feat(per-app-language): add Android config plugin

packages/react-native-android-per-app-language/.eslintrc.js

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+// @generated by expo-module-scripts
+module.exports = require('expo-module-scripts/eslintrc.base.js');

packages/react-native-android-per-app-language/CHANGELOG.md

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+### @config-plugins/react-native-android-per-app-language 1.0.0
+
+- 
+### Added
+- Initial release of the `@config-plugins/react-native-android-per-app-language` plugin.
+- Implemented support for Android's per-app language preferences feature.
+- Added functionality to modify the Android Manifest to include the `localeConfig` attribute.
+- Created a config plugin to generate the `locales_config.xml` file with user-specified supported languages.

packages/react-native-android-per-app-language/README.md

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+# @config-plugins/react-native-android-per-app-language
+
+### How it works
+This plugin automates the manual setup process described in the [Android documentation](https://developer.android.com/guide/topics/resources/app-languages#use-localeconfig) for implementing per-app language preferences:
+
+1. Modifies the `AndroidManifest.xml` to add the `android:localeConfig` attribute to the `<application>` tag.
+2. Creates a `res/xml/locales_config.xml` file with the specified supported languages.
+
+## Expo installation
+To use this plugin in your Expo project, follow these steps:
+
+1. Install the plugin:
+   ```
+   expo install @config-plugins/react-native-android-per-app-language
+   ```
+
+2. Add the plugin to your `app.json` or `app.config.js`:
+   ```json
+   {
+     "expo": {
+       "plugins": [
+         [
+           "@config-plugins/react-native-android-per-app-language",
+           {
+             "supportedLanguages": ["en", "es", "fr"]
+           }
+         ]
+       ]
+     }
+   }
+   ```
+
+   The `supportedLanguages` parameter is required and should be an array of language codes that your app supports.
+
+3. Rebuild your app:
+   ```
+   expo prebuild
+   ```
+
+This will configure your Android project to support per-app language preferences for the specified languages.
+

packages/react-native-android-per-app-language/app.plugin.js

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+module.exports = require("./build/withAndroidPerAppLanguage");

packages/react-native-android-per-app-language/jest.config.js

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+module.exports = require('expo-module-scripts/jest-preset-plugin');

packages/react-native-android-per-app-language/package.json

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+{
+  "name": "@config-plugins/react-native-android-per-app-language",
+  "version": "8.0.0",
+  "description": "Config plugin to auto configure react-native-android-per-app-language on prebuild",
+  "main": "build/withAndroidPerAppLanguage.js",
+  "types": "build/withAndroidPerAppLanguage.d.ts",
+  "sideEffects": false,
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/expo/config-plugins.git",
+    "directory": "packages/react-native-android-per-app-language"
+  },
+  "files": [
+    "build",
+    "app.plugin.js"
+  ],
+  "scripts": {
+    "build": "expo-module build",
+    "clean": "expo-module clean",
+    "lint": "expo-module lint",
+    "test": "expo-module test",
+    "prepare": "expo-module prepare",
+    "prepublishOnly": "expo-module prepublishOnly",
+    "expo-module": "expo-module"
+  },
+  "keywords": [
+    "android",
+    "localization",
+    "react-native-android-per-app-language",
+    "react-native",
+    "expo"
+  ],
+  "peerDependencies": {
+    "expo": "^51"
+  },
+  "devDependencies": {
+    "expo-module-scripts": "^3.5.1"
+  },
+  "upstreamPackage": "react-native-android-per-app-language"
+}

packages/react-native-android-per-app-language/src/__tests__/__snapshots__/withAndroidPerAppLanguage.test.ts.snap

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+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`getTemplateFile returns only base-config when subdomains is '*' 1`] = `
+"<?xml version="1.0" encoding="utf-8"?>
+<locale-config xmlns:android="http://schemas.android.com/apk/res/android">
+   <locale android:name="en"/>
+</locale-config>"
+`;

packages/react-native-android-per-app-language/src/__tests__/withAndroidPerAppLanguage.test.ts

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+import { getTemplateFile } from "../withAndroidPerAppLanguage";
+
+describe("getTemplateFile", () => {
+  it("returns the expected XML content", () => {
+    const supportedLanguages = ["en", "fr"];
+    const expectedContent = `<?xml version="1.0" encoding="utf-8"?>
+<locale-config xmlns:android="http://schemas.android.com/apk/res/android">
+   <locale android:name="en"/>
+   <locale android:name="fr"/>
+</locale-config>`;
+    const content = getTemplateFile(supportedLanguages);
+    expect(content).toEqual(expectedContent);
+  });
+});

packages/react-native-android-per-app-language/src/withAndroidPerAppLanguage.ts

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+import {
+  ConfigPlugin,
+  withAndroidManifest,
+  AndroidManifest,
+  withDangerousMod,
+  AndroidConfig,
+} from "expo/config-plugins";
+import * as fs from "fs";
+import * as path from "path";
+
+type SupportedLanguages = string[];
+
+export const withAndroidPerAppLanguage: ConfigPlugin<{
+  supportedLanguages: SupportedLanguages;
+}> = (config, { supportedLanguages }) => {
+  if (!supportedLanguages || !supportedLanguages.length) {
+    return config;
+  }
+
+  /**
+   * Modify the Android Manifest 'application' to include the localeConfig attribute
+   */
+  config = withAndroidManifest(config, (config) => {
+    config.modResults = addLocaleConfigToManifest(config.modResults);
+    return config;
+  });
+
+  /**
+   * Create `network_security_config.xml` resource file.
+   */
+  return withDangerousMod(config, [
+    "android",
+    async (config) => {
+      const folder = path.join(
+        config.modRequest.platformProjectRoot,
+        `app/src/main/res/xml`,
+      );
+      fs.mkdirSync(folder, { recursive: true });
+      fs.writeFileSync(
+        path.join(folder, "locales_config.xml"),
+        getTemplateFile(supportedLanguages),
+        { encoding: "utf8" },
+      );
+      return config;
+    },
+  ]);
+};
+
+export const addLocaleConfigToManifest = (androidManifest: AndroidManifest) => {
+  const application =
+    AndroidConfig.Manifest.getMainApplicationOrThrow(androidManifest);
+
+  application.$["android:localeConfig"] = "@xml/locales_config";
+  return androidManifest;
+};
+
+export const getTemplateFile = (supportedLanguages: SupportedLanguages) => {
+  const localesList = supportedLanguages
+    .map((lang) => `   <locale android:name="${lang}"/>`)
+    .join("\n");
+
+  const content = `<?xml version="1.0" encoding="utf-8"?>
+<locale-config xmlns:android="http://schemas.android.com/apk/res/android">
+${localesList}
+</locale-config>`;
+  return content;
+};

packages/react-native-android-per-app-language/tsconfig.json

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+{
+  "extends": "expo-module-scripts/tsconfig.plugin",
+  "compilerOptions": {
+    "outDir": "build",
+    "rootDir": "src"
+  },
+  "include": ["./src"],
+  "exclude": ["**/__mocks__/*", "**/__tests__/*"]
+}