From 987a58000f940661e69d6e1d4b5270f61c9e8a2e Mon Sep 17 00:00:00 2001
From: Victor Giers <giers@MacBook-Pro.local>
Date: Fri, 5 Dec 2025 17:30:37 +0100
Subject: [PATCH] auto-git:  [add] markdown.js

---
 markdown.js | 244 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 244 insertions(+)
 create mode 100644 markdown.js

diff --git a/markdown.js b/markdown.js
new file mode 100644
index 0000000..6e52638
--- /dev/null
+++ b/markdown.js
@@ -0,0 +1,244 @@
+export function markdownToHTML(text) {
+  // 0) Remove <think>...</think>/<thinking>...</thinking> blocks
+  // This regex will match an an opening <think> or <thinking> tag,
+  // followed by any characters (non-greedy), until either a closing
+  // </think> or </thinking> tag is found, OR the end of the string ($).
+  text = text.replace(/<think(?:ing)?>[\s\S]*?(?:<\/think(?:ing)?>|$)/gi, '');
+
+  // Normalize exotic spaces (narrow/non-breaking) to regular spaces for consistent rendering
+  text = text.replace(/[\u00a0\u202f\u2007]/g, ' ');
+
+  text = balanceStreamingCodeFence(text);
+
+  const escapeHtml = (value = '') =>
+    value
+      .replace(/&/g, '&amp;')
+      .replace(/</g, '&lt;')
+      .replace(/>/g, '&gt;');
+  const escapeAttr = (value = '') =>
+    escapeHtml(value)
+      .replace(/"/g, '&quot;')
+      .replace(/'/g, '&#39;');
+  const applyInline = (source) => {
+    const codeRuns = [];
+    let tmp = source.replace(/`([^`]+?)`/g, (_, code) => {
+      const idx = codeRuns.push(code) - 1;
+      return `@@CODEINLINE${idx}@@`;
+    });
+
+    const strongRuns = [];
+    tmp = tmp.replace(/\*\*([\s\S]+?)\*\*/g, (_, content) => {
+      const idx = strongRuns.push(content) - 1;
+      return `@@STRONG${idx}@@`;
+    });
+
+    const emphasisRuns = [];
+    tmp = tmp.replace(/(?<!\*)\*([\s\S]+?)\*(?!\*)/g, (_, content) => {
+      const idx = emphasisRuns.push(content) - 1;
+      return `@@EM${idx}@@`;
+    });
+
+    return tmp
+      .replace(/@@STRONG(\d+)@@/g, (_, idx) => `<b>${strongRuns[+idx]}</b>`)
+      .replace(/@@EM(\d+)@@/g,      (_, idx) => `<i>${emphasisRuns[+idx]}</i>`)
+      .replace(/@@CODEINLINE(\d+)@@/g, (_, idx) => `<code>${codeRuns[+idx]}</code>`);
+  };
+
+  // 1) Normalize line endings
+  let tmp = text.replace(/\r\n/g, '\n').replace(/\r/g, '\n');
+
+  // 2) Extract code blocks and replace with placeholders (protect from all formatting)
+  const codeblocks = [];
+  const placeholder = idx => `@@CODEBLOCK${idx}@@`;
+  tmp = tmp.replace(/```([^\n]*)\n([\s\S]*?)```/g, (_, lang, code) => {
+    // Strip trailing whitespace-only lines at the end of the block
+    let cleaned = (code || '').replace(/\r\n/g, '\n').replace(/\r/g, '\n');
+    const lines = cleaned.split('\n');
+    while (lines.length > 0 && /^\s*$/.test(lines[lines.length - 1])) lines.pop();
+    cleaned = lines.join('\n');
+    codeblocks.push({ lang: (lang || '').trim(), code: cleaned });
+    return placeholder(codeblocks.length - 1);
+  });
+
+  // 3) HTML-escape special characters (outside of code blocks)
+  let escaped = escapeHtml(tmp);
+
+  // 4) Headings
+  escaped = escaped
+    .replace(/^#### (.+)$/gm, "<h4>$1</h4>")
+    .replace(/^### (.+)$/gm, "<h3>$1</h3>")
+    .replace(/^## (.+)$/gm,  "<h2>$1</h2>")
+    .replace(/^# (.+)$/gm,   "<h1>$1</h1>");
+
+  // 4.3) Blockquotes
+  escaped = escaped.replace(
+    /(^|\n)([ \t]*> .+(?:\n[ \t]*> .+)*)/g,
+    (_, lead, blockquoteBlock) => {
+      const lines = blockquoteBlock
+        .split(/\n/)
+        .map(line => line.replace(/^[ \t]*>\s*/, '').trim())
+        .join('\n');
+      return `${lead}<blockquote>${lines}</blockquote>`;
+    }
+  );
+
+  // 4.5) Unordered lists
+  escaped = escaped.replace(
+    /(^|\n)([ \t]*[-*] .+(?:\n[ \t]*[-*] .+)*)/g,
+    (_, lead, listBlock) => {
+      const items = listBlock
+        .split(/\n/)
+        .map(line => line.replace(/^[ \t]*[-*]\s+/, '').trim())
+        .map(item => `<li>${item}</li>`)
+        .join('');
+      return `${lead}<ul>${items}</ul>`;
+    }
+  );
+
+  // 4.6) Markdown tables (GitHub-style). Strict: requires header, separator, ≥2 cols.
