(function () {
  const input = document.getElementById("knowledge-search");
  const count = document.getElementById("knowledge-count");
  const entries = Array.from(document.querySelectorAll("[data-knowledge-entry]"));

  if (input instanceof HTMLInputElement && count) {
    function update() {
      const query = input.value.trim().toLowerCase();
      let visible = 0;

      for (const entry of entries) {
        const matches = !query || (entry.getAttribute("data-search") || "").includes(query);
        entry.hidden = !matches;
        if (matches) visible += 1;
      }

      const noResults = document.getElementById("knowledge-no-results");
      if (noResults) noResults.hidden = visible > 0;

      count.textContent = query
        ? `${visible} of ${entries.length} pages`
        : `${entries.length} pages`;
    }

    input.addEventListener("input", update);
  }

  const preview = document.getElementById("knowledge-preview");
  const previewTitle = document.getElementById("knowledge-preview-title");
  const previewMeta = document.getElementById("knowledge-preview-meta");
  const previewSummary = document.getElementById("knowledge-preview-summary");
  const previewExcerpt = document.getElementById("knowledge-preview-excerpt");
  const previewSources = Array.from(document.querySelectorAll("[data-knowledge-preview-source]"));

  if (
    preview &&
    previewTitle &&
    previewMeta &&
    previewSummary &&
    previewExcerpt &&
    previewSources.length > 0
  ) {
    const normalizePath = (path) => path.length > 1 ? path.replace(/\/$/, "") : path;
    const sourceByPath = new Map(previewSources.map((source) => [
      normalizePath(source.getAttribute("data-preview-href") || ""),
      source,
    ]));
    let activeLink;

    function sourceForTarget(target) {
      if (!(target instanceof Element)) return;
      const link = target.closest("a[href]");
      if (!(link instanceof HTMLAnchorElement)) return;

      const url = new URL(link.href, window.location.href);
      if (url.origin !== window.location.origin) return;
      const source = sourceByPath.get(normalizePath(url.pathname));
      return source ? { link, source } : undefined;
    }

    function showPreview(link, source) {
      if (activeLink === link) return;
      activeLink = link;
      previewTitle.textContent = source.getAttribute("data-preview-title") || "";
      previewMeta.textContent = source.getAttribute("data-preview-meta") || "";
      previewSummary.textContent = source.getAttribute("data-preview-summary") || "";
      previewExcerpt.textContent = source.getAttribute("data-preview-excerpt") || "";
      preview.setAttribute("data-active", "");
      preview.setAttribute("aria-hidden", "false");
    }

    function hidePreview(link) {
      if (link && activeLink !== link) return;
      activeLink = undefined;
      preview.removeAttribute("data-active");
      preview.setAttribute("aria-hidden", "true");
    }

    document.addEventListener("pointerover", (event) => {
      const target = sourceForTarget(event.target);
      if (target) showPreview(target.link, target.source);
    });

    document.addEventListener("pointerout", (event) => {
      const target = sourceForTarget(event.target);
      if (!target) return;
      if (event.relatedTarget instanceof Node && target.link.contains(event.relatedTarget)) return;
      hidePreview(target.link);
    });

    document.addEventListener("focusin", (event) => {
      const target = sourceForTarget(event.target);
      if (target) showPreview(target.link, target.source);
    });

    document.addEventListener("focusout", (event) => {
      const target = sourceForTarget(event.target);
      if (target) hidePreview(target.link);
    });
  }

  const contents = document.getElementById("knowledge-contents");
  const contentsList = document.getElementById("knowledge-contents-list");
  const knowledgeMain = document.querySelector(".knowledge-overview, .knowledge-entry");

  if (contents && contentsList && knowledgeMain) {
    const headings = Array.from(knowledgeMain.querySelectorAll("h1, h2, h3"))
      .filter((heading) => heading.textContent && !heading.closest(".knowledge-chart"));
    const usedIds = new Set(Array.from(document.querySelectorAll("[id]"))
      .map((element) => element.id)
      .filter(Boolean));

    function headingId(heading, index) {
      if (heading.id) return heading.id;
      const base = (heading.textContent || "section")
        .toLowerCase()
        .normalize("NFKD")
        .replace(/[\u0300-\u036f]/g, "")
        .replace(/[^a-z0-9]+/g, "-")
        .replace(/^-|-$/g, "") || `section-${index + 1}`;
      let id = base;
      let suffix = 2;
      while (usedIds.has(id)) id = `${base}-${suffix++}`;
      heading.id = id;
      usedIds.add(id);
      return id;
    }

    const links = headings.map((heading, index) => {
      const item = document.createElement("li");
      const link = document.createElement("a");
      const id = headingId(heading, index);
      item.dataset.level = heading.tagName.slice(1);
      link.href = `#${id}`;
      link.textContent = heading.textContent.trim();
      item.append(link);
      contentsList.append(item);
      return { heading, link };
    });

    for (const link of document.querySelectorAll("[data-knowledge-heading-link]")) {
      const id = (link.getAttribute("href") || "").slice(1);
      if (document.getElementById(id)) link.hidden = false;
    }

    if (links.length > 1) {
      contents.setAttribute("data-active", "");
      contents.setAttribute("aria-hidden", "false");

      if (window.location.hash.length > 1) {
        const initialTarget = document.getElementById(decodeURIComponent(window.location.hash.slice(1)));
        if (initialTarget) window.requestAnimationFrame(() => initialTarget.scrollIntoView());
      }

      let frame;
      const updateCurrent = () => {
        frame = undefined;
        const threshold = window.innerHeight * 0.24;
        let current = links[0];
        for (const candidate of links) {
          if (candidate.heading.getBoundingClientRect().top <= threshold) current = candidate;
          else break;
        }
        for (const candidate of links) {
          const active = candidate === current;
          candidate.link.toggleAttribute("data-current", active);
          if (active) candidate.link.setAttribute("aria-current", "location");
          else candidate.link.removeAttribute("aria-current");
        }
      };
      const requestUpdate = () => {
        if (frame) return;
        frame = window.requestAnimationFrame(updateCurrent);
      };
      window.addEventListener("scroll", requestUpdate, { passive: true });
      window.addEventListener("resize", requestUpdate);
      updateCurrent();
    }
  }
})();