pubspec.yaml

name: cidr
description: "CIDR"
# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number is used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
# In Windows, build-name is used as the major, minor, and patch parts
# of the product and file versions while build-number is used as the build suffix.
version: 2.0.0+19

environment:
  sdk: ">=3.3.0 <4.0.0"

# Dependencies specify other packages that your package needs in order to work.
# To automatically upgrade your package dependencies to the latest versions
# consider running `flutter pub upgrade --major-versions`. Alternatively,
# dependencies can be manually updated by changing the version numbers below to
# the latest version available on pub.dev. To see which dependencies have newer
# versions available, run `flutter pub outdated`.
dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.8
  google_mobile_ads: ^6.0.0
  shared_preferences: ^2.2.3
  intl: ^0.20.2

dev_dependencies:
  flutter_test:
    sdk: flutter

  flutter_launcher_icons: ^0.14.3    #flutter pub run flutter_launcher_icons
  flutter_native_splash: ^2.3.6     #flutter pub run flutter_native_splash:create

  # The "flutter_lints" package below contains a set of recommended lints to
  # encourage good coding practices. The lint set provided by the package is
  # activated in the `analysis_options.yaml` file located at the root of your
  # package. See that file for information about deactivating specific lint
  # rules and activating additional ones.
  flutter_lints: ^6.0.0

# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

flutter_icons:
  android: "launcher_icon"
  ios: true
  image_path: "assets/icon/icon.png"
  adaptive_icon_background: "assets/icon/icon_back.png"
  adaptive_icon_foreground: "assets/icon/icon_fore.png"

flutter_native_splash:
  color: '#9da9f5'
  image: 'assets/image/splash.png'
  color_dark: '#9da9f5'
  image_dark: 'assets/image/splash.png'
  fullscreen: true
  android_12:
    icon_background_color: '#9da9f5'
    image: 'assets/image/splash.png'
    icon_background_color_dark: '#9da9f5'
    image_dark: 'assets/image/splash.png'

# The following section is specific to Flutter packages.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  # assets:
  #   - images/a_dot_burr.jpeg
  #   - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/to/resolution-aware-images

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/to/asset-from-package

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/to/font-from-package

lib/ad_banner_widget.dart

import 'package:flutter/cupertino.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';

import 'package:roulettewheeleurope/ad_manager.dart';

class AdBannerWidget extends StatefulWidget {
  final AdManager adManager;
  const AdBannerWidget({super.key, required this.adManager});
  @override
  State<AdBannerWidget> createState() => _AdBannerWidgetState();
}

class _AdBannerWidgetState extends State<AdBannerWidget> {
  int _lastBannerWidthDp = 0;
  bool _isAdLoaded = false;
  bool _isLoading = false;
  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: LayoutBuilder(
        builder: (context, constraints) {
          final int width = constraints.maxWidth.isFinite ? constraints.maxWidth.truncate() : MediaQuery.of(context).size.width.truncate();
          final bannerAd = widget.adManager.bannerAd;
          if (width > 0) {
            WidgetsBinding.instance.addPostFrameCallback((_) {
              if (mounted) {
                final bannerAd = widget.adManager.bannerAd;
                final bool widthChanged = _lastBannerWidthDp != width;
                final bool sizeMismatch = bannerAd == null || bannerAd.size.width != width;
                if ((widthChanged || !_isAdLoaded || sizeMismatch) && !_isLoading) {
                  _lastBannerWidthDp = width;
                  setState(() { _isAdLoaded = false; _isLoading = true; });
                  widget.adManager.loadAdaptiveBannerAd(width, () {
                    if (mounted) {
                      setState(() { _isAdLoaded = true; _isLoading = false; });
                    }
                  });
                }
              }
            });
          }
          if (_isAdLoaded && bannerAd != null) {
            return Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                SizedBox(
                  width: bannerAd.size.width.toDouble(),
                  height: bannerAd.size.height.toDouble(),
                  child: AdWidget(ad: bannerAd),
                ),
              ],
            );
          } else {
            return const SizedBox.shrink();
          }
        },
      ),
    );
  }
}

lib/ad_manager.dart

import 'dart:async';
import 'dart:io' show Platform;
import 'dart:ui';
import 'package:google_mobile_ads/google_mobile_ads.dart';

class AdManager {
  // Test IDs
  // static const String _androidAdUnitId = "ca-app-pub-3940256099942544/6300978111";
  // static const String _iosAdUnitId     = "ca-app-pub-3940256099942544/2934735716";

