4 files changed, 1196 insertions, 0 deletions
diff --git a/services/nuldoc/nuldoc-src/markdown/document.ts b/services/nuldoc/nuldoc-src/markdown/document.ts
new file mode 100644
index 0000000..1aee87b
--- /dev/null
+++ b/services/nuldoc/nuldoc-src/markdown/document.ts
@@ -0,0 +1,75 @@
+import type { Root as MdastRoot } from "mdast";
+import { join } from "@std/path";
+import { z } from "zod/mod.ts";
+import { Config } from "../config.ts";
+import { Element } from "../dom.ts";
+import { Revision, stringToDate } from "../revision.ts";
+import { mdast2ndoc } from "./mdast2ndoc.ts";
+
+export const PostMetadataSchema = z.object({
+  article: z.object({
+    uuid: z.string(),
+    title: z.string(),
+    description: z.string(),
+    tags: z.array(z.string()),
+    toc: z.boolean().optional(),
+    revisions: z.array(z.object({
+      date: z.string(),
+      remark: z.string(),
+      isInternal: z.boolean().optional(),
+    })),
+  }),
+});
+
+export type PostMetadata = z.infer<typeof PostMetadataSchema>;
+
+export type TocEntry = {
+  id: string;
+  text: string;
+  level: number;
+  children: TocEntry[];
+};
+
+export type TocRoot = {
+  entries: TocEntry[];
+};
+
+export type Document = {
+  root: Element;
+  sourceFilePath: string;
+  uuid: string;
+  link: string;
+  title: string;
+  description: string;
+  tags: string[];
+  revisions: Revision[];
+  toc?: TocRoot;
+  isTocEnabled: boolean;
+};
+
+export function createNewDocumentFromMdast(
+  root: MdastRoot,
+  meta: PostMetadata,
+  sourceFilePath: string,
+  config: Config,
+): Document {
+  const cwd = Deno.cwd();
+  const contentDir = join(cwd, config.locations.contentDir);
+  const link = sourceFilePath.replace(contentDir, "").replace(".xml", "/");
+  return {
+    root: mdast2ndoc(root),
+    sourceFilePath,
+    uuid: meta.article.uuid,
+    link: link,
+    title: meta.article.title,
+    description: meta.article.description,
+    tags: meta.article.tags,
+    revisions: meta.article.revisions.map((r, i) => ({
+      number: i,
+      date: stringToDate(r.date),
+      remark: r.remark,
+      isInternal: !!r.isInternal,
+    })),
+    isTocEnabled: meta.article.toc !== false,
+  };
+}
diff --git a/services/nuldoc/nuldoc-src/markdown/mdast2ndoc.ts b/services/nuldoc/nuldoc-src/markdown/mdast2ndoc.ts
new file mode 100644
index 0000000..367627c
--- /dev/null
+++ b/services/nuldoc/nuldoc-src/markdown/mdast2ndoc.ts
@@ -0,0 +1,575 @@
+import type {
+  Blockquote,
+  Code,
+  Definition,
+  Delete,
+  Emphasis,
+  FootnoteDefinition,
+  FootnoteReference,
+  Heading,
+  Html,
+  Image,
+  InlineCode,
+  Link,
+  List,
+  ListItem,
+  Paragraph,
+  PhrasingContent,
+  Root,
+  RootContent,
+  Strong,
+  Table,
+  TableCell,
+  TableRow,
+  Text as MdastText,
+  ThematicBreak,
+} from "mdast";
+import type {
+  ContainerDirective,
+  LeafDirective,
+  TextDirective,
+} from "mdast-util-directive";
+import { elem, Element, Node, rawHTML, text } from "../dom.ts";
+
+type DirectiveNode = ContainerDirective | LeafDirective | TextDirective;
+
+function isDirective(node: RootContent): node is DirectiveNode {
+  return (
+    node.type === "containerDirective" ||
+    node.type === "leafDirective" ||
+    node.type === "textDirective"
+  );
+}
+
+// Extract section ID and attributes from heading if present
+// Supports syntax like {#id} or {#id attr="value"}
+function extractSectionId(
+  node: Heading,
+): {
+  id: string | null;
+  attributes: Record<string, string>;
+  children: Heading["children"];
+} {
+  if (node.children.length === 0) {
+    return { id: null, attributes: {}, children: node.children };
+  }
+
+  const lastChild = node.children[node.children.length - 1];
+  if (lastChild && lastChild.type === "text") {
+    // Match {#id ...} or {#id attr="value" ...}
+    const match = lastChild.value.match(/\s*\{#([^\s}]+)([^}]*)\}\s*$/);
+    if (match) {
+      const id = match[1];
+      const attrString = match[2].trim();
+      const attributes: Record<string, string> = {};
+
+      // Parse attributes like toc="false" (supports smart quotes too)
+      // U+0022 = ", U+201C = ", U+201D = "
