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

import '../app/locale_controller.dart';
import '../core/api_client.dart';
import '../features/uploads/engine_scope.dart';
import '../features/uploads/queue_controller.dart';
import '../l10n/app_localizations.dart';
import 'albums_tab.dart';
import 'queue_tab.dart';

/// 主壳：底部导航「相册 / 上传 / 设置」（UI-01 §4.1）。
///
/// IndexedStack 保持三页签状态；「上传」页签角标 = 当前账号未结束任务数
/// （[unfinishedCountOf]，TaskStore 账号硬隔离，不跨账号），为 0 时隐藏。
class HomePage extends ConsumerStatefulWidget {
  const HomePage({super.key});

  @override
  ConsumerState<HomePage> createState() => _HomePageState();
}

class _HomePageState extends ConsumerState<HomePage> {
  int _selectedIndex = 0;

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final badgeCount = ref.watch(uploadBadgeCountProvider);
    return Scaffold(
      body: IndexedStack(
        index: _selectedIndex,
        children: const [AlbumsTab(), QueueTab(), SettingsTab()],
      ),
      bottomNavigationBar: NavigationBar(
        selectedIndex: _selectedIndex,
        onDestinationSelected: (index) =>
            setState(() => _selectedIndex = index),
        destinations: [
          NavigationDestination(
            icon: const Icon(Icons.photo_library_outlined),
            selectedIcon: const Icon(Icons.photo_library),
            label: l10n.navAlbums,
          ),
          NavigationDestination(
            icon: _UploadTabIcon(
              count: badgeCount,
              icon: Icons.cloud_upload_outlined,
            ),
            selectedIcon: _UploadTabIcon(
              count: badgeCount,
              icon: Icons.cloud_upload,
            ),
            label: l10n.navUploads,
          ),
          NavigationDestination(
            icon: const Icon(Icons.settings_outlined),
            selectedIcon: const Icon(Icons.settings),
            label: l10n.navSettings,
          ),
        ],
      ),
    );
  }
}

/// 上传页签图标 + 未完成任务角标（≤0 时隐藏 Badge，仅图标）。
///
/// Semantics 携带本地化计数文案（读屏不依赖角标视觉）。
class _UploadTabIcon extends StatelessWidget {
  const _UploadTabIcon({required this.count, required this.icon});

  final int count;
  final IconData icon;

  @override
  Widget build(BuildContext context) {
    if (count <= 0) return Icon(icon);
    return Semantics(
      label: AppLocalizations.of(context).badgeUploading(count),
      child: Badge.count(count: count, child: Icon(icon)),
    );
  }
}

/// 设置页（P3 Task 3：修改密码入口 + 退出登录；Task 10：语言切换）。
class SettingsTab extends ConsumerWidget {
  const SettingsTab({super.key});

  /// 档位 → 展示名（语言名固定以自身语言书写，不随当前界面语言变化）。
  static String _choiceLabel(AppLocalizations l10n, AppLocaleChoice choice) =>
      switch (choice) {
        AppLocaleChoice.system => l10n.localeFollowSystem,
        AppLocaleChoice.zh => l10n.localeChinese,
        AppLocaleChoice.en => l10n.localeEnglish,
      };

  Future<void> _pickLocale(
    BuildContext context,
    WidgetRef ref,
    AppLocaleChoice current,
  ) {
    return showModalBottomSheet<void>(
      context: context,
      showDragHandle: true,
      builder: (sheetContext) {
        final l10n = AppLocalizations.of(sheetContext);
        // 打开时刻的快照即可：选中即 pop，无滞留期间的陈旧选中态。
        return SafeArea(
          child: RadioGroup<AppLocaleChoice>(
            groupValue: current,
            onChanged: (choice) {
              if (choice == null) return;
              ref.read(localeSettingsProvider.notifier).setChoice(choice);
              Navigator.of(sheetContext).pop();
            },
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                for (final choice in AppLocaleChoice.values)
                  RadioListTile<AppLocaleChoice>(
                    value: choice,
                    title: Text(_choiceLabel(l10n, choice)),
                  ),
              ],
            ),
          ),
        );
      },
    );
  }

  Future<void> _logout(BuildContext context, WidgetRef ref) async {
    // api.logout 尽力而为（服务端撤销失败也照常本地清会话——客户端内已处理）。
    await ref.read(apiClientProvider).logout();
    // 会话账号失效 → 引擎 stop（任务保留库内，见 engine_scope.dart）。
    await ref.read(sessionAccountProvider.notifier).refresh();
    if (!context.mounted) return;
    Navigator.of(context).pushNamedAndRemoveUntil('/login', (route) => false);
  }

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final choice = ref.watch(localeSettingsProvider);
    return Scaffold(
      appBar: AppBar(title: Text(l10n.settings)),
      body: ListView(
        children: [
          ListTile(
            leading: const Icon(Icons.language),
            title: Text(l10n.language),
            subtitle: Text(_choiceLabel(l10n, choice)),
            onTap: () => _pickLocale(context, ref, choice),
          ),
          ListTile(
            leading: const Icon(Icons.password_outlined),
            title: Text(l10n.passwordChangeTitle),
            onTap: () => Navigator.of(context).pushNamed('/password-change'),
          ),
          ListTile(
            leading: const Icon(Icons.logout),
            title: Text(l10n.logout),
            onTap: () => _logout(context, ref),
          ),
        ],
      ),
    );
  }
}