 'version-list';
        list.forEach(function (v, i) {
          var li = document.createElement('li');
          var b = document.createElement('button');
          b.type = 'button';
          var date = document.createElement('span'); date.className = 'v-date'; date.textContent = fmt(v.date);
          var subj = document.createElement('span'); subj.className = 'v-subject'; subj.textContent = v.subject || '';
          var hash = document.createElement('span'); hash.className = 'v-hash'; hash.textContent = v.short + (i === 0 ? ' · aktuell' : '');
          b.append(date, subj, hash);
          if (i === 0) b.addEventListener('click', function () { restore(); closePanel(); });
          else b.addEventListener('click', function () { loadVersion(v); });
          li.appendChild(b);
          ol.appendChild(li);
        });
        panel.appendChild(ol);
      }
      badge.parentNode.insertBefore(panel, badge.nextSibling);
      badge.setAttribute('aria-expanded', 'true');
    });
  }

  badge.addEventListener('click', function () { panel ? closePanel() : openPanel(); });
})();