  // Production IDs
  static const String _androidAdUnitId = "ca-app-pub-0/0";
  static const String _iosAdUnitId     = "ca-app-pub-0/0";

  static String get _adUnitId => Platform.isIOS ? _iosAdUnitId : _androidAdUnitId;

  BannerAd? _bannerAd;
  int _lastWidthPx = 0;
  VoidCallback? _onLoadedCb;
  Timer? _retryTimer;
  int _retryAttempt = 0;

  BannerAd? get bannerAd => _bannerAd;

  Future<void> loadAdaptiveBannerAd(int widthPx, VoidCallback onAdLoaded) async {
    _onLoadedCb = onAdLoaded;
    _lastWidthPx = widthPx;
    _retryAttempt = 0;
    _retryTimer?.cancel();
    _startLoad(widthPx);
  }

  Future<void> _startLoad(int widthPx) async {
    _bannerAd?.dispose();

    AnchoredAdaptiveBannerAdSize? adaptiveSize;
    try {
      adaptiveSize = await AdSize.getCurrentOrientationAnchoredAdaptiveBannerAdSize(widthPx);
    } catch (_) {
      adaptiveSize = null;
    }
    final AdSize size = adaptiveSize ?? AdSize.fullBanner;

    _bannerAd = BannerAd(
      adUnitId: _adUnitId,
      request: const AdRequest(),
      size: size,
      listener: BannerAdListener(
        onAdLoaded: (ad) {
          _retryTimer?.cancel();
          _retryAttempt = 0;
          final cb = _onLoadedCb;
          if (cb != null) {
            cb();
          }
        },
        onAdFailedToLoad: (ad, err) {
          ad.dispose();
          _scheduleRetry();
        },
      ),
    )..load();
  }

  void _scheduleRetry() {
    _retryTimer?.cancel();
    // Exponential backoff: 3s, 6s, 12s, max 30s
    _retryAttempt = (_retryAttempt + 1).clamp(1, 5);
    final seconds = _retryAttempt >= 4 ? 30 : (3 << (_retryAttempt - 1));
    _retryTimer = Timer(Duration(seconds: seconds), () {
      _startLoad(_lastWidthPx > 0 ? _lastWidthPx : 320);
    });
  }

  void dispose() {
    _bannerAd?.dispose();
    _retryTimer?.cancel();
  }

}

lib/cidr_calculator.dart

class CidrCalculationResult {
  CidrCalculationResult({
    required this.sanitizedIp,
    required this.ipParts,
    required this.networkParts,
    required this.broadcastParts,
    required this.maskParts,
    required this.prefix,
    required this.hostCount,
    required this.networkInt,
    required this.broadcastInt,
  });

  final String sanitizedIp;
  final List<int> ipParts;
  final List<int> networkParts;
  final List<int> broadcastParts;
  final List<int> maskParts;
  final int prefix;
  final int hostCount;
  final int networkInt;
  final int broadcastInt;
}