+      const attrRegex =
+        /(\w+)=["\u201c\u201d]([^"\u201c\u201d]*)["\u201c\u201d]/g;
+      let attrMatch;
+      while ((attrMatch = attrRegex.exec(attrString)) !== null) {
+        attributes[attrMatch[1]] = attrMatch[2];
+      }
+
+      const newValue = lastChild.value.replace(/\s*\{#[^}]+\}\s*$/, "");
+      if (newValue === "") {
+        return { id, attributes, children: node.children.slice(0, -1) };
+      } else {
+        const newChildren = [...node.children];
+        newChildren[newChildren.length - 1] = { ...lastChild, value: newValue };
+        return { id, attributes, children: newChildren };
+      }
+    }
+  }
+
+  return { id: null, attributes: {}, children: node.children };
+}
+
+function processBlock(node: RootContent): Element | Element[] | null {
+  switch (node.type) {
+    case "heading":
+      // Headings are handled specially in mdast2ndoc
+      return null;
+    case "paragraph":
+      return processParagraph(node);
+    case "thematicBreak":
+      return processThematicBreak(node);
+    case "blockquote":
+      return processBlockquote(node);
+    case "code":
+      return processCode(node);
+    case "list":
+      return processList(node);
+    case "table":
+      return processTable(node);
+    case "html":
+      return processHtmlBlock(node);
+    case "definition":
+      return processDefinition(node);
+    case "footnoteDefinition":
+      return processFootnoteDefinition(node);
+    default:
+      if (isDirective(node)) {
+        return processDirective(node);
+      }
+      return null;
+  }
+}
+
+function processParagraph(node: Paragraph): Element {
+  return elem("p", {}, ...node.children.map(processInline));
+}
+
+function processThematicBreak(_node: ThematicBreak): Element {
+  return elem("hr", {});
+}
+
+function processBlockquote(node: Blockquote): Element {
+  const children: Node[] = [];
+  for (const child of node.children) {
+    const result = processBlock(child);
+    if (result) {
+      if (Array.isArray(result)) {
+        children.push(...result);
+      } else {
+        children.push(result);
+      }
+    }
+  }
+  return elem("blockquote", {}, ...children);
+}
+
+function processCode(node: Code): Element {
+  const attributes: Record<string, string> = {};
+
+  if (node.lang) {
+    attributes.language = node.lang;
+  }
+
+  // Parse meta string for filename and numbered attributes
+  if (node.meta) {
+    const filenameMatch = node.meta.match(/filename="([^"]+)"/);
+    if (filenameMatch) {
+      attributes.filename = filenameMatch[1];
+    }
+
+    if (node.meta.includes("numbered")) {
+      attributes.numbered = "true";
+    }
+  }
+
+  return elem("codeblock", attributes, text(node.value));
+}
+
+function processList(node: List): Element {
+  const attributes: Record<string, string> = {};
+  attributes.__tight = node.spread === false ? "true" : "false";
+
+  const isTaskList = node.children.some(
+    (item) => item.checked !== null && item.checked !== undefined,
+  );
+
+  if (isTaskList) {
+    attributes.type = "task";
+  }
+
+  if (node.ordered && node.start !== null && node.start !== 1) {
+    attributes.start = node.start!.toString();
+  }
+
+  const children = node.children.map((item) =>
+    processListItem(item, isTaskList)
+  );
+
+  return elem(node.ordered ? "ol" : "ul", attributes, ...children);
+}
+
+function processListItem(node: ListItem, isTaskList: boolean): Element {
+  const attributes: Record<string, string> = {};
+
+  if (isTaskList) {
+    attributes.checked = node.checked ? "true" : "false";
+  }
+
+  const children: Node[] = [];
+  for (const child of node.children) {
+    const result = processBlock(child);
+    if (result) {
+      if (Array.isArray(result)) {
+        children.push(...result);
+      } else {
+        children.push(result);
+      }
+    }
+  }
+
+  return elem("li", attributes, ...children);
+}
+
+function processTable(node: Table): Element {
+  const tableElement = elem("table", {});
+  const headerRows: Element[] = [];
+  const bodyRows: Element[] = [];
+
+  node.children.forEach((row, rowIndex) => {
