From 1f0dd31d9239b5e3dca99c88d021e7a9a3e2054d Mon Sep 17 00:00:00 2001
From: Nate Moore <natemoo-re@users.noreply.github.com>
Date: Thu, 11 Aug 2022 10:59:48 -0500
Subject: [PATCH] fix(#4246): fix Prism indentation and class (#4251)

Co-authored-by: Nate Moore <nate@astro.build>
---
 .changeset/old-pears-design.md          | 7 +++++++
 packages/astro-prism/Prism.astro        | 6 +-----
 packages/astro-prism/src/highlighter.ts | 4 +---
 3 files changed, 9 insertions(+), 8 deletions(-)
 create mode 100644 .changeset/old-pears-design.md

diff --git a/.changeset/old-pears-design.md b/.changeset/old-pears-design.md
new file mode 100644
index 000000000000..e31be82ac5a2
--- /dev/null
+++ b/.changeset/old-pears-design.md
@@ -0,0 +1,7 @@
+---
+'@astrojs/prism': patch
+---
+
+Fix `<Prism />` component indentation
+
+Prefer `class="language-plaintext"` to `class="language-undefined"`
diff --git a/packages/astro-prism/Prism.astro b/packages/astro-prism/Prism.astro
index 44cf4748af5f..fab9dafe2782 100644
--- a/packages/astro-prism/Prism.astro
+++ b/packages/astro-prism/Prism.astro
@@ -11,8 +11,4 @@ const { class: className, lang, code } = Astro.props as Props;
 const { classLanguage, html } = runHighlighterWithAstro(lang, code);
 ---
 
-<pre
-	class={[className, classLanguage].join(
-		' '
-	)}>	<code class={classLanguage}><Fragment set:html={html} /></code>
-</pre>
+<pre class={[className, classLanguage].filter(Boolean).join(' ')}><code class={classLanguage} set:html={html} /></pre>
diff --git a/packages/astro-prism/src/highlighter.ts b/packages/astro-prism/src/highlighter.ts
index 3dffefae9582..c0e58054e7ee 100644
--- a/packages/astro-prism/src/highlighter.ts
+++ b/packages/astro-prism/src/highlighter.ts
@@ -5,12 +5,10 @@ import { addAstro } from './plugin.js';
 const languageMap = new Map([['ts', 'typescript']]);
 
 export function runHighlighterWithAstro(lang: string | undefined, code: string) {
-	let classLanguage = `language-${lang}`;
-
 	if (!lang) {
 		lang = 'plaintext';
 	}
-
+	let classLanguage = `language-${lang}`;
 	const ensureLoaded = (language: string) => {
 		if (language && !Prism.languages[language]) {
 			loadLanguages([language]);