Simplify compression

Compress Docusaurus-generated files in a separate script instead of a post-build
hook to avoid post-build hook ordering and concurrency issues.

5 files changed, 79 insertions, 39 deletions

diff --git a/docusaurus.config.ts b/docusaurus.config.ts
index 9468812..f19513a 100644
--- a/docusaurus.config.ts
+++ b/docusaurus.config.ts
@@ -23,6 +23,7 @@ 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 57e8f60..fc56b75 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,7 @@
   "private": true,
   "scripts": {
     "docusaurus": "docusaurus",
-    "build": "cross-env WEBPACK_URL_LOADER_LIMIT=0 docusaurus build",
+    "build": "cross-env WEBPACK_URL_LOADER_LIMIT=0 docusaurus build && node scripts/compressSite.mjs",
     "swizzle": "docusaurus swizzle",
     "clear": "docusaurus clear",
     "serve": "docusaurus serve -p 1313 --no-open",
diff --git a/scripts/compressSite.mjs b/scripts/compressSite.mjs
new file mode 100644
index 0000000..bd98c55
--- /dev/null
+++ b/scripts/compressSite.mjs
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2024 Kristóf Marussy <kristof@marussy.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+import { readFile, writeFile } from 'node:fs/promises';
+import path from 'node:path';
+import { promisify } from 'node:util';
+import zlib from 'node:zlib';
+
+import { Globby } from '@docusaurus/utils';
+
+import { brotliOptions, gzipOptions, minRatio } from './compressionOptions.mjs';
+
+const patterns = [
+  '**/*.html',
+  'atom.xml',
+  'feed.json',
+  'robots.txt',
+  'rss.xml',
+  'sitemap.xml',
+];
+const brotliCompress = promisify(zlib.brotliCompress);
+const gzip = promisify(zlib.gzip);
+
+async function compressSite() {
+  const files = await Globby(patterns.map((s) => path.join('build', s)));
+  const promises = files.map(async (file) => {
+    const contents = await readFile(file);
+    const maxLength = contents.length * minRatio;
+    const gzipContents = await gzip(contents, gzipOptions);
+    if (gzipContents.length <= maxLength) {
+      await writeFile(`${file}.gz`, gzipContents);
+    }
+    const brotliContents = await brotliCompress(contents, brotliOptions);
+    if (brotliContents.length <= maxLength) {
+      await writeFile(`${file}.br`, brotliContents);
+    }
+  });
+  await Promise.all(promises);
+}
+
+// @ts-expect-error This file is run directly by nodejs, so top-level await is fine here.
+await compressSite();
diff --git a/scripts/compressionOptions.mjs b/scripts/compressionOptions.mjs
new file mode 100644
index 0000000..3f2d226
--- /dev/null
+++ b/scripts/compressionOptions.mjs
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2024 Kristóf Marussy <kristof@marussy.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+import zlib from 'node:zlib';
+
+export const minRatio = 0.8;
+
+/** @type {import('node:zlib').ZlibOptions} */
+export const gzipOptions = {
+  level: 9,
+};
+
+/** @type {import('node:zlib').BrotliOptions} */
+export const brotliOptions = {
+  params: {
+    [zlib.constants.BROTLI_PARAM_QUALITY]: 11,
+  },
+};
diff --git a/src/plugins/compressionPlugin.ts b/src/plugins/compressionPlugin.ts
index 8b347cf..7b9feeb 100644
--- a/src/plugins/compressionPlugin.ts
+++ b/src/plugins/compressionPlugin.ts
@@ -4,35 +4,20 @@
  * SPDX-License-Identifier: MIT
  */
 
-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 { BrotliOptions } from 'node:zlib';
 
-import pluginSitemap, { type PluginOptions } from '@docusaurus/plugin-sitemap';
-import type { LoadContext, Plugin } from '@docusaurus/types';
-import { Globby } from '@docusaurus/utils';
+import type { Plugin } from '@docusaurus/types';
 import CompressionPlugin from 'compression-webpack-plugin';
 
-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'];
+import {
+  brotliOptions,
+  gzipOptions,
+  minRatio,
+} from '../../scripts/compressionOptions.mjs';
 
-const gzip = promisify(zlib.gzip);
-const brotliCompress = promisify(zlib.brotliCompress);
+const test = /\.(js|css|svg|txt)$/;
 
-export default function compressionPlugin(
-  context: LoadContext,
-  options: PluginOptions,
-): Plugin<void> {
-  const sitemap = pluginSitemap(context, options);
+export default function compressionPlugin(): Plugin<void> {
   return {
     name: 'marussy-compression-plugin',
     configureWebpack: (_config, isServer) =>
@@ -44,28 +29,16 @@ export default function compressionPlugin(
                 test,
                 filename: '[path][base].gz',
                 compressionOptions: gzipOptions,
+                minRatio,
               }),
               new CompressionPlugin<BrotliOptions>({
                 test,
                 filename: '[path][base].br',
                 algorithm: 'brotliCompress',
                 compressionOptions: brotliOptions,
+                minRatio,
               }),
             ],
           },
-    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';