flutterApp/lib/components/language_selection_dialog.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

import 'package:maibu_satabot_v2/core/localization/app_localizations.dart';
import 'package:maibu_satabot_v2/core/localization/locale_cubit.dart';

/// 可选语言项：tag 对应 assets/languages/{tag}.json，nativeName 用该语言本地写法展示。
class LanguageItem {
  final Locale locale;
  final String nativeName;
  const LanguageItem(this.locale, this.nativeName);

  String get tag => locale.countryCode == null || locale.countryCode!.isEmpty
      ? locale.languageCode
      : '${locale.languageCode}-${locale.countryCode}';
}

/// 全局唯一的“可选语言列表”来源。
/// 后续接入“接口下载语言包”时，只需在这里扩展（例如把已下载的语言追加进来），
/// 登录强制弹窗与设置页入口都会自动同步，无需改多处。
class AppLanguages {
  AppLanguages._();
  static final AppLanguages instance = AppLanguages._();

  final List<LanguageItem> items = const [
    LanguageItem(AppLocalizations.chinese, '简体中文'),
    LanguageItem(AppLocalizations.english, 'English'),
  ];

  String nameOf(Locale locale) {
    final tag = locale.countryCode == null || locale.countryCode!.isEmpty
        ? locale.languageCode
        : '${locale.languageCode}-${locale.countryCode}';
    for (final item in items) {
      if (item.tag == tag) return item.nativeName;
    }
    return tag;
  }
}

/// 语言选择弹窗。
/// [mandatory] = true：登录时强制弹出，拦截系统返回键；可点某个语言即时切换，或点“继续”确认当前默认语言后关闭。
/// [mandatory] = false：设置页中普通选择，可取消。
class LanguageSelectionDialog extends StatelessWidget {
  final bool mandatory;
  const LanguageSelectionDialog({super.key, this.mandatory = true});

  void _onSelect(BuildContext context, Locale locale) {
    if (ModalRoute.of(context)?.isCurrent != true) return;
    unawaited(context.read<LocaleCubit>().setLocale(locale));
    Navigator.of(context).pop();
  }

  static const _navy = Color(0xFF1A2B4A);
  static const _blue = Color(0xFF1C96F6);
  static const _gray = Color(0xFF63758A);
  static const _border = Color(0xFFE5EDF7);
  static const _softBlue = Color(0xFFEAF3FE);

  @override
  Widget build(BuildContext context) {
    final current = context.select<LocaleCubit, Locale>((c) => c.state);
    final isChinese = current.languageCode == 'zh';
    final buttonShape = RoundedRectangleBorder(
      borderRadius: BorderRadius.circular(12),
    );

    return PopScope(
      canPop: !mandatory,
      child: Dialog(
        backgroundColor: Colors.white,
        surfaceTintColor: Colors.transparent,
        insetPadding: const EdgeInsets.symmetric(horizontal: 24, vertical: 20),
        constraints: const BoxConstraints(maxWidth: 360),
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(24)),
        child: SingleChildScrollView(
          padding: const EdgeInsets.all(20),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              Row(
                children: [
                  Container(
                    width: 44,
                    height: 44,
                    decoration: BoxDecoration(
                      color: _softBlue,
                      borderRadius: BorderRadius.circular(12),
                    ),
                    child: const Icon(Icons.language_rounded, color: _blue),
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Text(
                          isChinese ? '选择语言' : 'Select language',
                          style: const TextStyle(
                            color: _navy,
                            fontSize: 18,
                            fontWeight: FontWeight.w800,
                          ),
                        ),
                        const SizedBox(height: 2),
                        Text(
                          isChinese ? 'Select language' : '选择语言',
                          style: const TextStyle(color: _gray, fontSize: 12),
                        ),
                      ],
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 18),
              for (final item in AppLanguages.instance.items) ...[
                _languageOption(context, item, selected: item.locale == current),
                const SizedBox(height: 8),
              ],
              const SizedBox(height: 8),
              if (mandatory)
                FilledButton(
                  style: FilledButton.styleFrom(
                    backgroundColor: const Color(0xFF0B6DCC),
                    foregroundColor: Colors.white,
                    minimumSize: const Size.fromHeight(44),
                    shape: buttonShape,
                  ),
                  onPressed: () => _onSelect(context, current),
                  child: Text(isChinese ? '继续 / Continue' : 'Continue / 继续'),
                )
              else
                OutlinedButton(
                  style: OutlinedButton.styleFrom(
                    foregroundColor: _navy,
                    side: const BorderSide(color: _border),
                    minimumSize: const Size.fromHeight(44),
                    shape: buttonShape,
                  ),
                  onPressed: () => Navigator.of(context).pop(),
                  child: Text(
                    AppLocalizations.of(context).translate('common.cancel'),
                  ),
                ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _languageOption(
    BuildContext context,
    LanguageItem item, {
    required bool selected,
  }) {
    return Semantics(
      selected: selected,
      button: true,
      child: Material(
        color: selected ? _softBlue : const Color(0xFFF6FAFE),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(12),
          side: BorderSide(color: selected ? _blue : _border),
        ),
        clipBehavior: Clip.antiAlias,
        child: InkWell(
          onTap: () => _onSelect(context, item.locale),
          child: Padding(
            padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 14),
            child: Row(
              children: [
                Expanded(
                  child: Text(
                    item.nativeName,
                    style: const TextStyle(
                      color: _navy,
                      fontSize: 15,
                      fontWeight: FontWeight.w600,
                    ),
                  ),
                ),
                const SizedBox(width: 10),
                Icon(
                  selected
                      ? Icons.check_circle_rounded
                      : Icons.radio_button_unchecked_rounded,
                  size: 20,
                  color: selected ? _blue : const Color(0xFFABBBCD),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}