+    const rowElement = processTableRow(row, rowIndex === 0, node.align);
+    if (rowIndex === 0) {
+      headerRows.push(rowElement);
+    } else {
+      bodyRows.push(rowElement);
+    }
+  });
+
+  if (headerRows.length > 0) {
+    tableElement.children.push(elem("thead", undefined, ...headerRows));
+  }
+
+  if (bodyRows.length > 0) {
+    tableElement.children.push(elem("tbody", undefined, ...bodyRows));
+  }
+
+  return tableElement;
+}
+
+function processTableRow(
+  node: TableRow,
+  isHeader: boolean,
+  alignments: (string | null)[] | null | undefined,
+): Element {
+  const cells = node.children.map((cell, index) =>
+    processTableCell(cell, isHeader, alignments?.[index])
+  );
+  return elem("tr", {}, ...cells);
+}
+
+function processTableCell(
+  node: TableCell,
+  isHeader: boolean,
+  alignment: string | null | undefined,
+): Element {
+  const attributes: Record<string, string> = {};
+  if (alignment && alignment !== "none") {
+    attributes.align = alignment;
+  }
+
+  return elem(
+    isHeader ? "th" : "td",
+    attributes,
+    ...node.children.map(processInline),
+  );
+}
+
+function processHtmlBlock(node: Html): Element {
+  return elem("div", { class: "raw-html" }, rawHTML(node.value));
+}
+
+function processDefinition(_node: Definition): null {
+  // Link definitions are handled elsewhere
+  return null;
+}
+
+function processFootnoteDefinition(node: FootnoteDefinition): Element {
+  const children: Node[] = [];
+  for (const child of node.children) {
+    const result = processBlock(child);
+    if (result) {
+      if (Array.isArray(result)) {
+        children.push(...result);
+      } else {
+        children.push(result);
+      }
+    }
+  }
+  return elem("footnote", { id: node.identifier }, ...children);
+}
+
+function processDirective(node: DirectiveNode): Element | null {
+  const name = node.name;
+
+  if (name === "note" || name === "edit") {
+    const attributes: Record<string, string> = {};
+
+    // Copy directive attributes
+    if (node.attributes) {
+      for (const [key, value] of Object.entries(node.attributes)) {
+        if (value !== undefined && value !== null) {
+          attributes[key] = String(value);
+        }
+      }
+    }
+
+    const children: Node[] = [];
+    if ("children" in node && node.children) {
+      for (const child of node.children as RootContent[]) {
+        const result = processBlock(child);
+        if (result) {
+          if (Array.isArray(result)) {
+            children.push(...result);
+          } else {
+            children.push(result);
+          }
+        }
+      }
+    }
+
+    return elem("note", attributes, ...children);
+  }
+
+  // For other directives, treat as div
+  const children: Node[] = [];
+  if ("children" in node && node.children) {
+    for (const child of node.children as RootContent[]) {
+      const result = processBlock(child);
+      if (result) {
+        if (Array.isArray(result)) {
+          children.push(...result);
+        } else {
+          children.push(result);
+        }
+      }
+    }
+  }
+
+  return elem(
+    "div",
+    node.attributes as Record<string, string> || {},
+    ...children,
+  );
+}
+
+function processInline(node: PhrasingContent): Node {
+  switch (node.type) {
+    case "text":
+      return processText(node);
+    case "emphasis":
+      return processEmphasis(node);
+    case "strong":
+      return processStrong(node);
+    case "inlineCode":
+      return processInlineCode(node);
+    case "link":
+      return processLink(node);
+    case "image":
+      return processImage(node);
+    case "delete":
+      return processDelete(node);
+    case "break":
+      return elem("br");
+    case "html":
+      return rawHTML(node.value);
+    case "footnoteReference":
+      return processFootnoteReference(node);
+    default:
+      // Handle any unexpected node types
+      if ("value" in node) {
+        return text(String(node.value));
+      }
+      if ("children" in node && Array.isArray(node.children)) {
+        return elem(
+          "span",
+          {},
+          ...node.children.map((c: PhrasingContent) => processInline(c)),
