feat(ui): generate labels from .arb (#9340)

packages/firebase_ui_localizations/.gitignore

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+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+# Libraries should not include pubspec.lock, per https://dart.dev/guides/libraries/private-files#pubspeclock.
+/pubspec.lock
+**/doc/api/
+.dart_tool/
+.packages
+build/

packages/firebase_ui_localizations/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: f1875d570e39de09040c8f79aa13cc56baab8db1
+  channel: stable
+
+project_type: package

packages/firebase_ui_localizations/CHANGELOG.md

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+## 1.0.0-dev.0
+
+ - Bump "firebase_ui_localizations" to `1.0.0-dev.0`.
+
+## 0.0.1
+
+* TODO: Describe initial release.

packages/firebase_ui_localizations/LICENSE

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+Copyright 2017, the Chromium project authors. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google Inc. nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

packages/firebase_ui_localizations/README.md

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+# Localization
+
+Firebase UI for Flutter supports localization, so every single label can be customized.
+
+## Installation
+
+```yaml
+dependencies:
+  flutter_localizations:
+    sdk: flutter
+  firebase_ui_localizations: ^1.0.0
+```
+
+## Usage
+
+If your app supports only a single language, and you want to override labels – you will need to provide a custom class that implements [`DefaultLocalizations`](https://pub.dev/documentation/firebase_ui_localizations/latest/DefaultLocalizations-class.html),
+for example:
+
+```dart
+import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:firebase_ui_localizations/firebase_ui_localizations.dart';
+
+class LabelOverrides extends DefaultLocalizations {
+  const LabelOverrides();
+
+  @override
+  String get emailInputLabel => 'Enter your email';
+
+  @override
+  String get passwordInputLabel => 'Enter your password';
+}
+```
+
+Once created, pass the instance of `LabelOverrides` to the `localizationsDelegates` list in your `MaterialApp`/`CupertinoApp`:
+
+```dart
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      localizationsDelegates: [
+        // Creates an instance of FirebaseUILocalizationDelegate with overridden labels
+        FirebaseUILocalizations.withDefaultOverrides(const LabelOverrides()),
+
+        // Delegates below take care of built-in flutter widgets
+        GlobalMaterialLocalizations.delegate,
+        GlobalWidgetsLocalizations.delegate,
+
+        // This delegate is required to provide the labels that are not overridden by LabelOverrides
+        FirebaseUILocalizations.delegate,
+      ],
+      // ...
+    );
+  }
+}
+```
+
+If you need to support multiple languages – follow the [official Flutter localization guide](https://docs.flutter.dev/development/accessibility-and-localization/internationalization#an-alternative-class-for-the-apps-localized-resources)
+and make sure that your custom delegate extends `LocalizationsDelegate<FirebaseUILocalizations>`.
+
+> Note: check out [API reference](https://pub.dev/documentation/firebase_ui_localizations/latest/FlutterFireUILocalizationLabels-class.html) to learn what labels are used by specific widgets

packages/firebase_ui_localizations/analysis_options.yaml

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+include: package:flutter_lints/flutter.yaml
+
+# Additional information about this file can be found at
+# https://dart.dev/guides/language/analysis-options

