From 285b2f67e967286019f0f29d1f0921134347a586 Mon Sep 17 00:00:00 2001
From: Nantha Sorubakanthan <nantha@mielota.com>
Date: Mon, 3 Nov 2025 19:58:32 +0100
Subject: Syntax highlighting from javascript script

---
 .gitignore            |  2 ++
 package.json          | 13 ++++++++++++
 scripts/highlight.mjs | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 72 insertions(+)
 create mode 100644 package.json
 create mode 100644 scripts/highlight.mjs

diff --git a/.gitignore b/.gitignore
index c4b387a..191d1a1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 .hugo_build.lock
 public/
+node_modules/
+package-lock.json
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..0d3ac30
--- /dev/null
+++ b/package.json
@@ -0,0 +1,13 @@
+{
+	"scripts": {
+		"build": "hugo && npm run highlight",
+		"highlight": "node scripts/highlight.mjs"
+	},
+	"dependencies": {
+		"dom-serializer": "^2.0.0",
+		"domutils": "^3.2.2",
+		"glob": "^11.0.3",
+		"htmlparser2": "^10.0.0",
+		"shiki": "^3.14.0"
+	}
+}
diff --git a/scripts/highlight.mjs b/scripts/highlight.mjs
new file mode 100644
index 0000000..2870866
--- /dev/null
+++ b/scripts/highlight.mjs
@@ -0,0 +1,57 @@
+import { createHighlighter, bundledLanguages } from 'shiki';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { readFile, writeFile } from 'node:fs/promises';
+import { glob } from 'glob';
+import { parseDocument } from 'htmlparser2';
+import { findAll, findOne, textContent, replaceElement } from 'domutils';
+import render from 'dom-serializer';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+main();
+
+async function main() {
+	const LIGHT_THEME = 'github-dark';
+	const DARK_THEME = LIGHT_THEME;
+
+	const start = Date.now();
+
+	const highlighter = await createHighlighter({
+		themes: [LIGHT_THEME, DARK_THEME],
+		langs: Object.keys(bundledLanguages),
+	});
+
+	const files = await glob(join(__dirname, '../public/**/**/index.html'));
+	await Promise.all(
+		files.map((filepath) => highlightFile(highlighter, filepath, { lightTheme: LIGHT_THEME, darkTheme: DARK_THEME }))
+	);
+
+	console.log(`Highlighted ${files.length} files in ${Math.round(Date.now() - start)} ms`);
+}
+
+async function highlightFile(highlighter, filepath, { lightTheme, darkTheme }) {
+	const contents = await readFile(filepath, { encoding: 'utf-8' });
+	await writeFile(filepath, highlightHtmlContent(highlighter, contents, { lightTheme, darkTheme }));
+}
+
+function highlightHtmlContent(highlighter, htmlContent, { lightTheme, darkTheme }) {
+	const doc = parseDocument(htmlContent);
+	for (const preNode of findAll((e) => e.name === 'pre', doc.children)) {
+		const codeNode = findOne((e) => e.name === 'code', preNode.children);
+		if (!codeNode) continue;
+
+		const lang = codeNode.attribs['class']?.replace(/^language-/, '') ?? 'text';
+		const code = textContent(codeNode);
+		const highlighted = highlighter.codeToHtml(code, {
+			lang,
+			themes: { light: lightTheme, dark: darkTheme },
+		});
+
+		const highlightedPreNode = parseDocument(highlighted).children[0];
+		replaceElement(preNode, highlightedPreNode);
+	}
+
+	return render(doc);
+}
+
-- 
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