+        );
+      }
+      return text("");
+  }
+}
+
+function processText(node: MdastText): Node {
+  return text(node.value);
+}
+
+function processEmphasis(node: Emphasis): Element {
+  return elem("em", {}, ...node.children.map(processInline));
+}
+
+function processStrong(node: Strong): Element {
+  return elem("strong", {}, ...node.children.map(processInline));
+}
+
+function processInlineCode(node: InlineCode): Element {
+  return elem("code", {}, text(node.value));
+}
+
+function processLink(node: Link): Element {
+  const attributes: Record<string, string> = {};
+  if (node.url) {
+    attributes.href = node.url;
+  }
+  if (node.title) {
+    attributes.title = node.title;
+  }
+  // Detect autolinks (URL equals link text)
+  const isAutolink = node.children.length === 1 &&
+    node.children[0].type === "text" &&
+    node.children[0].value === node.url;
+  if (isAutolink) {
+    attributes.class = "url";
+  }
+  return elem("a", attributes, ...node.children.map(processInline));
+}
+
+function processImage(node: Image): Element {
+  const attributes: Record<string, string> = {};
+  if (node.url) {
+    attributes.src = node.url;
+  }
+  if (node.alt) {
+    attributes.alt = node.alt;
+  }
+  if (node.title) {
+    attributes.title = node.title;
+  }
+  return elem("img", attributes);
+}
+
+function processDelete(node: Delete): Element {
+  return elem("del", {}, ...node.children.map(processInline));
+}
+
+function processFootnoteReference(node: FootnoteReference): Element {
+  return elem("footnoteref", { reference: node.identifier });
+}
+
+// Build hierarchical section structure from flat mdast
+// This mimics Djot's section structure where headings create nested sections
+export function mdast2ndoc(root: Root): Element {
+  const footnotes: Element[] = [];
+  const nonFootnoteChildren: RootContent[] = [];
+
+  // Separate footnotes from other content
+  for (const child of root.children) {
+    if (child.type === "footnoteDefinition") {
+      const footnote = processFootnoteDefinition(child);
+      footnotes.push(footnote);
+    } else {
+      nonFootnoteChildren.push(child);
+    }
+  }
+
+  // Build hierarchical sections
+  const articleContent = buildSectionHierarchy(nonFootnoteChildren);
+
+  // Add footnotes section if any exist
+  if (footnotes.length > 0) {
+    const footnoteSection = elem(
+      "section",
+      { class: "footnotes" },
+      ...footnotes,
+    );
+    articleContent.push(footnoteSection);
+  }
+
+  return elem(
+    "__root__",
+    undefined,
+    elem("article", undefined, ...articleContent),
+  );
+}
+
+type SectionInfo = {
+  id: string | null;
+  attributes: Record<string, string>;
+  level: number;
+  heading: Element;
+  children: Node[];
+};
+
+function buildSectionHierarchy(nodes: RootContent[]): Node[] {
+  // Group nodes into sections based on headings
+  // Each heading starts a new section at its level
+  const result: Node[] = [];
+  const sectionStack: SectionInfo[] = [];
+
+  for (const node of nodes) {
+    if (node.type === "heading") {
+      const level = node.depth;
+      const { id, attributes, children } = extractSectionId(node);
+
+      // Create heading element
+      const headingElement = elem(
+        "h",
+        {},
+        ...children.map(processInline),
+      );
+
+      // Close sections that are at same or deeper level
+      while (
+        sectionStack.length > 0 &&
+        sectionStack[sectionStack.length - 1].level >= level
+      ) {
+        const closedSection = sectionStack.pop()!;
+        const sectionElement = createSectionElement(closedSection);
+
+        if (sectionStack.length > 0) {
+          // Add to parent section
+          sectionStack[sectionStack.length - 1].children.push(sectionElement);
+        } else {
+          // Add to result
+          result.push(sectionElement);
+        }
+      }
+
+      // Start new section
+      const newSection: SectionInfo = {
+        id,
+        attributes,
+        level,
+        heading: headingElement,
+        children: [],
+      };
+      sectionStack.push(newSection);
+    } else {