packages/firebase_ui_localizations/bin/gen_l10n.dart

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+import 'dart:convert';
+import 'dart:io';
+import 'package:path/path.dart' as path;
+
+late String cwd;
+late Directory outDir;
+
+void main() async {
+  cwd = Directory.current.path;
+  final l10nSrc = Directory(path.join(cwd, 'lib', 'l10n'));
+  outDir = Directory(path.join(cwd, 'lib', 'src'));
+
+  if (!outDir.existsSync()) {
+    outDir.createSync(recursive: true);
+  }
+
+  final readFutures = await l10nSrc.list().map((event) {
+    final file = File(event.path);
+    return file.openRead().transform(const Utf8Decoder()).toList();
+  }).toList();
+
+  final sources = await Future.wait(readFutures);
+
+  final labelsByLocale = sources.fold<Map<String, dynamic>>({}, (acc, lines) {
+    final fullSrc = lines.join();
+    final arbJson = jsonDecode(fullSrc);
+    final localeString = arbJson['@@locale'];
+
+    final parsed = localeString.split('_');
+
+    return {
+      ...acc,
+      parsed[0]: {
+        ...(acc[parsed[0]] ?? {}),
+        if (parsed.length > 1) parsed[1]: arbJson else 'default': arbJson,
+      }
+    };
+  });
+
+  final genOps = labelsByLocale.entries.map((entry) {
+    if (entry.value.length == 1) {
+      return [
+        generateLocalizationsClass(
+          locale: entry.key,
+          arb: entry.value['default'],
+        )
+      ];
+    }
+
+    return [
+      generateLocalizationsClass(
+        locale: entry.key,
+        arb: entry.value['default'],
+      ),
+      ...entry.value.entries
+          .where((element) => element.key != 'default')
+          .map((e) {
+        return generateLocalizationsClass(
+          locale: entry.key,
+          countryCode: e.key,
+          arb: e.value,
+        );
+      }).toList(),
+    ];
+  }).expand((element) => element);
+
+  await Future.wait([...genOps.cast<Future>()]);
+  await generateLanguagesList(labelsByLocale);
+  Process.runSync('dart', ['format', outDir.path]);
+}
+
+bool isLabelEntry(MapEntry<String, dynamic> entry) {
+  return !entry.key.startsWith('@');
+}
+
+String dartFilename(String locale, [String? countryCode]) {
+  return '$locale'
+      '${countryCode != null ? '_${countryCode.toLowerCase()}' : ''}'
+      '.dart';
+}
+
+String dartClassName(String locale, [String? countryCode]) {
+  return '${locale.capitalize()}'
+      '${countryCode?.capitalize() ?? ''}Localizations';
+}
+
+Future<void> generateLocalizationsClass({
+  required String locale,
+  required Map<String, dynamic> arb,
+  String? countryCode,
+}) async {
+  final filename = dartFilename(locale, countryCode);
+  final outFile = File(path.join(outDir.path, 'lang', filename));
+
+  if (!outFile.existsSync()) {
+    outFile.createSync(recursive: true);
+  }
+
+  final out = outFile.openWrite();
+
+  out.writeln("import '../default_localizations.dart';");
+
+  final labels = arb.entries.where(isLabelEntry).map((e) {
+    final meta = arb['@${e.key}'] ?? {};
+
+    return Label(
+      key: e.key,
+      translation: e.value,
+      description: meta['description'],
+    );
+  }).toList();
+
+  out.writeln();
+
+  final className = dartClassName(locale, countryCode);
+
+  out.writeln('class $className extends FirebaseUILocalizationLabels {');
+  out.writeln('  const $className();');
+
+  for (var label in labels) {
+    final escapedTranslation = jsonEncode(label.translation);
+
+    out.writeln();
+    out.writeln('  @override');
+    out.writeln('  String get ${label.key} => $escapedTranslation;');
+  }
+
+  out.writeln('}');
+
+  await out.flush();
+  await out.close();
+}
+
+Future<void> generateLanguagesList(Map<String, dynamic> arb) async {
+  final outFile = File(path.join(outDir.path, 'all_languages.dart'));
+
+  if (!outFile.existsSync()) {
+    outFile.createSync(recursive: true);
+  }
+
+  final out = outFile.openWrite();
+  out.writeln('import "./default_localizations.dart";');
+  out.writeln();
+
+  for (var entry in arb.entries) {
+    final locale = entry.key;
+    final countryCodes = entry.value.keys.where((e) => e != 'default').toList();
+
+    final filename = dartFilename(locale);
+    out.writeln("import 'lang/$filename';");
+
+    for (var countryCode in countryCodes) {
+      out.writeln("import 'lang/${dartFilename(locale, countryCode)}';");
+    }
+  }
+
+  out.writeln();
+  out.writeln('final localizations = <String, FirebaseUILocalizationLabels>{');
+
+  for (var entry in arb.entries) {
+    final locale = entry.key;
+    final countryCodes = entry.value.keys.where((e) => e != 'default').toList();
+
+    out.writeln("  '$locale': const ${dartClassName(locale)}(),");
+
+    for (var countryCode in countryCodes) {
+      final key = '${locale}_${countryCode.toLowerCase()}';
+      out.writeln("  '$key': const ${dartClassName(locale, countryCode)}(),");
+    }
+  }
+
+  out.writeln('};');
+
+  await out.flush();
+  await out.close();
+}
+
+extension StringExtension on String {
+  String capitalize() {
+    return "${this[0].toUpperCase()}${substring(1)}";
+  }
+}
+
+class Label {
+  final String key;
+  final String translation;
+  final String? description;
+
+  Label({
+    required this.key,
+    required this.translation,
+    this.description,
+  });
+}

packages/firebase_ui_localizations/lib/firebase_ui_localizations.dart

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+export 'src/l10n.dart'
+    show FirebaseUILocalizations, FirebaseUILocalizationDelegate;
+
+export 'src/default_localizations.dart'
+    show DefaultLocalizations, FirebaseUILocalizationLabels;