From f1ccf4fcc8928f6349475a1ec8fe02c10325670e Mon Sep 17 00:00:00 2001
From: Titus Wormer <tituswormer@gmail.com>
Date: Mon, 16 Sep 2024 17:32:10 +0200
Subject: [PATCH] node-loader: add support for options w/ `initialize`

---
 packages/node-loader/index.js            |  5 +++
 packages/node-loader/lib/index.js        | 42 ++++++++++++++++++------
 website/loader.js                        | 11 +++++--
 website/{mdx-config.js => mdx-loader.js} |  5 ++-
 4 files changed, 49 insertions(+), 14 deletions(-)
 rename website/{mdx-config.js => mdx-loader.js} (99%)

diff --git a/packages/node-loader/index.js b/packages/node-loader/index.js
index a13d7072a..6898f36bd 100644
--- a/packages/node-loader/index.js
+++ b/packages/node-loader/index.js
@@ -8,6 +8,11 @@ const defaultLoader = createLoader()
 
 export {createLoader} from './lib/index.js'
 
+/**
+ * Pass options to the loader.
+ */
+export const initialize = defaultLoader.initialize
+
 /**
  * Load `file:` URLs to MD(X) files.
  */
diff --git a/packages/node-loader/lib/index.js b/packages/node-loader/lib/index.js
index e1e70cf91..71b8c7cc1 100644
--- a/packages/node-loader/lib/index.js
+++ b/packages/node-loader/lib/index.js
@@ -1,5 +1,6 @@
 /**
  * @import {LoadFnOutput, LoadHook, LoadHookContext} from 'node:module'
+ * @import {Process} from '@mdx-js/mdx/internal-create-format-aware-processors'
  * @import {CompileOptions} from '@mdx-js/mdx'
  */
 
@@ -14,6 +15,8 @@
  *   exception that the `development` option is supported based on
  *   whether you run Node with `--conditions development`.
  *   You cannot pass it manually.
+ *
+ * @typedef {[regex: RegExp, process: Process]} Settings
  */
 
 import fs from 'node:fs/promises'
@@ -27,21 +30,24 @@ import {development as defaultDevelopment} from '#condition'
 /**
  * Create Node.js hooks to handle markdown and MDX.
  *
- * @param {Readonly<Options> | null | undefined} [options]
+ * @param {Readonly<Options> | null | undefined} [loaderOptions]
  *   Configuration (optional).
  * @returns
  *   Node.js hooks.
  */
-export function createLoader(options) {
-  const options_ = options || {}
-  const {extnames, process} = createFormatAwareProcessors({
-    development: defaultDevelopment,
-    ...options_,
-    SourceMapGenerator
-  })
-  const regex = extnamesToRegex(extnames)
+export function createLoader(loaderOptions) {
+  /** @type {Settings} */
+  let settings = configure(loaderOptions || {})
 
-  return {load}
+  return {initialize, load}
+
+  /**
+   *
+   * @param {Readonly<Options> | null | undefined} options
+   */
+  async function initialize(options) {
+    settings = configure({...loaderOptions, ...options})
+  }
 
   /**
    * Load `file:` URLs to MD(X) files.
@@ -58,6 +64,7 @@ export function createLoader(options) {
    */
   async function load(href, context, nextLoad) {
     const url = new URL(href)
+    const [regex, process] = settings
 
     if (url.protocol === 'file:' && regex.test(url.pathname)) {
       const value = await fs.readFile(url)
@@ -82,3 +89,18 @@ export function createLoader(options) {
     return nextLoad(href, context)
   }
 }
+
+/**
+ * @param {Readonly<Options>} options
+ * @returns {Settings}
+ */
+function configure(options) {
+  const {extnames, process} = createFormatAwareProcessors({
+    development: defaultDevelopment,
+    ...options,
+    SourceMapGenerator
+  })
+  const regex = extnamesToRegex(extnames)
+
+  return [regex, process]
+}
diff --git a/website/loader.js b/website/loader.js
index 85c49fa11..d26742aad 100644
--- a/website/loader.js
+++ b/website/loader.js
@@ -1,6 +1,11 @@
-import {createLoader as createMdxLoader} from '@mdx-js/node-loader'
 import {createLoader as createJsxLoader} from '../script/jsx-loader.js'
-import config from './mdx-config.js'
+import {initialize, load} from './mdx-loader.js'
 
-const loader = {loaders: [createJsxLoader(), createMdxLoader(config)]}
+const loader = {loaders: [createJsxLoader(), {initialize, load}]}
 export default loader
+
+// To do: after dropping Node 18:
+// import {register} from 'node:module'
+
+// register('../script/jsx-loader.js', import.meta.url)
+// register('./mdx-loader.js', import.meta.url)
diff --git a/website/mdx-config.js b/website/mdx-loader.js
similarity index 99%
rename from website/mdx-config.js
rename to website/mdx-loader.js
index b045b5c80..fd96f813d 100644
--- a/website/mdx-config.js
+++ b/website/mdx-loader.js
@@ -16,6 +16,7 @@
 
 import assert from 'node:assert/strict'
 import {fileURLToPath, pathToFileURL} from 'node:url'
+import {createLoader} from '@mdx-js/node-loader'
 import {nodeTypes} from '@mdx-js/mdx'
 import {common} from '@wooorm/starry-night'
 import sourceMdx from '@wooorm/starry-night/source.mdx'
@@ -117,7 +118,9 @@ const options = {
   ]
 }
 
-export default options
+const {initialize, load} = createLoader(options)
+
+export {initialize, load}
 
 function link() {
   return s(