+      // Non-heading content
+      const processed = processBlock(node);
+      if (processed) {
+        if (sectionStack.length > 0) {
+          // Add to current section
+          if (Array.isArray(processed)) {
+            sectionStack[sectionStack.length - 1].children.push(...processed);
+          } else {
+            sectionStack[sectionStack.length - 1].children.push(processed);
+          }
+        } else {
+          // Content before any heading
+          if (Array.isArray(processed)) {
+            result.push(...processed);
+          } else {
+            result.push(processed);
+          }
+        }
+      }
+    }
+  }
+
+  // Close remaining sections
+  while (sectionStack.length > 0) {
+    const closedSection = sectionStack.pop()!;
+    const sectionElement = createSectionElement(closedSection);
+
+    if (sectionStack.length > 0) {
+      // Add to parent section
+      sectionStack[sectionStack.length - 1].children.push(sectionElement);
+    } else {
+      // Add to result
+      result.push(sectionElement);
+    }
+  }
+
+  return result;
+}
+
+function createSectionElement(sectionInfo: SectionInfo): Element {
+  const attributes: Record<string, string> = { ...sectionInfo.attributes };
+  if (sectionInfo.id) {
+    attributes.id = sectionInfo.id;
+  }
+
+  return elem(
+    "section",
+    attributes,
+    sectionInfo.heading,
+    ...sectionInfo.children,
+  );
+}
diff --git a/services/nuldoc/nuldoc-src/markdown/parse.ts b/services/nuldoc/nuldoc-src/markdown/parse.ts
new file mode 100644
index 0000000..c0875a2
--- /dev/null
+++ b/services/nuldoc/nuldoc-src/markdown/parse.ts
@@ -0,0 +1,47 @@
+import type { Root as MdastRoot } from "mdast";
+import { unified } from "unified";
+import remarkParse from "remark-parse";
+import remarkGfm from "remark-gfm";
+import remarkDirective from "remark-directive";
+import remarkSmartypants from "remark-smartypants";
+import { parse as parseToml } from "@std/toml";
+import { Config } from "../config.ts";
+import {
+  createNewDocumentFromMdast,
+  Document,
+  PostMetadata,
+  PostMetadataSchema,
+} from "./document.ts";
+import toHtml from "./to_html.ts";
+
+export async function parseMarkdownFile(
+  filePath: string,
+  config: Config,
+): Promise<Document> {
+  try {
+    const fileContent = await Deno.readTextFile(filePath);
+    const [, frontmatter, ...rest] = fileContent.split(/^---$/m);
+    const meta = parseMetadata(frontmatter);
+    const content = rest.join("---");
+
+    const processor = unified()
+      .use(remarkParse)
+      .use(remarkGfm)
+      .use(remarkDirective)
+      .use(remarkSmartypants);
+
+    const root = await processor.run(processor.parse(content)) as MdastRoot;
+
+    const doc = createNewDocumentFromMdast(root, meta, filePath, config);
+    return await toHtml(doc);
+  } catch (e) {
+    if (e instanceof Error) {
+      e.message = `${e.message} in ${filePath}`;
+    }
+    throw e;
+  }
+}
+
+function parseMetadata(s: string): PostMetadata {
+  return PostMetadataSchema.parse(parseToml(s));
+}
diff --git a/services/nuldoc/nuldoc-src/markdown/to_html.ts b/services/nuldoc/nuldoc-src/markdown/to_html.ts
new file mode 100644
index 0000000..8219b74
--- /dev/null
+++ b/services/nuldoc/nuldoc-src/markdown/to_html.ts
@@ -0,0 +1,499 @@
+import { BundledLanguage, bundledLanguages, codeToHtml } from "shiki";
+import { Document, TocEntry } from "./document.ts";
+import { NuldocError } from "../errors.ts";
+import {
+  addClass,
+  elem,
+  Element,
+  forEachChild,
+  forEachChildRecursively,
+  forEachChildRecursivelyAsync,
+  forEachElementOfType,
+  innerText,
+  Node,
+  processTextNodesInElement,
+  RawHTML,
+  rawHTML,
+  Text,
+  text,
+} from "../dom.ts";
+
+export default async function toHtml(doc: Document): Promise<Document> {
+  mergeConsecutiveTextNodes(doc);
+  removeUnnecessaryTextNode(doc);
+  transformLinkLikeToAnchorElement(doc);
+  transformSectionIdAttribute(doc);
+  setSectionTitleAnchor(doc);
+  transformSectionTitleElement(doc);
+  transformNoteElement(doc);
+  addAttributesToExternalLinkElement(doc);
+  traverseFootnotes(doc);
