1 files changed, 118 insertions, 0 deletions
diff --git a/packages/integrations/markdoc/src/load-config.ts b/packages/integrations/markdoc/src/load-config.ts
new file mode 100644
index 000000000..ce181e604
--- /dev/null
+++ b/packages/integrations/markdoc/src/load-config.ts
@@ -0,0 +1,118 @@
+import * as fs from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import type { AstroConfig } from 'astro';
+import { build as esbuild } from 'esbuild';
+import type { AstroMarkdocConfig } from './config.js';
+import { MarkdocError } from './utils.js';
+
+export const SUPPORTED_MARKDOC_CONFIG_FILES = [
+	'markdoc.config.js',
+	'markdoc.config.mjs',
+	'markdoc.config.mts',
+	'markdoc.config.ts',
+];
+
+export type MarkdocConfigResult = {
+	config: AstroMarkdocConfig;
+	fileUrl: URL;
+};
+
+export async function loadMarkdocConfig(
+	astroConfig: Pick<AstroConfig, 'root'>,
+): Promise<MarkdocConfigResult | undefined> {
+	let markdocConfigUrl: URL | undefined;
+	for (const filename of SUPPORTED_MARKDOC_CONFIG_FILES) {
+		const filePath = new URL(filename, astroConfig.root);
+		if (!fs.existsSync(filePath)) continue;
+
+		markdocConfigUrl = filePath;
+		break;
+	}
+	if (!markdocConfigUrl) return;
+
+	const { code } = await bundleConfigFile({
+		markdocConfigUrl,
+		astroConfig,
+	});
+	const config: AstroMarkdocConfig = await loadConfigFromBundledFile(astroConfig.root, code);
+
+	return {
+		config,
+		fileUrl: markdocConfigUrl,
+	};
+}
+
+/**
+ * Bundle config file to support `.ts` files.
+ * Simplified fork from Vite's `bundleConfigFile` function:
+ * @see https://github.com/vitejs/vite/blob/main/packages/vite/src/node/config.ts#L961
+ */
+async function bundleConfigFile({
+	markdocConfigUrl,
+	astroConfig,
+}: {
+	markdocConfigUrl: URL;
+	astroConfig: Pick<AstroConfig, 'root'>;
+}): Promise<{ code: string; dependencies: string[] }> {
+	let markdocError: MarkdocError | undefined;
+
+	const result = await esbuild({
+		absWorkingDir: fileURLToPath(astroConfig.root),
+		entryPoints: [fileURLToPath(markdocConfigUrl)],
+		outfile: 'out.js',
+		write: false,
+		target: ['node16'],
+		platform: 'node',
+		packages: 'external',
+		bundle: true,
+		format: 'esm',
+		sourcemap: 'inline',
+		metafile: true,
+		plugins: [
+			{
+				name: 'stub-astro-imports',
+				setup(build) {
+					build.onResolve({ filter: /.*\.astro$/ }, () => {
+						// Avoid throwing within esbuild.
+						// This swallows the `hint` and blows up the stacktrace.
+						markdocError = new MarkdocError({
+							message: '`.astro` files are no longer supported in the Markdoc config.',
+							hint: 'Use the `component()` utility to specify a component path instead. See https://docs.astro.build/en/guides/integrations-guide/markdoc/',
+						});
+						return {
+							// Stub with an unused default export.
+							path: 'data:text/javascript,export default true',
+							external: true,
+						};
+					});
+				},
+			},
+		],
+	});
+	if (markdocError) throw markdocError;
+	const { text } = result.outputFiles[0];
+	return {
+		code: text,
+		dependencies: result.metafile ? Object.keys(result.metafile.inputs) : [],
+	};
+}
+
+/**
+ * Forked from Vite config loader, replacing CJS-based path concat
+ * with ESM only
+ * @see https://github.com/vitejs/vite/blob/main/packages/vite/src/node/config.ts#L1074
+ */
+async function loadConfigFromBundledFile(root: URL, code: string): Promise<AstroMarkdocConfig> {
+	// Write it to disk, load it with native Node ESM, then delete the file.
+	const tmpFileUrl = new URL(`markdoc.config.timestamp-${Date.now()}.mjs`, root);
+	fs.writeFileSync(tmpFileUrl, code);
+	try {
+		return (await import(tmpFileUrl.pathname)).default;
+	} finally {
+		try {
+			fs.unlinkSync(tmpFileUrl);
+		} catch {
+			// already removed if this function is called twice simultaneously
+		}
+	}
+}