feat: i18n 개선 및 userfront 로그인/로케일 보완

userfront/lib/core/i18n/locale_gate.dart

@@ -0,0 +1,51 @@
+import 'package:easy_localization/easy_localization.dart' hide tr;
+import 'package:flutter/material.dart';
+
+import 'package:userfront/i18n.dart';
+import '../services/web_window.dart';
+import 'locale_storage.dart';
+import 'locale_utils.dart';
+
+class LocaleGate extends StatefulWidget {
+  const LocaleGate({super.key, required this.localeCode, required this.child});
+
+  final String localeCode;
+  final Widget child;
+
+  @override
+  State<LocaleGate> createState() => _LocaleGateState();
+}
+
+class _LocaleGateState extends State<LocaleGate> {
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    _applyLocale();
+  }
+
+  @override
+  void didUpdateWidget(LocaleGate oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (oldWidget.localeCode != widget.localeCode) {
+      _applyLocale();
+    }
+  }
+
+  Future<void> _applyLocale() async {
+    final normalized = normalizeLocaleCode(widget.localeCode);
+    LocaleStorage.write(normalized);
+    webWindow.setTitle(
+      tr('ui.userfront.app_title'),
+    );
+    if (context.locale.languageCode == normalized) {
+      return;
+    }
+    await context.setLocale(Locale(normalized));
+    webWindow.setTitle(
+      tr('ui.userfront.app_title'),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) => widget.child;
+}

userfront/lib/core/i18n/locale_storage.dart

@@ -0,0 +1,7 @@
+import 'locale_storage_stub.dart'
+    if (dart.library.html) 'locale_storage_web.dart';
+
+abstract class LocaleStorage {
+  static String? read() => localeStorage.read();
+  static void write(String locale) => localeStorage.write(locale);
+}

userfront/lib/core/i18n/locale_storage_stub.dart

@@ -0,0 +1,11 @@
+class LocaleStorageImpl {
+  String? _locale;
+
+  String? read() => _locale;
+
+  void write(String locale) {
+    _locale = locale;
+  }
+}
+
+final localeStorage = LocaleStorageImpl();

userfront/lib/core/i18n/locale_storage_web.dart

@@ -0,0 +1,120 @@
+// ignore_for_file: avoid_web_libraries_in_flutter
+
+import 'dart:html' as html;
+import 'package:flutter/foundation.dart';
+
+class LocaleStorageImpl {
+  static const _key = 'locale';
+  static const _legacyKey = 'baron_locale';
+  static final Map<String, String> _memory = {};
+  static bool _forceMemory = false;
+  static bool _forceSession = false;
+
+  @visibleForTesting
+  static void forceMemoryStorageForTests(bool value) {
+    _forceMemory = value;
+    if (!value) {
+      _memory.clear();
+    }
+  }
+
+  @visibleForTesting
+  static void forceSessionStorageForTests(bool value) {
+    _forceSession = value;
+  }
+
+  String? _read(String key) {
+    if (!_forceMemory && !_forceSession) {
+      try {
+        return html.window.localStorage[key];
+      } catch (_) {
+        // localStorage 접근이 차단된 경우 sessionStorage로 fallback.
+        try {
+          return html.window.sessionStorage[key];
+        } catch (_) {
+          // sessionStorage도 차단된 경우 메모리 fallback 사용.
+        }
+      }
+    }
+    if (!_forceMemory) {
+      try {
+        return html.window.sessionStorage[key];
+      } catch (_) {
+        // sessionStorage도 차단된 경우 메모리 fallback 사용.
+      }
+    }
+    return _memory[key];
+  }
+
+  void _write(String key, String value) {
+    if (!_forceMemory && !_forceSession) {
+      try {
+        html.window.localStorage[key] = value;
+        return;
+      } catch (_) {
+        // localStorage 접근이 차단된 경우 sessionStorage로 fallback.
+        try {
+          html.window.sessionStorage[key] = value;
+          return;
+        } catch (_) {
+          // sessionStorage도 차단된 경우 메모리 fallback 사용.
+        }
+      }
+    }
+    if (!_forceMemory) {
+      try {
+        html.window.sessionStorage[key] = value;
+        return;
+      } catch (_) {
+        // sessionStorage도 차단된 경우 메모리 fallback 사용.
+      }
+    }
+    _memory[key] = value;
+  }
+
+  void _remove(String key) {
+    if (!_forceMemory && !_forceSession) {
+      try {
+        html.window.localStorage.remove(key);
+        return;
+      } catch (_) {
+        // localStorage 접근이 차단된 경우 sessionStorage로 fallback.
+        try {
+          html.window.sessionStorage.remove(key);
+          return;
+        } catch (_) {
+          // sessionStorage도 차단된 경우 메모리 fallback 사용.
+        }
+      }
+    }
+    if (!_forceMemory) {
+      try {
+        html.window.sessionStorage.remove(key);
+        return;
+      } catch (_) {
+        // sessionStorage도 차단된 경우 메모리 fallback 사용.
+      }
+    }
+    _memory.remove(key);
+  }
+
+  String? read() {
+    final current = _read(_key);
+    if (current != null && current.isNotEmpty) {
+      return current;
+    }
+    final legacy = _read(_legacyKey);
+    if (legacy != null && legacy.isNotEmpty) {
+      _write(_key, legacy);
+      _remove(_legacyKey);
+      return legacy;
+    }
+    return null;
+  }
+
+  void write(String locale) {
+    _write(_key, locale);
+  }
+}
+
+final localeStorage = LocaleStorageImpl();

