(function () {
  const navLinks = document.querySelectorAll('.wiki-nav a[href^="#"]');
  const sections = Array.from(navLinks).map((link) => {
    const id = link.getAttribute('href').slice(1);
    return { link, el: document.getElementById(id) };
  }).filter((s) => s.el);

  function setActive(id) {
    navLinks.forEach((a) => {
      a.classList.toggle('active', a.getAttribute('href') === '#' + id);
    });
  }

  function scrollToTarget(id, el) {
    const target = el || document.getElementById(id);
    if (!target) return;
    target.scrollIntoView({ behavior: 'smooth', block: 'start' });
    history.replaceState(null, '', '#' + id);
    const section =
      target.closest('section') || (target.matches && target.matches('section') ? target : null);
    if (section) setActive(section.id);
  }

  navLinks.forEach((link) => {
    link.addEventListener('click', (e) => {
      e.preventDefault();
      const id = link.getAttribute('href').slice(1);
      scrollToTarget(id);
    });
  });

  if ('IntersectionObserver' in window && sections.length) {
    const observer = new IntersectionObserver(
      (entries) => {
        const visible = entries
          .filter((e) => e.isIntersecting)
          .sort((a, b) => b.intersectionRatio - a.intersectionRatio)[0];
        if (visible) setActive(visible.target.id);
      },
      { rootMargin: '-20% 0px -60% 0px', threshold: [0, 0.25, 0.5] }
    );
    sections.forEach((s) => observer.observe(s.el));
  }

  const hash = window.location.hash.slice(1);
  if (hash && document.getElementById(hash)) {
    setActive(hash);
    const section = document.getElementById(hash).closest('section');
    if (section) setActive(section.id);
  } else if (sections.length) {
    setActive(sections[0].el.id);
  }

  /* ── Search ── */
  const searchInput = document.getElementById('wiki-search-input');
  const searchResults = document.getElementById('wiki-search-results');
  const HIGHLIGHT_CLASS = 'wiki-search-highlight';
  let activeHighlights = [];

  function stripText(el) {
    return (el.textContent || '').replace(/\s+/g, ' ').trim();
  }

  function buildSearchIndex() {
    const entries = [];
    document.querySelectorAll('.wiki-content section').forEach((section) => {
      const sectionId = section.id;
      const sectionTitle = stripText(section.querySelector('h2') || section);

      section.querySelectorAll('h3, h4').forEach((heading) => {
        const headingId = heading.id || sectionId;
        entries.push({
          id: headingId,
          sectionId,
          title: stripText(heading),
          sectionTitle,
          text: stripText(heading),
          el: heading,
        });
      });

      section.querySelectorAll('p, li, td').forEach((block) => {
        const text = stripText(block);
        if (text.length < 12) return;
        entries.push({
          id: sectionId,
          sectionId,
          title: sectionTitle,
          sectionTitle,
          text,
          el: block,
        });
      });
    });
    return entries;
  }

  const searchIndex = buildSearchIndex();

  function clearHighlights() {
    activeHighlights.forEach((mark) => {
      const parent = mark.parentNode;
      if (!parent) return;
      parent.replaceChild(document.createTextNode(mark.textContent), mark);
      parent.normalize();
    });
    activeHighlights = [];
  }

  function escapeRegExp(s) {
    return s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
  }

  function highlightMatches(el, query) {
    clearHighlights();
    if (!el || !query) return;
    const terms = query.toLowerCase().split(/\s+/).filter((t) => t.length > 1);
    if (!terms.length) return;

    const walker = document.createTreeWalker(el, NodeFilter.SHOW_TEXT);
    const textNodes = [];
    while (walker.nextNode()) textNodes.push(walker.currentNode);

    const pattern = new RegExp('(' + terms.map(escapeRegExp).join('|') + ')', 'gi');