class CidrCalculator {
  static CidrCalculationResult calculate(String rawIp, int prefix) {
    final int normalizedPrefix = prefix.clamp(1, 32).toInt();
    final List<int> ipParts = _sanitizeIp(rawIp);
    final List<int> maskParts = maskFromPrefix(normalizedPrefix);
    final int ipInt = _ipToInt(ipParts);
    final int maskInt = _ipToInt(maskParts);
    final int wildcardInt = 0xFFFFFFFF ^ maskInt;
    final int networkInt = ipInt & maskInt;
    final int broadcastInt = networkInt | wildcardInt;
    final List<int> networkParts = _intToIp(networkInt);
    final List<int> broadcastParts = _intToIp(broadcastInt);
    final int hostCount = hostCountForPrefix(normalizedPrefix);
    return CidrCalculationResult(
      sanitizedIp: formatIp(ipParts),
      ipParts: ipParts,
      networkParts: networkParts,
      broadcastParts: broadcastParts,
      maskParts: maskParts,
      prefix: normalizedPrefix,
      hostCount: hostCount,
      networkInt: networkInt,
      broadcastInt: broadcastInt,
    );
  }

  static List<int> maskFromPrefix(int prefix) {
    final int normalized = prefix.clamp(0, 32).toInt();
    final List<int> mask = List<int>.filled(4, 0);
    for (int i = 0; i < 4; i++) {
      final int bits = normalized - (i * 8);
      if (bits >= 8) {
        mask[i] = 255;
      } else if (bits <= 0) {
        mask[i] = 0;
      } else {
        mask[i] = (0xFF << (8 - bits)) & 0xFF;
      }
    }
    return mask;
  }

  static int hostCountForPrefix(int prefix) {
    final int normalized = prefix.clamp(1, 32).toInt();
    return 1 << (32 - normalized);
  }

  static String formatIp(List<int> parts) => parts.join('.');

  static String formatBits(List<int> parts) => parts.map((int p) => p.toRadixString(2).padLeft(8, '0')).join('.');

  static List<int> intToIp(int value) => _intToIp(value);

  static List<int> _sanitizeIp(String rawIp) {
    final List<String> segments = (rawIp.trim().isEmpty ? '' : rawIp.trim()).split('.');
    segments.addAll(List<String>.filled(4, '0'));
    final List<int> result = List<int>.filled(4, 0);
    for (int i = 0; i < 4; i++) {
      final String segment = i < segments.length ? segments[i] : '0';
      final String digitsOnly = segment.replaceAll(RegExp(r'[^0-9]'), '');
      final String trimmed = digitsOnly.length <= 3 ? digitsOnly : digitsOnly.substring(digitsOnly.length - 3);
      int value = int.tryParse(trimmed) ?? 0;
      if (value < 0) {
        value = 0;
      } else if (value > 255) {
        value = 255;
      }
      result[i] = value;
    }
    return result;
  }

  static int _ipToInt(List<int> parts) {
    return (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8) | parts[3];
  }

  static List<int> _intToIp(int value) {
    final int normalized = value & 0xFFFFFFFF;
    return <int>[
      (normalized >> 24) & 0xFF,
      (normalized >> 16) & 0xFF,
      (normalized >> 8) & 0xFF,
      normalized & 0xFF,
    ];
  }
}

lib/cidr_home.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:intl/intl.dart';
import 'package:shared_preferences/shared_preferences.dart';

import 'ad_banner_widget.dart';
import 'ad_manager.dart';
import 'cidr_calculator.dart';
import 'const_value.dart';
import 'l10n/app_localizations.dart';
import 'setting_page.dart';

class CidrHome extends StatefulWidget {
  const CidrHome({
    super.key,
    required this.themeNumber,
    required this.localeLanguage,
    required this.onUpdateApp,
    required this.prefs,
  });

  final int themeNumber; // 0 system, 1 light, 2 dark
  final String localeLanguage; // '' system, 'en', 'ja'
  final void Function({required int themeNumber, required String localeLanguage}) onUpdateApp;
  final SharedPreferences prefs;

  @override
  State<CidrHome> createState() => _CidrHomeState();
}

class _CidrHomeState extends State<CidrHome> {
  late final TextEditingController _ipController;
  late final AdManager _adManager;
  late int _selectedPrefix; // CIDR prefix length 1..32
  late CidrCalculationResult _result;
  late int _themeNumber;
  late String _localeLanguage;