+  removeUnnecessaryParagraphNode(doc);
+  await transformAndHighlightCodeBlockElement(doc);
+  mergeConsecutiveTextNodes(doc);
+  generateTableOfContents(doc);
+  removeTocAttributes(doc);
+  return doc;
+}
+
+function mergeConsecutiveTextNodes(doc: Document) {
+  forEachChildRecursively(doc.root, (n) => {
+    if (n.kind !== "element") {
+      return;
+    }
+
+    const newChildren: Node[] = [];
+    let currentTextContent = "";
+
+    for (const child of n.children) {
+      if (child.kind === "text") {
+        currentTextContent += child.content;
+      } else {
+        if (currentTextContent !== "") {
+          newChildren.push(text(currentTextContent));
+          currentTextContent = "";
+        }
+        newChildren.push(child);
+      }
+    }
+
+    if (currentTextContent !== "") {
+      newChildren.push(text(currentTextContent));
+    }
+
+    n.children = newChildren;
+  });
+}
+
+function removeUnnecessaryTextNode(doc: Document) {
+  forEachChildRecursively(doc.root, (n) => {
+    if (n.kind !== "element") {
+      return;
+    }
+
+    let changed = true;
+    while (changed) {
+      changed = false;
+      if (n.children.length === 0) {
+        break;
+      }
+      const firstChild = n.children[0];
+      if (firstChild.kind === "text" && firstChild.content.trim() === "") {
+        n.children.shift();
+        changed = true;
+      }
+      if (n.children.length === 0) {
+        break;
+      }
+      const lastChild = n.children[n.children.length - 1];
+      if (lastChild.kind === "text" && lastChild.content.trim() === "") {
+        n.children.pop();
+        changed = true;
+      }
+    }
+  });
+}
+
+function transformLinkLikeToAnchorElement(doc: Document) {
+  forEachChildRecursively(doc.root, (n) => {
+    if (
+      n.kind !== "element" || n.name === "a" || n.name === "code" ||
+      n.name === "codeblock"
+    ) {
+      return;
+    }
+
+    processTextNodesInElement(n, (content) => {
+      const nodes: Node[] = [];
+      let restContent = content;
+      while (restContent !== "") {
+        const match = /^(.*?)(https?:\/\/[^ \n]+)(.*)$/s.exec(restContent);
+        if (!match) {
+          nodes.push(text(restContent));
+          restContent = "";
+          break;
+        }
+        const [_, prefix, url, suffix] = match;
+        nodes.push(text(prefix));
+        nodes.push(elem("a", { href: url, class: "url" }, text(url)));
+        restContent = suffix;
+      }
+      return nodes;
+    });
+  });
+}
+
+function transformSectionIdAttribute(doc: Document) {
+  const sectionStack: string[] = [];
+  const usedIds = new Set<string>();
+
+  const processNode = (n: Node) => {
+    if (n.kind !== "element") {
+      return;
+    }
+
+    if (n.name === "section") {
+      const idAttr = n.attributes.id;
+      if (!idAttr) {
+        return;
+      }
+
+      let newId: string;
+      if (sectionStack.length === 0) {
+        newId = `section--${idAttr}`;
+      } else {
+        newId = `section--${sectionStack.join("--")}--${idAttr}`;
+      }
+
+      if (usedIds.has(newId)) {
+        throw new NuldocError(
+          `[nuldoc.tohtml] Duplicate section ID: ${newId}`,
+        );
+      }
+
+      usedIds.add(newId);
+      n.attributes.id = newId;
+      sectionStack.push(idAttr);
+
+      forEachChild(n, processNode);
+
+      sectionStack.pop();
+    } else {
+      forEachChild(n, processNode);
+    }
+  };
+
+  forEachChild(doc.root, processNode);
+}
+
+function setSectionTitleAnchor(doc: Document) {
+  const sectionStack: Element[] = [];
+  const g = (c: Node) => {
+    if (c.kind !== "element") {
+      return;
+    }
+
+    if (c.name === "section") {
+      sectionStack.push(c);
+    }
+    forEachChild(c, g);
+    if (c.name === "section") {
+      sectionStack.pop();
+    }
+    if (c.name === "h") {
+      const currentSection = sectionStack[sectionStack.length - 1];
+      if (!currentSection) {
+        throw new NuldocError(
+          "[nuldoc.tohtml] <h> element must be inside <section>",
+        );
+      }
+      const sectionId = currentSection.attributes.id;
+      const aElement = elem("a", undefined, ...c.children);
