From 76d2ab0eb9237cc0f0f863a5b0a500b9a5ad50b7 Mon Sep 17 00:00:00 2001
From: Owen Pearson <owen.pearson@ably.com>
Date: Wed, 19 Jul 2023 10:58:21 +0100
Subject: [PATCH] ci: display info about sizes of tree-shakable modules

---
 .github/workflows/bundle-report.yml |  1 +
 package.json                        |  1 +
 scripts/moduleReport.js             | 37 +++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)
 create mode 100644 scripts/moduleReport.js

diff --git a/.github/workflows/bundle-report.yml b/.github/workflows/bundle-report.yml
index 7866bb9dc3..39dda65d14 100644
--- a/.github/workflows/bundle-report.yml
+++ b/.github/workflows/bundle-report.yml
@@ -37,3 +37,4 @@ jobs:
           sourcePath: bundle-reports
           githubToken: ${{ secrets.GITHUB_TOKEN }}
           artifactName: bundle-report
+      - run: npm run modulereport
diff --git a/package.json b/package.json
index 4c62961d7d..a4efcb6679 100644
--- a/package.json
+++ b/package.json
@@ -96,6 +96,7 @@
     "format:check": "prettier --check --ignore-path .gitignore --ignore-path .prettierignore src test ably.d.ts webpack.config.js Gruntfile.js scripts/cdn_deploy.js",
     "sourcemap": "source-map-explorer build/ably.min.js",
     "sourcemap:noencryption": "source-map-explorer build/ably.noencryption.min.js",
+    "modulereport": "node scripts/moduleReport.js",
     "docs": "typedoc --entryPoints ably.d.ts --out docs/generated --readme docs/landing-page.md"
   }
 }
diff --git a/scripts/moduleReport.js b/scripts/moduleReport.js
new file mode 100644
index 0000000000..a1d8f70e68
--- /dev/null
+++ b/scripts/moduleReport.js
@@ -0,0 +1,37 @@
+const esbuild = require('esbuild');
+
+// List of all modules accepted in ModulesMap
+const moduleNames = ['Rest'];
+
+function formatBytes(bytes) {
+  const kb = bytes / 1024;
+  const formatted = kb.toFixed(2);
+  return `${formatted}kb`;
+}
+
+// Gets the bundled size of an array of named exports from 'ably/modules' formatted as a string
+function getImportSize(modules) {
+  const outfile = modules.join('');
+  const result = esbuild.buildSync({
+    stdin: {
+      contents: `export { ${modules.join(', ')} } from './build/modules'`,
+      resolveDir: '.',
+    },
+    metafile: true,
+    minify: true,
+    bundle: true,
+    outfile,
+    write: false,
+  });
+
+  return formatBytes(result.metafile.outputs[outfile].bytes);
+}
+
+// First display the size of the BaseClient
+console.log(`BaseClient: ${getImportSize(['BaseClient'])}`);
+
+// Then display the size of each module together with the BaseClient
+moduleNames.forEach((moduleName) => {
+  const sizeInBytes = getImportSize(['BaseClient', moduleName]);
+  console.log(`BaseClient + ${moduleName}: ${sizeInBytes}`);
+});