  @override
  void initState() {
    super.initState();
    _ipController = TextEditingController();
    _ipController.addListener(_recalculate);
    _selectedPrefix = 32;
    _adManager = AdManager();
    _themeNumber = <int>{0, 1, 2}.contains(widget.themeNumber) ? widget.themeNumber : 0;
    _localeLanguage = widget.localeLanguage;
    _result = CidrCalculator.calculate('', _selectedPrefix);
  }

  @override
  void didUpdateWidget(covariant CidrHome oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.themeNumber != widget.themeNumber) {
      _themeNumber = <int>{0, 1, 2}.contains(widget.themeNumber) ? widget.themeNumber : 0;
    }
    if (oldWidget.localeLanguage != widget.localeLanguage) {
      _localeLanguage = widget.localeLanguage;
    }
  }

  @override
  void dispose() {
    _ipController.removeListener(_recalculate);
    _ipController.dispose();
    _adManager.dispose();
    super.dispose();
  }

  void _recalculate() {
    if (!mounted) {
      return;
    }
    setState(() {
      _result = CidrCalculator.calculate(_ipController.text, _selectedPrefix);
    });
  }

  void _onPrefixChanged(int? prefix) {
    if (prefix == null || prefix == _selectedPrefix) {
      return;
    }
    setState(() {
      _selectedPrefix = prefix;
      _result = CidrCalculator.calculate(_ipController.text, _selectedPrefix);
    });
  }

  Future<void> _openSettings() async {
    final Map<String, dynamic>? result = await Navigator.of(context).push<Map<String, dynamic>>(
      MaterialPageRoute<Map<String, dynamic>>(
        builder: (BuildContext context) => SettingPage(
          themeNumber: _themeNumber,
          localeLanguage: _localeLanguage,
        ),
      ),
    );
    if (result == null) {
      return;
    }
    final int newThemeNumberRaw = (result[ConstValue.themeNumber] as int?) ?? _themeNumber;
    final int newThemeNumber = <int>{0, 1, 2}.contains(newThemeNumberRaw) ? newThemeNumberRaw : 0;
    final String newLocaleLanguage = (result[ConstValue.localeLanguage] as String?) ?? _localeLanguage;
    if (newThemeNumber == _themeNumber && newLocaleLanguage == _localeLanguage) {
      return;
    }
    await widget.prefs.setInt(ConstValue.themeNumber, newThemeNumber);
    await widget.prefs.setString(ConstValue.localeLanguage, newLocaleLanguage);
    setState(() {
      _themeNumber = newThemeNumber;
      _localeLanguage = newLocaleLanguage;
    });
    widget.onUpdateApp(themeNumber: newThemeNumber, localeLanguage: newLocaleLanguage);
  }

  @override
  Widget build(BuildContext context) {
    final AppLocalizations l = AppLocalizations.of(context);
    final Locale locale = Localizations.localeOf(context);
    final TextTheme textTheme = Theme.of(context).textTheme;
    final ColorScheme colors = Theme.of(context).colorScheme;

    final String ipDisplay = _result.sanitizedIp;
    final String networkDisplay = CidrCalculator.formatIp(_result.networkParts);
    final String broadcastDisplay = CidrCalculator.formatIp(_result.broadcastParts);
    final String maskDisplay = CidrCalculator.formatIp(_result.maskParts);
    final String cidrDisplay = '$networkDisplay/${_result.prefix}';
    final String rangeDisplay = '$networkDisplay - $broadcastDisplay';
    final String hostRangeDisplay = _formatHostRange(l, _result);
    final String ipBitsDisplay = CidrCalculator.formatBits(_result.ipParts);
    final String maskBitsDisplay = CidrCalculator.formatBits(_result.maskParts);