+      aElement.attributes.href = `#${sectionId}`;
+      c.children = [aElement];
+    }
+  };
+  forEachChild(doc.root, g);
+}
+
+function transformSectionTitleElement(doc: Document) {
+  let sectionLevel = 1;
+  const g = (c: Node) => {
+    if (c.kind !== "element") {
+      return;
+    }
+
+    if (c.name === "section") {
+      sectionLevel += 1;
+      c.attributes.__sectionLevel = sectionLevel.toString();
+    }
+    forEachChild(c, g);
+    if (c.name === "section") {
+      sectionLevel -= 1;
+    }
+    if (c.name === "h") {
+      c.name = `h${sectionLevel}`;
+    }
+  };
+  forEachChild(doc.root, g);
+}
+
+function transformNoteElement(doc: Document) {
+  forEachElementOfType(doc.root, "note", (n) => {
+    const editatAttr = n.attributes?.editat;
+    const operationAttr = n.attributes?.operation;
+    const isEditBlock = editatAttr && operationAttr;
+
+    const labelElement = elem(
+      "div",
+      { class: "admonition-label" },
+      text(isEditBlock ? `${editatAttr} ${operationAttr}` : "NOTE"),
+    );
+    const contentElement = elem(
+      "div",
+      { class: "admonition-content" },
+      ...n.children,
+    );
+    n.name = "div";
+    addClass(n, "admonition");
+    n.children = [labelElement, contentElement];
+  });
+}
+
+function addAttributesToExternalLinkElement(doc: Document) {
+  forEachElementOfType(doc.root, "a", (n) => {
+    const href = n.attributes.href ?? "";
+    if (!href.startsWith("http")) {
+      return;
+    }
+    n.attributes.target = "_blank";
+    n.attributes.rel = "noreferrer";
+  });
+}
+
+function traverseFootnotes(doc: Document) {
+  let footnoteCounter = 0;
+  const footnoteMap = new Map<string, number>();
+
+  forEachElementOfType(doc.root, "footnoteref", (n) => {
+    const reference = n.attributes.reference;
+    if (!reference) {
+      return;
+    }
+
+    let footnoteNumber: number;
+    if (footnoteMap.has(reference)) {
+      footnoteNumber = footnoteMap.get(reference)!;
+    } else {
+      footnoteNumber = ++footnoteCounter;
+      footnoteMap.set(reference, footnoteNumber);
+    }
+
+    n.name = "sup";
+    delete n.attributes.reference;
+    n.attributes.class = "footnote";
+    n.children = [
+      elem(
+        "a",
+        {
+          id: `footnoteref--${reference}`,
+          class: "footnote",
+          href: `#footnote--${reference}`,
+        },
+        text(`[${footnoteNumber}]`),
+      ),
+    ];
+  });
+
+  forEachElementOfType(doc.root, "footnote", (n) => {
+    const id = n.attributes.id;
+    if (!id || !footnoteMap.has(id)) {
+      n.name = "span";
+      n.children = [];
+      return;
+    }
+
+    const footnoteNumber = footnoteMap.get(id)!;
+
+    n.name = "div";
+    delete n.attributes.id;
+    n.attributes.class = "footnote";
+    n.attributes.id = `footnote--${id}`;
+
+    n.children = [
+      elem(
+        "a",
+        { href: `#footnoteref--${id}` },
+        text(`${footnoteNumber}. `),
+      ),
+      ...n.children,
+    ];
+  });
+}
+
+function removeUnnecessaryParagraphNode(doc: Document) {
+  forEachChildRecursively(doc.root, (n) => {
+    if (n.kind !== "element" || (n.name !== "ul" && n.name !== "ol")) {
+      return;
+    }
+
+    const isTight = n.attributes.__tight === "true";
+    if (!isTight) {
+      return;
+    }
+
+    for (const child of n.children) {
+      if (child.kind !== "element" || child.name !== "li") {
+        continue;
+      }
+      const newGrandChildren: Node[] = [];
+      for (const grandChild of child.children) {
+        if (grandChild.kind === "element" && grandChild.name === "p") {
+          newGrandChildren.push(...grandChild.children);
+        } else {
+          newGrandChildren.push(grandChild);
+        }
+      }
+      child.children = newGrandChildren;
+    }
+  });
+}
+
+async function transformAndHighlightCodeBlockElement(doc: Document) {
+  await forEachChildRecursivelyAsync(doc.root, async (n) => {
+    if (n.kind !== "element" || n.name !== "codeblock") {
+      return;
+    }
+
+    const language = n.attributes.language || "text";
+    const filename = n.attributes.filename;
