feat: implement hack for journal post RSS feed

Astro is currently not able to render the compiled HTML of MDX files to a string.
This makes it impossible to render the content for an RSS feed.

Issue: Container API: render components in isolation
https://github.com/withastro/roadmap/issues/533

Proposal: MDX compiledContent() support
https://github.com/withastro/roadmap/discussions/419

To still be able to have full content for RSS feeds, this dirty hack,
Scott Willsey writes about in his 2-part blog post is needed:

https://scottwillsey.com/rss-pt1/
https://scottwillsey.com/rss-pt2/

src/components/RssXml.astro

@@ -0,0 +1,41 @@
+---
+import { site } from '../data/site';
+import { dateToISO } from '../utils';
+
+import { mapping } from '../mdx-components';
+
+const { allPosts } = Astro.props;
+const rssHeaderXml = `<?xml version="1.0" encoding="UTF-8"?>
+<rss version="2.0" xmlns:content="http://purl.org/rss/1.0/modules/content/">
+	<channel>
+		<title>${site.title}</title>
+		<description><![CDATA[ ${site.description} ]]></description>
+		<link>${site.url}</link>`;
+
+const rssFooterXml = `	</channel>
+</rss>`;
+---
+
+<Fragment set:html={rssHeaderXml} />
+{
+	allPosts.map((post: any) => (
+		<>
+			<Fragment
+				set:html={`    <item>
+			<title>${post.frontmatter.title}</title>
+			<link>${`${site.url}/${post.frontmatter.slug}/`}</link>
+			<guid>${`${site.url}/${post.frontmatter.slug}/`}</guid>
+			<description><![CDATA[${post.frontmatter.description}]]></description>
+			<pubDate>${dateToISO(post.frontmatter.date)}</pubDate>
+			<content:encoded><![CDATA[`}
+			/>
+			<post.Content components={mapping} />
+			<Fragment
+				set:html={`]]></content:encoded>
+		</item>
+`}
+			/>
+		</>
+	))
+}
+<Fragment set:html={rssFooterXml} />

src/components/WriteFile.astro

@@ -0,0 +1,13 @@
+---
+import path from 'node:path';
+import fs from 'node:fs/promises';
+
+const distFolder = './dist';
+const filename = 'rss.xml';
+const fileUrl = path.join(distFolder, filename);
+
+if (Astro.slots.has('rss-writer')) {
+	const html = await Astro.slots.render('rss-writer');
+	await fs.writeFile(fileUrl, html);
+}
+---

src/layouts/BaseLayout.astro

@@ -178,5 +178,6 @@ const webManifest = isProduction && {
 				@apply overflow-auto rounded-2 p-[1em] font-mono text-code mbe-10 mbs-0;
 			}
 		</style>
+		<slot name="rss-writer" />
 	</body>
 </html>

src/pages/index.astro

@@ -1,7 +1,7 @@
 ---
 import { getCollection } from 'astro:content';
 
-import { formatPosts } from '../utils';
+import { formatPosts, isProduction, sortMarkdownByDate } from '../utils';
 
 import { site, animation, animationDelay } from '../data/site';
 
@@ -12,6 +12,13 @@ import PageTitle from '../components/PageTitle.astro';
 import Picture from '../components/Picture.astro';
 import JournalList from '../components/JournalList.astro';
 
+/* FIXME: Remove hack as soon as this issue is resolved:
+ * Issue: https://github.com/withastro/roadmap/issues/533
+ * Proposal: https://github.com/withastro/roadmap/discussions/419
+ */
+import WriteFile from '../components/WriteFile.astro';
+import RssXml from '../components/RssXml.astro';
+
 import { Headline } from '../components';
 
 import { Content as AboutMe } from '../text/homepage/about-me.mdx';
@@ -25,6 +32,9 @@ const formattedLatest = formatPosts(allPosts, { limit: 6 });
 
 const title = 'Stefan Imhoff';
 const description = 'Front-End Web Developer from Hamburg, Germany';
+
+const rssPosts = await Astro.glob('../content/journal/**/*.mdx');
+rssPosts.sort(sortMarkdownByDate);
 ---
 
 <GridLayout title={title} description={description} grid="fullsize" class="grid" innerGrid>
@@ -81,3 +91,7 @@ const description = 'Front-End Web Developer from Hamburg, Germany';
 		<JournalList entries={formattedLatest} />
 	</article>
 </GridLayout>
+
+<WriteFile slot="rss-writer">
+	<RssXml allPosts={isProduction ? rssPosts : []} slot="rss-writer" />
+</WriteFile>

src/utils/sort-by-date.ts

@@ -1,3 +1,7 @@
 export const sortByDate = (a: any, b: any) => {
 	return Date.parse(b.data.date.toISOString()) - Date.parse(a.data.date.toISOString());
 };
+
+export const sortMarkdownByDate = (a: any, b: any) => {
+	return Date.parse(b.frontmatter.date) - Date.parse(a.frontmatter.date);
+};