    return Scaffold(
      backgroundColor: colors.brightness == Brightness.light ? ConstValue.bgColors.back1.light : ConstValue.bgColors.back1.dark,
      body: GestureDetector(
        onTap: () => FocusScope.of(context).unfocus(),
        child: SafeArea(
          child: Column(
            children: <Widget>[
              Expanded(
                child: SingleChildScrollView(
                  padding: const EdgeInsets.symmetric(horizontal: 0, vertical: 24),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: <Widget>[
                      _buildHeader(l, textTheme, colors),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back2.light : ConstValue.bgColors.back2.dark,
                        child: _buildInputIp(l, locale, textTheme),
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back3.light : ConstValue.bgColors.back3.dark,
                        child: _buildInputMask(l, locale, textTheme)
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back4.light : ConstValue.bgColors.back4.dark,
                        child: _buildResult(l.labelIp, ipDisplay, textTheme, colors),
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back5.light : ConstValue.bgColors.back5.dark,
                        child: _buildResult(l.labelRange, rangeDisplay, textTheme, colors),
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back6.light : ConstValue.bgColors.back6.dark,
                        child: _buildResult(l.labelNetwork, networkDisplay, textTheme, colors),
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back7.light : ConstValue.bgColors.back7.dark,
                        child: _buildResult(l.labelHostRange, hostRangeDisplay, textTheme, colors),
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back8.light : ConstValue.bgColors.back8.dark,
                        child: _buildResult(l.labelBroadcast, broadcastDisplay, textTheme, colors),
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back9.light : ConstValue.bgColors.back9.dark,
                        child: _buildResult(l.labelCidr, cidrDisplay, textTheme, colors),
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back10.light : ConstValue.bgColors.back10.dark,
                        child: _buildResult(l.labelMask, maskDisplay, textTheme, colors),
                      ),
                      Container(
                        color: colors.brightness == Brightness.light ? ConstValue.bgColors.back11.light : ConstValue.bgColors.back11.dark,
                        child: _buildBits(l.labelBits, ipBitsDisplay, maskBitsDisplay, textTheme, colors),
                      ),
                    ],
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
      bottomNavigationBar: AdBannerWidget(adManager: _adManager),
    );
  }

  Widget _buildHeader(AppLocalizations l, TextTheme textTheme, ColorScheme colors) {
    return Row(children: [
      Padding(
        padding: const EdgeInsets.only(left: 10),
        child: Text(l.appTitle,style: textTheme.titleMedium?.copyWith(fontWeight: FontWeight.bold, color: Colors.white54))
      ),
      const Spacer(),
      Padding(
        padding: const EdgeInsets.only(right: 8),
        child: IconButton(
          onPressed: _openSettings,
          tooltip: l.setting,
          icon: Icon(Icons.settings, color: Colors.white54),
        ),
      ),
    ]);
  }

  Widget _buildInputIp(AppLocalizations l, Locale locale, TextTheme textTheme) {
    final ColorScheme colors = Theme.of(context).colorScheme;
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          Column(crossAxisAlignment: CrossAxisAlignment.start,children: [
            Row(
              children: [
                Text(l.inputIp,style: textTheme.bodySmall),
                const SizedBox(width: 12),
                Expanded(
                  child: TextField(
                    controller: _ipController,
                    keyboardType: const TextInputType.numberWithOptions(decimal: true),
                    style: textTheme.bodyMedium?.copyWith(fontFamily: 'monospace',fontWeight: FontWeight.w600),
                    inputFormatters: <TextInputFormatter>[
                      FilteringTextInputFormatter.allow(RegExp(r'[0-9.]')),
                    ],
                    decoration: InputDecoration(
                      hintText: '0.0.0.0',
                      filled: true,
                      fillColor: Colors.transparent,
                    ),
                  ),
                ),
              ],
            ),
          ]),
        ],
      )
    );
  }

