Also compress Docusaurus-generated files

Run the compression manually for files that are not generated by Webpack.

We must take over the @docusaurus/plugin-sitemap plugin to make sure we run
after it has generated sitemap.xml. Docusaurus runs all plugin post-build
actions in parallel with Promise.all, so the only way to do this is to invoke
the post-build action in our own one.

4 files changed, 44 insertions, 14 deletions

diff --git a/docusaurus.config.ts b/docusaurus.config.ts
index f19513a..9468812 100644
--- a/docusaurus.config.ts
+++ b/docusaurus.config.ts
@@ -23,7 +23,6 @@ export default {
         remarkPlugins: [[smartypants, { dashes: 'oldschool' }]],
       },
     ],
-    '@docusaurus/plugin-sitemap',
     './src/plugins/compressionPlugin.ts',
     './src/plugins/responsiveLoaderPlugin.ts',
     './src/plugins/swcMinifyPlugin.ts',
diff --git a/package.json b/package.json
index 74600da..57e8f60 100644
--- a/package.json
+++ b/package.json
@@ -32,6 +32,7 @@
     "@docusaurus/plugin-sitemap": "^3.1.1",
     "@docusaurus/theme-classic": "^3.1.1",
     "@docusaurus/theme-common": "^3.1.1",
+    "@docusaurus/utils": "^3.1.1",
     "@mdx-js/react": "^3.0.1",
     "@phosphor-icons/react": "2.1.3",
     "@swc/core": "^1.4.8",
diff --git a/src/plugins/compressionPlugin.ts b/src/plugins/compressionPlugin.ts
index b1cff6a..8b347cf 100644
--- a/src/plugins/compressionPlugin.ts
+++ b/src/plugins/compressionPlugin.ts
@@ -4,14 +4,35 @@
  * SPDX-License-Identifier: MIT
  */
 
-import zlib, { type BrotliOptions } from 'node:zlib';
+import { readFile, writeFile } from 'node:fs/promises';
+import path from 'node:path';
+import { promisify } from 'node:util';
+import zlib, { type BrotliOptions, type ZlibOptions } from 'node:zlib';
 
-import type { Plugin } from '@docusaurus/types';
+import pluginSitemap, { type PluginOptions } from '@docusaurus/plugin-sitemap';
+import type { LoadContext, Plugin } from '@docusaurus/types';
+import { Globby } from '@docusaurus/utils';
 import CompressionPlugin from 'compression-webpack-plugin';
 
-const test = /\.(js|css|html|svg|txt)$/;
+const gzipOptions = {
+  level: 9,
+} satisfies ZlibOptions;
+const brotliOptions = {
+  params: {
+    [zlib.constants.BROTLI_PARAM_QUALITY]: 11,
+  },
+};
+const test = /\.(js|css|svg|txt)$/;
+const paths = ['**/*.html', 'robots.txt', 'sitemap.xml'];
 
-export default function compressionPlugin(): Plugin {
+const gzip = promisify(zlib.gzip);
+const brotliCompress = promisify(zlib.brotliCompress);
+
+export default function compressionPlugin(
+  context: LoadContext,
+  options: PluginOptions,
+): Plugin<void> {
+  const sitemap = pluginSitemap(context, options);
   return {
     name: 'marussy-compression-plugin',
     configureWebpack: (_config, isServer) =>
@@ -22,21 +43,29 @@ export default function compressionPlugin(): Plugin {
               new CompressionPlugin({
                 test,
                 filename: '[path][base].gz',
-                compressionOptions: {
-                  level: 9,
-                },
+                compressionOptions: gzipOptions,
               }),
               new CompressionPlugin<BrotliOptions>({
                 test,
                 filename: '[path][base].br',
                 algorithm: 'brotliCompress',
-                compressionOptions: {
-                  params: {
-                    [zlib.constants.BROTLI_PARAM_QUALITY]: 11,
-                  },
-                },
+                compressionOptions: brotliOptions,
               }),
             ],
           },
+    async postBuild(props) {
+      await sitemap?.postBuild(props);
+      const files = await Globby(paths.map((s) => path.join(props.outDir, s)));
+      for (const file of files) {
+        console.log(file);
+        const contents = await readFile(file);
+        const gzipContents = await gzip(contents, gzipOptions);
+        await writeFile(`${file}.gz`, gzipContents);
+        const brotliContents = await brotliCompress(contents, brotliOptions);
+        await writeFile(`${file}.br`, brotliContents);
+      }
+    },
   };
 }
+
+export { validateOptions } from '@docusaurus/plugin-sitemap';
diff --git a/yarn.lock b/yarn.lock
index c876b9c..b957685 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1865,7 +1865,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@docusaurus/utils@npm:3.1.1":
+"@docusaurus/utils@npm:3.1.1, @docusaurus/utils@npm:^3.1.1":
   version: 3.1.1
   resolution: "@docusaurus/utils@npm:3.1.1"
   dependencies:
@@ -7505,6 +7505,7 @@ __metadata:
     "@docusaurus/theme-common": "npm:^3.1.1"
     "@docusaurus/tsconfig": "npm:^3.1.1"
     "@docusaurus/types": "npm:^3.1.1"
+    "@docusaurus/utils": "npm:^3.1.1"
     "@mdx-js/react": "npm:^3.0.1"
     "@phosphor-icons/react": "npm:2.1.3"
     "@swc/core": "npm:^1.4.8"