+  const mdTableBlockRe =
+    /(^\|[^\n]*\|?\s*\n\|\s*[:\-]+(?:\s*\|\s*[:\-]+)+\s*\|?\s*\n(?:\|[^\n]*\|?\s*(?:\n|$))*)/gm;
+
+  escaped = escaped.replace(mdTableBlockRe, (block) => {
+    const hadTrailingNewline = /\n$/.test(block);
+    const lines = block.replace(/\n$/, '').split('\n');
+
+    const split = (line) => line.replace(/^\||\|$/g, '').split('|').map(s => s.trim());
+
+    const headers = split(lines[0]);
+    const seps    = split(lines[1]);
+    if (headers.length < 2 || seps.length < 2) return block;
+    if (!seps.every(s => /^[ :\-]+$/.test(s) && /-/.test(s))) return block;
+
+    const aligns = seps.map(seg => {
+      const s = seg.replace(/\s+/g,'');
+      const left = s.startsWith(':');
+      const right = s.endsWith(':');
+      if (left && right) return 'center';
+      if (right) return 'right';
+      return 'left';
+    });
+
+    const bodyLines = lines.slice(2).filter(l => /^\|/.test(l.trim()));
+    const alignClass = (i) => `md-align-${aligns[i] || 'left'}`;
+
+    const ths = headers.map((h,i)=>`<th class="md-table__head-cell ${alignClass(i)}">${h}</th>`).join('');
+    const rows = bodyLines.map(line => {
+      const cells = split(line);
+      const tds = cells.map((c,i)=>`<td class="md-table__cell ${alignClass(i)}">${c}</td>`).join('');
+      return `<tr class="md-table__row">${tds}</tr>`;
+    }).join('');
+
+    const table = `<table class="md-table"><thead><tr class="md-table__row md-table__row--head">${ths}</tr></thead><tbody>${rows}</tbody></table>`;
+
+    return table + (hadTrailingNewline ? '\n' : '');
+  });
+
+  // 4.75) Horizontal rules
+  escaped = escaped.replace(/^---\s*$/gm, "<hr>");
+
+  // 5) Bold, italic, inline code (inline code only; fenced were extracted)
+  let html = applyInline(escaped);
+
+  // 5.5) Links
+  const safeLink = (hrefRaw) => {
+    const href = (hrefRaw || '').trim();
+    if (!href) return '';
+    if (/^https?:\/\//i.test(href)) return href;
+    if (/^mailto:/i.test(href) || /^tel:/i.test(href)) return href;
+    if (href.startsWith('/') || href.startsWith('#')) return href;
+    return '';
+  };
+
+  html = html.replace(/\[([^\]]+?)\]\(([^)]+?)\)/g, (_, label, href) => {
+    const url = safeLink(href);
+    const tooltip = escapeHtml(href || '');
+    if (!url) return label;
+    return `<a class="md-link md-link--external" href="${escapeAttr(url)}" target="_blank" rel="noreferrer noopener"><span class="md-link__label">${label}</span> <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" class="md-icon md-icon-external"><path d="M18 13v6a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2V8a2 2 0 0 1 2-2h6"></path><polyline points="15 3 21 3 21 9"></polyline><line x1="10" y1="14" x2="21" y2="3"></line></svg><span class="md-link__tooltip">${tooltip}</span></a>`;
+  });
+
+  // 6) Convert line-breaks to <br> for NON-code content (code is still placeholdered)
+  html = html.replace(/\n/g, "<br>");
+
+  // 6.1) Light cleanup: collapse 3+ consecutive <br> into a double-break, keep intentional spacing otherwise
+  html = html.replace(/(?:<br>[\s]*){3,}/g, "<br><br>");
+
+  // 6.2) Normalize spacing around block elements:
+  // - keep a single break before block elements when breaks exist
+  // - after a block element, keep at most one break
+  html = html
+    .replace(/(<br>\s*)+(<(?:h[1-4]|hr|table|ul|ol|blockquote)\b[^>]*>)/g, "<br>$2")
