Internationalization #

# pubspec.yaml
dependencies:
  flutter_localizations:
    sdk: flutter
  intl: ^0.20.1          # format tanggal, angka, pluralisasi

flutter:
  generate: true         # aktifkan code generation dari ARB

# Opsional: path ARB kustom (default: lib/l10n)

# l10n.yaml -- konfigurasi code generation
arb-dir: lib/l10n
template-arb-file: app_id.arb     # bahasa default (template)
output-localization-file: app_localizations.dart
output-class: AppLocalizations
# untranslated-messages-file: untranslated_messages.txt  # log terjemahan yang hilang

// lib/l10n/app_id.arb -- TEMPLATE (Bahasa Indonesia, bahasa default)
{
  "@@locale": "id",

  "appTitle": "Toko Saya",
  "@appTitle": {
    "description": "Nama aplikasi"
  },

  "welcomeMessage": "Selamat datang, {name}!",
  "@welcomeMessage": {
    "description": "Pesan sambutan pengguna",
    "placeholders": {
      "name": {
        "type": "String",
        "example": "Budi"
      }
    }
  },

  "itemCount": "{count, plural, =0{Tidak ada item} =1{1 item} other{{count} item}}",
  "@itemCount": {
    "description": "Jumlah item dengan pluralisasi",
    "placeholders": {
      "count": {
        "type": "num",
        "format": "compact"
      }
    }
  },

  "harga": "Rp {amount}",
  "@harga": {
    "description": "Format harga",
    "placeholders": {
      "amount": {
        "type": "double",
        "format": "decimalPattern",
        "optionalParameters": {
          "decimalDigits": 0
        }
      }
    }
  },

  "loginButton": "Masuk",
  "@loginButton": { "description": "Teks tombol login" },

  "errorNetwork": "Tidak ada koneksi internet. Periksa jaringan kamu.",
  "@errorNetwork": { "description": "Pesan error jaringan" },

  "lastUpdated": "Diperbarui: {date}",
  "@lastUpdated": {
    "description": "Waktu terakhir diperbarui",
    "placeholders": {
      "date": {
        "type": "DateTime",
        "format": "yMMMd"
      }
    }
  }
}

// lib/l10n/app_en.arb -- Terjemahan Inggris
{
  "@@locale": "en",
  "appTitle": "My Store",
  "welcomeMessage": "Welcome, {name}!",
  "itemCount": "{count, plural, =0{No items} =1{1 item} other{{count} items}}",
  "harga": "IDR {amount}",
  "loginButton": "Sign In",
  "errorNetwork": "No internet connection. Check your network.",
  "lastUpdated": "Updated: {date}"
}

// lib/l10n/app_ar.arb -- Terjemahan Arab (RTL)
{
  "@@locale": "ar",
  "appTitle": "متجري",
  "welcomeMessage": "مرحباً، {name}!",
  "itemCount": "{count, plural, =0{لا توجد عناصر} =1{عنصر واحد} two{عنصران} few{{count} عناصر} other{{count} عنصر}}",
  "loginButton": "تسجيل الدخول",
  "errorNetwork": "لا يوجد اتصال بالإنترنت. تحقق من شبكتك."
}

# Generate kode dari file ARB
flutter gen-l10n
# atau otomatis saat flutter run / flutter build

// main.dart
import 'package:flutter_localizations/flutter_localizations.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';

class MyApp extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final locale = ref.watch(localeProvider);  // bahasa aktif dari provider

    return MaterialApp(
      // Konfigurasi lokalisasi
      localizationsDelegates: const [
        AppLocalizations.delegate,              // delegate generated kita
        GlobalMaterialLocalizations.delegate,   // Material widget (DatePicker, dll)
        GlobalWidgetsLocalizations.delegate,    // widget dasar (teks arah)
        GlobalCupertinoLocalizations.delegate,  // Cupertino widget
      ],
      supportedLocales: const [
        Locale('id'),  // Bahasa Indonesia
        Locale('en'),  // English
        Locale('ar'),  // Arabic
        Locale('zh'),  // Chinese (Simplified)
      ],
      locale: locale,  // null = ikuti bahasa device

      // Fallback jika bahasa device tidak didukung
      localeResolutionCallback: (deviceLocale, supportedLocales) {
        if (deviceLocale == null) return const Locale('id');

        // Cari locale yang cocok
        for (final supported in supportedLocales) {
          if (supported.languageCode == deviceLocale.languageCode) {
            return supported;
          }
        }

        // Default ke Indonesia jika tidak ada yang cocok
        return const Locale('id');
      },

      home: const HomeScreen(),
    );
  }
}

// Setelah generate, gunakan AppLocalizations.of(context)
class HomeScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;  // shortcut

    return Scaffold(
      appBar: AppBar(title: Text(l10n.appTitle)),
      body: Column(
        children: [
          // String sederhana
          Text(l10n.loginButton),

