feat(new tool): Markdown TOC Generator

Fix #573

src/tools/markdown-toc-generator/markdown-toc-generator.service.ts

@@ -0,0 +1,178 @@
+function stripNonLatinCharacters(text: string) {
+  return text.replace(/[^A-Za-z\u00C0-\u00D6\u00D8-\u00F6\u00F8-\u00FF\u02BB\u02EE\uA78C\d\s_-]/g, '');
+};
+
+function transformInlineCode(text: string, transform: (s: string) => string) {
+  return text.replace(/`(.*?)`/g, (_, p) => {
+    return `\`${transform(p)}\``;
+  });
+};
+
+function spacesToDash(text: string) {
+  return text.replace(/\s/g, '-');
+};
+
+function stripHtmlTags(text: string) {
+  return text.replace(/<.*?>/g, '');
+};
+
+function stripMarkdownLinks(text: string, replacement: string = '$1') {
+  return text.replace(/\[([^\]]*)\]\([^\)]*\)/g, replacement);
+};
+
+function concatDashes(text: string) {
+  return text.replace(/--+/g, '-');
+};
+
+function removeUnderscoreBoldAndItalics(text: string) {
+  const underscoreBoldAndItalicsRegexes = ['__', '_'].map((it) => {
+    return new RegExp(`\\b${it}([^_\\s]|[^_\\s].*?[^_\\s])${it}\\b`, 'g');
+  });
+
+  let result = text;
+
+  underscoreBoldAndItalicsRegexes.forEach((regex) => {
+    result = result.replace(regex, '$1');
+  });
+  return result;
+};
+
+function genericAnchorGenerator(text: string, concatSpaces: boolean) {
+  let result = text;
+  result = result.toLowerCase();
+  result = transformInlineCode(result, (s: string) => {
+    return stripNonLatinCharacters(s);
+  });
+  result = removeUnderscoreBoldAndItalics(result);
+  result = stripHtmlTags(result);
+  result = stripMarkdownLinks(result);
+  result = result.trim();
+  result = stripNonLatinCharacters(result);
+  result = spacesToDash(result);
+  if (concatSpaces) {
+    result = concatDashes(result);
+  }
+  return result;
+};
+
+function escapeRegExp(string: string) {
+  return string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'); // $& means the whole matched string
+}
+
+interface Title {
+  level: number
+  id: string
+  name: string
+  md: string
+}
+
+function getTitles(markdown: string, idGenerator: (titleMarkdownContent: string) => string) {
+  const titles: Title[] = [];
+
+  markdown = markdown.replace(/^```[\s\S]*?\n```/mg, () => {
+    return '';
+  });
+  markdown = markdown.replace(/^~~~[\s\S]*?\n~~~/mg, () => {
+    return '';
+  });
+
+  [...markdown.matchAll(/^(#+)(.*$)/mg)].forEach(
+    ([match, levelString, titleContent]) => {
+      const level = levelString.length;
+
+      titles.push({
+        md: match,
+        level,
+        id: idGenerator(titleContent),
+        name: titleContent.trim(),
+      });
+    });
+
+  return titles;
+};
+
+export function getTocMarkdown({
+  markdown,
+  generateAnchors = true,
+  indentChars = '-*+',
+  indentSpaces = 2,
+  maxLevel = -1,
+  anchorPrefix = '',
+  concatSpaces = true,
+  commentStyle = 'html',
+}: {
+  markdown: string
+  generateAnchors?: boolean
+  indentChars?: string
+  indentSpaces?: number
+  maxLevel?: number
+  anchorPrefix?: string
+  concatSpaces?: boolean
+  commentStyle?: 'html' | 'liquid'
+}) {
+  const allIds: { [id: string]: number } = {};
+  const getFinalId = (id: string) => {
+    if (typeof allIds[id] === 'undefined') {
+      allIds[id] = 0;
+      return id;
+    }
+    else {
+      allIds[id] += 1;
+      return `${id}-${allIds[id]}`;
+    }
+  };
+  const titles = getTitles(markdown, titleContent => getFinalId(genericAnchorGenerator(titleContent, concatSpaces)));
+
+  const createLink = (linkText: string, url: string) => {
+    return `[${linkText.replace('[', '\\[').replace(']', '\\]')}](${url.replace('(', '%28').replace(')', '%29')})`;
+  };
+
+  let markdownTOC = '';
+  let resultMarkdown = markdown;
+  const commentOpen = commentStyle === 'html' ? '<!--' : '{%- #';
+  const commentClose = commentStyle === 'html' ? '-->' : '-%}';
+
+  resultMarkdown = resultMarkdown.replace(
+    new RegExp(`\n${commentOpen} TOC START.*?TOC END ${commentClose}\n`, 'smg'),
+    '\n[TOC]\n',
+  );
+  resultMarkdown = resultMarkdown.replace(
+    new RegExp(`^${commentOpen} TOC ANCHOR.*?\n`, 'mg'),
+    '',
+  );
+
+  titles.forEach((title) => {
+    if (title.level === 1) {
+      return;
+    }
+
+    if (maxLevel > 0 && title.level > maxLevel) {
+      return;
+    }
+
+    const level = title.level - 2;
+    let offset = '';
+    if (level) {
+      offset = `${Array.from({ length: level * indentSpaces }).join(' ')} `;
+    }
+    const bulletChar = indentChars[level] ?? indentChars.slice(-1)[0];
+
+    const anchorName = `${anchorPrefix}${title.id}`;
+
+    markdownTOC += `${offset}${bulletChar} ${createLink(stripMarkdownLinks(title.name), `#${anchorName}`)}\n`;
+
+    if (generateAnchors) {
+      resultMarkdown = resultMarkdown.replace(
+        new RegExp(`(?<!^${commentOpen} TOC ANCHOR.*\n)^${escapeRegExp(title.md)}`, 'm'),
+          `${commentOpen} TOC ANCHOR ${commentClose}<a name="${title.id}"></a>\n${title.md}`,
+      );
+    }
+  });
+
+  resultMarkdown = resultMarkdown.replace(
+    /^\[TOC\]\n/mg,
+    `${commentOpen} TOC START ${commentClose}\n${markdownTOC}${commentOpen} TOC END ${commentClose}\n`,
+  );
+
+  return resultMarkdown;
+}