+    .replace(/(<\/(?:h[1-4]|table|ul|ol|blockquote)>\s*)(<br>\s*)+/g, "$1<br>");
+
+  // 6.3) Trim stray breaks immediately after headings but leave at most one (tighter)
+  html = html.replace(/(<\/h[1-4]>)(<br>\s*)+/g, "$1");
+  // 6.4) Trim trailing breaks after lists; rely on CSS margins for spacing
+  html = html.replace(/(<\/(?:ul|ol)>)(<br>\s*)+/g, "$1");
+  // 7) Restore code blocks with title bar (language) + copy button (no inline handlers)
+  html = html.replace(/@@CODEBLOCK(\d+)@@/g, (_, idx) => {
+    const { lang, code } = codeblocks[+idx];
+    const title = (lang && lang.trim()) ? lang.trim() : 'code';
+    const titleLabel = escapeHtml(title);
+    const languageClass = title.toLowerCase().replace(/[^a-z0-9_-]/g, '') || 'code';
+
+    // Escape only for HTML rendering inside <code>; keep raw \n (no <br> here!)
+    const escapedCode = escapeHtml(code);
+
+    // Single-line header to avoid global <br> interference
+    const encodedForCopy = encodeURIComponent(code);
+    const head = `<div class="md-codeblock__header"><div class="md-codeblock__lang">${titleLabel}</div><button type="button" class="md-codeblock__copy" aria-label="Copy code" title="Copy code" data-copy-code="${escapeAttr(encodedForCopy)}"><svg class="md-icon md-icon-copy" viewBox="0 0 24 24" width="16" height="16" aria-hidden="true"><path d="M16 1H4a2 2 0 0 0-2 2v12h2V3h12V1zm3 4H8a2 2 0 0 0-2 2v14a2 2 0 0 0 2 2h11a2 2 0 0 0 2-2V7a2 2 0 0 0-2-2zm0 16H8V7h11v14z"/></svg></button></div>`;
+
+    // Ensure wrapping inside container and preserve newlines for copy/paste
+    const body = `<pre class="md-codeblock__pre"><code class="md-codeblock__code language-${languageClass}">${escapedCode}</code></pre>`;
+
+    return `<div class="md-codeblock">${head}${body}</div>`;
+  });
+
+  // 8) Final cleanup around codeblocks specifically (remove stray <br> added next to placeholders)
+  html = html
+    .replace(/<br>\s*(?=<div class="md-codeblock"\b)/g, "")                              // <br> before opening
+    .replace(/(<div class="md-codeblock"[^>]*>[\s\S]*?<\/div>)\s*<br>/g, "$1");          // <br> right after closing
+
+  return html;
+}
+
+// Virtually close an unfinished fenced code block so it renders during streaming.
+function balanceStreamingCodeFence(md) {
+  // Split into lines; we only consider fences that start a line.
+  const lines = md.split(/\r?\n/);
+
+  // Track the last unmatched opening fence we see while scanning.
+  // { fenceChar: '`' or '~', fenceLen: number }
+  let open = null;
+
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i];
+
+    // Opening fence?  ^\s*([`~]{3,})(.*)$
+    if (!open) {
+      const m = line.match(/^\s*([`~]{3,})([^\s]*)?.*$/);
+      if (m) {
+        // Treat as an opening fence
+        open = { fenceChar: m[1][0], fenceLen: m[1].length };
+        continue;
+      }
+    } else {
+      // Closing fence: must match same char and length or longer
+      const re = new RegExp(`^\\s*(${open.fenceChar}{${open.fenceLen},})\\s*$`);
+      if (re.test(line)) {
+        // Closed
+        open = null;
+        continue;
+      }
+      // Otherwise still inside the code block; keep scanning
+    }
+  }
+
+  if (open) {
+    // Virtually close with the same fence so the block renders now
+    const virtual = `${open.fenceChar.repeat(open.fenceLen)}`;
+    return md.endsWith('\n') ? md + virtual : md + '\n' + virtual;
+  }
+
+  return md;
+}