          // String dengan placeholder
          Text(l10n.welcomeMessage('Budi')),

          // Pluralisasi -- otomatis memilih bentuk yang tepat
          Text(l10n.itemCount(0)),   // "Tidak ada item"
          Text(l10n.itemCount(1)),   // "1 item"
          Text(l10n.itemCount(42)), // "42 item"

          // Format harga
          Text(l10n.harga(150000)),  // "Rp 150.000"

          // Format tanggal
          Text(l10n.lastUpdated(DateTime.now())),  // "Diperbarui: 15 Jan 2025"
        ],
      ),
    );
  }
}

// Extension untuk akses lebih pendek
extension AppLocalizationsX on BuildContext {
  AppLocalizations get l10n => AppLocalizations.of(this)!;
}

// Penggunaan dengan extension
Text(context.l10n.appTitle)
Text(context.l10n.welcomeMessage('Budi'))

// lib/core/providers/locale_provider.dart
final localeProvider = NotifierProvider<LocaleNotifier, Locale?>(
  LocaleNotifier.new,
);

class LocaleNotifier extends Notifier<Locale?> {
  @override
  Locale? build() {
    // Baca bahasa tersimpan dari SharedPreferences
    final prefs = ref.watch(appPreferencesProvider);
    final saved = prefs.bahasa;
    if (saved == null) return null;  // null = ikuti device
    return Locale(saved);
  }

  Future<void> setLocale(String languageCode) async {
    final prefs = ref.read(appPreferencesProvider);
    await prefs.setBahasa(languageCode);
    state = Locale(languageCode);
  }

  Future<void> resetToDevice() async {
    final prefs = ref.read(appPreferencesProvider);
    await prefs.setBahasa(null);
    state = null;
  }
}

// Widget pemilih bahasa
class LanguageSelectorWidget extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final currentLocale = ref.watch(localeProvider);

    return DropdownButton<String>(
      value: currentLocale?.languageCode ?? 'id',
      items: const [
        DropdownMenuItem(value: 'id', child: Text('🇮🇩 Bahasa Indonesia')),
        DropdownMenuItem(value: 'en', child: Text('🇬🇧 English')),
        DropdownMenuItem(value: 'ar', child: Text('🇸🇦 العربية')),
      ],
      onChanged: (code) {
        if (code != null) {
          ref.read(localeProvider.notifier).setLocale(code);
        }
      },
    );
  }
}

// Flutter otomatis membalik layout untuk RTL
// Tapi perlu pastikan widget kamu RTL-aware:

// AMAN: gunakan Start/End alih-alih Left/Right
Padding(
  padding: const EdgeInsets.only(
    start: 16,  // kiri di LTR, kanan di RTL
    end: 8,     // kanan di LTR, kiri di RTL
  ),
  child: text,
)

// Row dengan MainAxisAlignment -- otomatis dibalik
Row(
  children: [
    const Icon(Icons.arrow_back),  // menjadi arrow_forward di RTL!
    // Gunakan Icons.arrow_back_ios_new yang aware RTL
    // atau tentukan secara eksplisit:
  ],
)

// Gunakan Directionality.of(context) untuk cek arah saat ini
final isRTL = Directionality.of(context) == TextDirection.rtl;

// Atau paksa RTL untuk widget tertentu
Directionality(
  textDirection: TextDirection.rtl,
  child: MyWidget(),
)

// Icons yang RTL-aware
Icon(Icons.arrow_back)  // otomatis dibalik di RTL
// Gunakan: Icons.arrow_back_ios vs Icons.arrow_forward_ios sesuai konteks

import 'package:intl/intl.dart';

class FormatHelper {
  // Format angka sesuai locale
  static String formatAngka(double angka, String locale) {
    return NumberFormat.decimalPattern(locale).format(angka);
    // id: 1.234.567,89
    // en: 1,234,567.89
  }

  // Format mata uang
  static String formatMataUang(double angka, {String currency = 'IDR', String locale = 'id'}) {
    return NumberFormat.currency(
      locale: locale,
      symbol: currency == 'IDR' ? 'Rp ' : '\$',
      decimalDigits: currency == 'IDR' ? 0 : 2,
    ).format(angka);
    // IDR: Rp 150.000
    // USD: $1,500.00
  }

  // Format tanggal
  static String formatTanggal(DateTime tanggal, String locale) {
    return DateFormat.yMMMMd(locale).format(tanggal);
    // id: 15 Januari 2025
    // en: January 15, 2025
    // ar: ١٥ يناير ٢٠٢٥
  }

  // Format relatif (X menit lalu, kemarin, dll.)
  static String formatRelatif(DateTime tanggal, BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    final selisih = DateTime.now().difference(tanggal);

    if (selisih.inMinutes < 1) return l10n.justNow;
    if (selisih.inHours < 1) return l10n.minutesAgo(selisih.inMinutes);
    if (selisih.inDays < 1) return l10n.hoursAgo(selisih.inHours);
    if (selisih.inDays < 7) return l10n.daysAgo(selisih.inDays);
    return formatTanggal(tanggal, Localizations.localeOf(context).languageCode);
  }
}