  Widget _buildInputMask(AppLocalizations l, Locale locale, TextTheme textTheme) {
    final ColorScheme colors = Theme.of(context).colorScheme;
    final NumberFormat numberFormat = NumberFormat.decimalPattern(locale.languageCode);
    final List<DropdownMenuItem<int>> items = List<DropdownMenuItem<int>>.generate(32, (int index) {
      final int prefix = 32 - index;
      final String optionLabel = _formatSubnetOption(prefix, numberFormat);
      return DropdownMenuItem<int>(
        value: prefix,
        child: Text(optionLabel, style: textTheme.bodyMedium),
      );
    });
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          Column(crossAxisAlignment: CrossAxisAlignment.start,children: [
            Text(l.inputSubnet, style: textTheme.bodySmall),
            InputDecorator(
              decoration: InputDecoration(
                filled: true,
                fillColor: Colors.transparent,
                contentPadding: const EdgeInsets.symmetric(horizontal: 12, vertical: 2),
              ),
              child: DropdownButtonHideUnderline(
                child: DropdownButton<int>(
                  value: _selectedPrefix,
                  isExpanded: true,
                  items: items,
                  onChanged: _onPrefixChanged,
                  style: textTheme.bodyMedium?.copyWith(fontFamily: 'monospace',fontWeight: FontWeight.w600),
                ),
              ),
            ),
          ])
        ],
      )
    );
  }

  Widget _buildResult(String label, String value, TextTheme textTheme, ColorScheme colors) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 12),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          Expanded(
            flex: 4,
            child: Text(label,style: textTheme.bodySmall),
          ),
          Expanded(
            flex: 7,
            child: Text(value,style: textTheme.bodyMedium?.copyWith(fontFamily: 'monospace',fontWeight: FontWeight.w600)),
          ),
        ],
      ),
    );
  }

  Widget _buildBits(String label, String ipBits, String maskBits, TextTheme textTheme, ColorScheme colors) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 12),
      child: SizedBox(
        width: double.infinity, // 横幅100%
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text(
              label,
              style: textTheme.bodySmall,
            ),
            const SizedBox(height: 2),
            Text(
              ipBits,
              style: textTheme.bodyMedium?.copyWith(fontFamily: 'monospace',fontWeight: FontWeight.w600),
            ),
            Text(
              maskBits,
              style: textTheme.bodyMedium?.copyWith(fontFamily: 'monospace',fontWeight: FontWeight.w600),
            ),
          ],
        ),
      ),
    );
  }

  String _formatSubnetOption(int prefix, NumberFormat numberFormat) {
    final List<int> maskParts = CidrCalculator.maskFromPrefix(prefix);
    final String mask = CidrCalculator.formatIp(maskParts);
    final int hostCount = CidrCalculator.hostCountForPrefix(prefix);
    final String hostCountString = numberFormat.format(hostCount);
    return '$mask (/$prefix) [$hostCountString]';
  }

  String _formatHostRange(AppLocalizations l, CidrCalculationResult result) {
    final String network = CidrCalculator.formatIp(result.networkParts);
    final String broadcast = CidrCalculator.formatIp(result.broadcastParts);
    if (result.hostCount <= 1) {
      return '$network ${l.hostSingleSuffix}';
    }
    if (result.hostCount == 2) {
      return '$network - $broadcast ${l.hostTwoSuffix}';
    }
    final List<int> firstHost = CidrCalculator.intToIp(result.networkInt + 1);
    final List<int> lastHost = CidrCalculator.intToIp(result.broadcastInt - 1);
    return '${CidrCalculator.formatIp(firstHost)} - ${CidrCalculator.formatIp(lastHost)}';
  }
}

lib/const_value.dart

import 'package:flutter/material.dart';

class ConstValue {
  static const String settings = 'settings';
  static const String localeLanguage = 'localeLanguage';
  static const String themeNumber = 'themeNumber'; // 0 system, 1 light, 2 dark
  static const BgColors bgColors = BgColors();
}