userfront/lib/core/i18n/locale_utils.dart

@@ -0,0 +1,69 @@
+import 'dart:ui';
+
+import 'locale_storage.dart';
+
+const supportedLocaleCodes = ['en', 'ko'];
+const defaultLocaleCode = 'en';
+
+String normalizeLocaleCode(String? code) {
+  if (code == null || code.isEmpty) {
+    return defaultLocaleCode;
+  }
+  final normalized = code.toLowerCase();
+  if (normalized == 'ko' || normalized.startsWith('ko-')) {
+    return 'ko';
+  }
+  if (normalized == 'en' || normalized.startsWith('en-')) {
+    return 'en';
+  }
+  return defaultLocaleCode;
+}
+
+String resolvePreferredLocaleCode() {
+  final stored = LocaleStorage.read();
+  if (stored != null && supportedLocaleCodes.contains(stored)) {
+    return stored;
+  }
+  final deviceLocale = PlatformDispatcher.instance.locale;
+  return normalizeLocaleCode(deviceLocale.languageCode);
+}
+
+String? extractLocaleFromPath(Uri uri) {
+  if (uri.pathSegments.isEmpty) {
+    return null;
+  }
+  final code = uri.pathSegments.first.toLowerCase();
+  if (supportedLocaleCodes.contains(code)) {
+    return code;
+  }
+  return null;
+}
+
+String stripLocalePath(Uri uri) {
+  final segments = uri.pathSegments;
+  if (segments.isNotEmpty && supportedLocaleCodes.contains(segments.first)) {
+    final rest = segments.skip(1).join('/');
+    if (rest.isEmpty) {
+      return '/';
+    }
+    return '/$rest';
+  }
+  return uri.path;
+}
+
+String buildLocalizedPath(String localeCode, Uri uri) {
+  final segments = uri.pathSegments;
+  Iterable<String> restSegments = segments;
+  if (segments.isNotEmpty) {
+    final head = segments.first.toLowerCase();
+    if (supportedLocaleCodes.contains(head) || head.length == 2) {
+      restSegments = segments.skip(1);
+    }
+  }
+  final newSegments = [localeCode, ...restSegments];
+  final path = '/${newSegments.join('/')}';
+  if (uri.queryParameters.isEmpty) {
+    return path;
+  }
+  return Uri(path: path, queryParameters: uri.queryParameters).toString();
+}

userfront/lib/core/i18n/toml_asset_loader.dart

@@ -0,0 +1,22 @@
+import 'dart:ui';
+
+import 'package:easy_localization/easy_localization.dart';
+import 'package:flutter/services.dart';
+import 'package:toml/toml.dart';
+
+class TomlAssetLoader extends AssetLoader {
+  const TomlAssetLoader();
+
+  @override
+  Future<Map<String, dynamic>> load(String path, Locale locale) async {
+    final assetPath = '$path/${locale.languageCode}.toml';
+    try {
+      final content = await rootBundle.loadString(assetPath);
+      final document = TomlDocument.parse(content);
+      return document.toMap();
+    } catch (e) {
+      // 로딩 실패 시 빈 맵을 반환해 렌더링을 지속합니다.
+      return {};
+    }
+  }
+}