    textNodes.forEach((node) => {
      const val = node.nodeValue;
      if (!val || !pattern.test(val)) return;
      pattern.lastIndex = 0;
      const frag = document.createDocumentFragment();
      let last = 0;
      val.replace(pattern, (match, _g, offset) => {
        if (offset > last) {
          frag.appendChild(document.createTextNode(val.slice(last, offset)));
        }
        const mark = document.createElement('mark');
        mark.className = HIGHLIGHT_CLASS;
        mark.textContent = match;
        frag.appendChild(mark);
        activeHighlights.push(mark);
        last = offset + match.length;
        return match;
      });
      if (last < val.length) {
        frag.appendChild(document.createTextNode(val.slice(last)));
      }
      node.parentNode.replaceChild(frag, node);
    });
  }

  function scoreEntry(entry, terms) {
    const title = entry.title.toLowerCase();
    const text = entry.text.toLowerCase();
    let score = 0;
    terms.forEach((term) => {
      if (title.includes(term)) score += 10;
      if (text.includes(term)) score += 3;
      if (title.startsWith(term)) score += 5;
    });
    return score;
  }

  function snippet(text, terms, maxLen) {
    const lower = text.toLowerCase();
    let idx = -1;
    for (const term of terms) {
      const i = lower.indexOf(term);
      if (i !== -1 && (idx === -1 || i < idx)) idx = i;
    }
    if (idx === -1) return text.slice(0, maxLen) + (text.length > maxLen ? '…' : '');
    const start = Math.max(0, idx - 30);
    const slice = text.slice(start, start + maxLen);
    return (start > 0 ? '…' : '') + slice + (start + maxLen < text.length ? '…' : '');
  }

  function renderSearchResults(query) {
    if (!searchResults) return;
    const terms = query.toLowerCase().split(/\s+/).filter((t) => t.length > 1);
    searchResults.innerHTML = '';

    if (!terms.length) {
      searchResults.hidden = true;
      clearHighlights();
      return;
    }

    const hits = searchIndex
      .map((entry) => ({ entry, score: scoreEntry(entry, terms) }))
      .filter((h) => h.score > 0)
      .sort((a, b) => b.score - a.score)
      .slice(0, 12);

    if (!hits.length) {
      const li = document.createElement('li');
      li.className = 'wiki-search-empty';
      li.textContent = 'No matches';
      searchResults.appendChild(li);
      searchResults.hidden = false;
      return;
    }

    hits.forEach(({ entry }) => {
      const li = document.createElement('li');
      const btn = document.createElement('button');
      btn.type = 'button';
      btn.className = 'wiki-search-hit';
      const title = document.createElement('span');
      title.className = 'wiki-search-hit-title';
      title.textContent = entry.title;
      const preview = document.createElement('span');
      preview.className = 'wiki-search-hit-preview';
      preview.textContent = snippet(entry.text, terms, 80);
      btn.appendChild(title);
      btn.appendChild(preview);
      btn.addEventListener('click', () => {
        clearHighlights();
        const scrollEl = entry.el.id ? entry.el : document.getElementById(entry.id);
        scrollToTarget(entry.id, scrollEl);
        const highlightRoot = entry.el.closest('section') || entry.el;
        highlightMatches(highlightRoot, query);
        searchResults.hidden = true;
        searchInput.blur();
      });
      li.appendChild(btn);
      searchResults.appendChild(li);
    });
    searchResults.hidden = false;
  }

  if (searchInput && searchResults) {
    let debounceTimer;
    searchInput.addEventListener('input', () => {
      clearTimeout(debounceTimer);
      debounceTimer = setTimeout(() => renderSearchResults(searchInput.value.trim()), 120);
    });
    searchInput.addEventListener('keydown', (e) => {
      if (e.key === 'Escape') {
        searchInput.value = '';
        searchResults.hidden = true;
        clearHighlights();
      }
    });
    document.addEventListener('click', (e) => {
      if (!e.target.closest('.wiki-search')) {
        searchResults.hidden = true;
      }
    });
  }
})();