class BgColors {
  const BgColors();
  final BackColor back1 = const BackColor(
    light: Color(0xFFc19fd8),
    dark: Color(0xFF5d3e73),
  );
  final BackColor back2 = const BackColor(
    light: Color(0xFFaa9fd8),
    dark: Color(0xFF483d73),
  );
  final BackColor back3 = const BackColor(
    light: Color(0xFFa0abd8),
    dark: Color(0xFF3e4873),
  );
  final BackColor back4 = const BackColor(
    light: Color(0xFF9fbcd9),
    dark: Color(0xFF3d5873),
  );
  final BackColor back5 = const BackColor(
    light: Color(0xFF9ecfdb),
    dark: Color(0xFF3d6a75),
  );
  final BackColor back6 = const BackColor(
    light: Color(0xFF9edcce),
    dark: Color(0xFF3c7669),
  );
  final BackColor back7 = const BackColor(
    light: Color(0xFF9edcad),
    dark: Color(0xFF3c764b),
  );
  final BackColor back8 = const BackColor(
    light: Color(0xFFb5dca4),
    dark: Color(0xFF527642),
  );
  final BackColor back9 = const BackColor(
    light: Color(0xFFd8dca4),
    dark: Color(0xFF727643),
  );
  final BackColor back10 = const BackColor(
    light: Color(0xFFdbc3a4),
    dark: Color(0xFF765e42),
  );
  final BackColor back11 = const BackColor(
    light: Color(0xFFdbafa2),
    dark: Color(0xFF764b40),
  );
  final BackColor back12 = const BackColor(
    light: Color(0xFFdba0b0),
    dark: Color(0xFF763e4d),
  );
  final BackColor back13 = const BackColor(
    light: Color(0xFFdba0cc),
    dark: Color(0xFF763e68),
  );
}

class BackColor {
  final Color light;
  final Color dark;
  const BackColor({required this.light, required this.dark});
}

lib/main.dart

import 'package:flutter/material.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';
import 'package:shared_preferences/shared_preferences.dart';

import 'cidr_home.dart';
import 'const_value.dart';
import 'l10n/app_localizations.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await MobileAds.instance.initialize();
  final SharedPreferences prefs = await SharedPreferences.getInstance();
  final int initialThemeNumber = prefs.getInt(ConstValue.themeNumber) ?? 0;
  final String initialLocaleLanguage = prefs.getString(ConstValue.localeLanguage) ?? '';
  runApp(CidrApp(
    prefs: prefs,
    initialThemeNumber: initialThemeNumber,
    initialLocaleLanguage: initialLocaleLanguage,
  ));
}

class CidrApp extends StatefulWidget {
  const CidrApp({
    super.key,
    required this.prefs,
    required this.initialThemeNumber,
    required this.initialLocaleLanguage,
  });

  final SharedPreferences prefs;
  final int initialThemeNumber;
  final String initialLocaleLanguage;

  @override
  State<CidrApp> createState() => _CidrAppState();
}

class _CidrAppState extends State<CidrApp> {
  late int _themeNumber; // 0 system, 1 light, 2 dark
  late String _localeLanguage; // '' system default, otherwise language code

  @override
  void initState() {
    super.initState();
    _themeNumber = _normalizeThemeNumber(widget.initialThemeNumber);
    _localeLanguage = widget.initialLocaleLanguage;
  }

  void _updateThemeAndLocale({required int themeNumber, required String localeLanguage}) {
    setState(() {
      _themeNumber = _normalizeThemeNumber(themeNumber);
      _localeLanguage = localeLanguage;
    });
  }

  int _normalizeThemeNumber(int value) {
    if (value < 0 || value > 2) {
      return 0;
    }
    return value;
  }

  ThemeMode get _themeMode {
    switch (_themeNumber) {
      case 2:
        return ThemeMode.dark;
      case 1:
        return ThemeMode.light;
      default:
        return ThemeMode.system;
    }
  }

  Locale? get _locale => _localeLanguage.isEmpty ? null : Locale(_localeLanguage);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'CIDR',
      themeMode: _themeMode,
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.blueGrey),
        useMaterial3: true,
      ),
      darkTheme: ThemeData.dark(useMaterial3: true),
      locale: _locale,
      localizationsDelegates: AppLocalizations.localizationsDelegates,
      supportedLocales: AppLocalizations.supportedLocales,
      home: CidrHome(
        themeNumber: _themeNumber,
        localeLanguage: _localeLanguage,
        onUpdateApp: _updateThemeAndLocale,
        prefs: widget.prefs,
      ),
    );
  }
}

lib/setting_page.dart

import 'package:flutter/material.dart';

import 'ad_banner_widget.dart';
import 'ad_manager.dart';
import 'const_value.dart';
import 'l10n/app_localizations.dart';

class SettingPage extends StatefulWidget {
  const SettingPage({super.key, required this.themeNumber, required this.localeLanguage});

  final int themeNumber; // 0 system, 1 light, 2 dark
  final String localeLanguage; // '' system default, otherwise language code