+    const numbered = n.attributes.numbered;
+    const sourceCodeNode = n.children[0] as Text | RawHTML;
+    const sourceCode = sourceCodeNode.kind === "text"
+      ? sourceCodeNode.content.trimEnd()
+      : sourceCodeNode.html.trimEnd();
+
+    const highlighted = await codeToHtml(sourceCode, {
+      lang: language in bundledLanguages ? language as BundledLanguage : "text",
+      theme: "github-light",
+      colorReplacements: {
+        "#fff": "#f5f5f5",
+      },
+    });
+
+    n.name = "div";
+    n.attributes.class = "codeblock";
+    delete n.attributes.language;
+
+    if (numbered === "true") {
+      delete n.attributes.numbered;
+      addClass(n, "numbered");
+    }
+    if (filename) {
+      delete n.attributes.filename;
+
+      n.children = [
+        elem("div", { class: "filename" }, text(filename)),
+        rawHTML(highlighted),
+      ];
+    } else {
+      if (sourceCodeNode.kind === "text") {
+        n.children[0] = rawHTML(highlighted);
+      } else {
+        sourceCodeNode.html = highlighted;
+      }
+    }
+  });
+}
+
+function generateTableOfContents(doc: Document) {
+  if (!doc.isTocEnabled) {
+    return;
+  }
+  const tocEntries: TocEntry[] = [];
+  const stack: TocEntry[] = [];
+  const excludedLevels: number[] = []; // Track levels to exclude
+
+  const processNode = (node: Node) => {
+    if (node.kind !== "element") {
+      return;
+    }
+
+    const match = node.name.match(/^h(\d+)$/);
+    if (match) {
+      const level = parseInt(match[1]);
+
+      let parentSection: Element | null = null;
+      const findParentSection = (n: Node, target: Node): Element | null => {
+        if (n.kind !== "element") return null;
+
+        for (const child of n.children) {
+          if (child === target && n.name === "section") {
+            return n;
+          }
+          const result = findParentSection(child, target);
+          if (result) return result;
+        }
+        return null;
+      };
+
+      parentSection = findParentSection(doc.root, node);
+      if (!parentSection) return;
+
+      // Check if this section has toc=false attribute
+      const tocAttribute = parentSection.attributes.toc;
+      if (tocAttribute === "false") {
+        // Add this level to excluded levels and remove deeper levels
+        excludedLevels.length = 0;
+        excludedLevels.push(level);
+        return;
+      }
+
+      // Check if this header should be excluded based on parent exclusion
+      const shouldExclude = excludedLevels.some((excludedLevel) =>
+        level > excludedLevel
+      );
+      if (shouldExclude) {
+        return;
+      }
+
+      // Clean up excluded levels that are now at same or deeper level
+      while (
+        excludedLevels.length > 0 &&
+        excludedLevels[excludedLevels.length - 1] >= level
+      ) {
+        excludedLevels.pop();
+      }
+
+      const sectionId = parentSection.attributes.id;
+      if (!sectionId) return;
+
+      let headingText = "";
+      for (const child of node.children) {
+        if (child.kind === "element" && child.name === "a") {
+          headingText = innerText(child);
+        }
+      }
+
+      const entry: TocEntry = {
+        id: sectionId,
+        text: headingText,
+        level: level,
+        children: [],
+      };
+
+      while (stack.length > 0 && stack[stack.length - 1].level >= level) {
+        stack.pop();
+      }
+
+      if (stack.length === 0) {
+        tocEntries.push(entry);
+      } else {
+        stack[stack.length - 1].children.push(entry);
+      }
+
+      stack.push(entry);
+    }
+
+    forEachChild(node, processNode);
+  };
+
+  forEachChild(doc.root, processNode);
+
+  // Don't generate TOC if there's only one top-level section with no children
+  if (tocEntries.length === 1 && tocEntries[0].children.length === 0) {
+    return;
+  }
+
+  doc.toc = {
+    entries: tocEntries,
+  };
+}
+
+function removeTocAttributes(doc: Document) {
+  forEachChildRecursively(doc.root, (node) => {
+    if (node.kind === "element" && node.name === "section") {
+      delete node.attributes.toc;
+    }
+  });
+}