Copy missing locale paks on build

ts/scripts/after-pack.ts

@@ -1,11 +1,13 @@
-// Copyright 2021 Signal Messenger, LLC
+// Copyright 2021-2022 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
 import type { AfterPackContext } from 'electron-builder';
 import { afterPack as fuseElectron } from './fuse-electron';
 import { afterPack as mergeASARs } from './merge-macos-asars';
+import { afterPack as copyPacks } from './copy-language-packs';
 
 export async function afterPack(context: AfterPackContext): Promise<void> {
   await mergeASARs(context);
   await fuseElectron(context);
+  await copyPacks(context);
 }

ts/scripts/copy-language-packs.ts

@@ -0,0 +1,74 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import fse from 'fs-extra';
+import path from 'path';
+import type { AfterPackContext } from 'electron-builder';
+
+export async function afterPack({
+  appOutDir,
+  packager,
+  electronPlatformName,
+}: AfterPackContext): Promise<void> {
+  let defaultLocale: string;
+  let ourLocales = await fse.readdir(
+    path.join(__dirname, '..', '..', '_locales')
+  );
+
+  let localesPath: string;
+  if (electronPlatformName === 'darwin') {
+    const { productFilename } = packager.appInfo;
+
+    // en.lproj/locale.pak
+    // zh_CN.lproj/locale.pak
+    defaultLocale = 'en.lproj';
+    ourLocales = ourLocales.map(locale => `${locale}.lproj`);
+
+    localesPath = path.join(
+      appOutDir,
+      `${productFilename}.app`,
+      'Contents',
+      'Frameworks',
+      'Electron Framework.framework',
+      'Resources'
+    );
+  } else if (
+    electronPlatformName === 'linux' ||
+    electronPlatformName === 'win32'
+  ) {
+    // Shared between windows and linux
+    defaultLocale = 'en-US.pak';
+    ourLocales = ourLocales.map(locale => {
+      if (locale === 'en') {
+        return defaultLocale;
+      }
+
+      return `${locale.replace(/_/g, '-')}.pak`;
+    });
+
+    localesPath = path.join(appOutDir, 'locales');
+  } else {
+    console.error(
+      `Unsupported platform: ${electronPlatformName}, not copying pak files`
+    );
+    return;
+  }
+
+  const electronLocales = new Set(await fse.readdir(localesPath));
+  const promises = new Array<Promise<void>>();
+  for (const locale of ourLocales) {
+    if (electronLocales.has(locale)) {
+      continue;
+    }
+
+    console.log(`Copying ${defaultLocale} to ${locale}`);
+    promises.push(
+      fse.copy(
+        path.join(localesPath, defaultLocale),
+        path.join(localesPath, locale)
+      )
+    );
+  }
+
+  await Promise.all(promises);
+}