  @override
  State<SettingPage> createState() => _SettingPageState();
}

class _SettingPageState extends State<SettingPage> {
  static const Map<String, String> _languageOptions = <String, String>{
    'en': 'English',
    'ja': '日本語',
  };

  late int _themeNumber; // 0 system, 1 light, 2 dark
  late String _languageCode;
  late AdManager _adManager;

  @override
  void initState() {
    super.initState();
    _themeNumber = <int>{0, 1, 2}.contains(widget.themeNumber) ? widget.themeNumber : 0;
    _languageCode = widget.localeLanguage;
    if (_languageCode.isNotEmpty && !_languageOptions.containsKey(_languageCode)) {
      _languageCode = '';
    }
    _adManager = AdManager();
  }

  @override
  void dispose() {
    _adManager.dispose();
    super.dispose();
  }

  void _onApply() {
    Navigator.of(context).pop(<String, Object?>{
      ConstValue.themeNumber: _themeNumber,
      ConstValue.localeLanguage: _languageCode,
    });
  }

  @override
  Widget build(BuildContext context) {
    final AppLocalizations l = AppLocalizations.of(context);
    return Scaffold(
      appBar: AppBar(
        automaticallyImplyLeading: false,
        leading: IconButton(
          icon: const Icon(Icons.close),
          tooltip: l.cancel,
          onPressed: () => Navigator.of(context).pop(),
        ),
        actions: <Widget>[
          Padding(
          padding: const EdgeInsets.only(right: 10),
            child: IconButton(
              icon: const Icon(Icons.check),
              tooltip: l.apply,
              onPressed: _onApply,
            ),
          ),
        ],
      ),
      body: SafeArea(
        child: ListView(
          padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 24),
          children: <Widget>[
            _buildThemeTile(l),
            const Divider(),
            _buildLanguageTile(l),
            const SizedBox(height: 120),
          ],
        ),
      ),
      bottomNavigationBar: AdBannerWidget(adManager: _adManager),
    );
  }

  Widget _buildThemeTile(AppLocalizations l) {
    return ListTile(
      contentPadding: const EdgeInsets.only(left: 16, right: 10),
      title: Text(l.theme),
      trailing: DropdownButton<int>(
        value: _themeNumber,
        items: <DropdownMenuItem<int>>[
          DropdownMenuItem<int>(value: 0, child: Text(l.systemDefault)),
          DropdownMenuItem<int>(value: 1, child: Text(l.lightTheme)),
          DropdownMenuItem<int>(value: 2, child: Text(l.darkTheme)),
        ],
        onChanged: (int? value) {
          if (value == null) {
            return;
          }
          setState(() => _themeNumber = value);
        },
      ),
    );
  }

  Widget _buildLanguageTile(AppLocalizations l) {
    final String? dropdownValue = _languageCode.isEmpty ? null : _languageCode;
    return ListTile(
      contentPadding: const EdgeInsets.only(left: 16, right: 10),
      title: Text(l.language),
      trailing: DropdownButton<String?>(
        value: dropdownValue,
        hint: Text(l.systemDefault),
        items: <DropdownMenuItem<String?>>[
          DropdownMenuItem<String?>(value: null, child: Text(l.systemDefault))
        ]
            .followedBy(
              _languageOptions.entries.map(
                (MapEntry<String, String> entry) => DropdownMenuItem<String?>(
                  value: entry.key,
                  child: Text(entry.value),
                ),
              ),
            )
            .toList(),
        onChanged: (String? value) {
          setState(() => _languageCode = value ?? '');
        },
      ),
    );
  }
}