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

import '../app/locale_controller.dart';
import '../core/api_client.dart';
import '../features/albums/providers.dart';
import '../features/uploads/engine_scope.dart';
import '../features/uploads/queue_controller.dart';
import '../l10n/app_localizations.dart';
import '../ui/components/language_sheet.dart';
import '../ui/components/section_header.dart';
import '../ui/tokens.dart';
import 'albums_tab.dart';
import 'queue_tab.dart';

/// 应用展示版本（About 分组）：与 pubspec version 对齐的缺省值，
/// `--dart-define=APP_VERSION=...` 覆盖（未引入 package_info，零新依赖）。
const String kAppVersion = String.fromEnvironment(
  'APP_VERSION',
  defaultValue: '1.0.0',
);

/// 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),
      // UI06：app-preview .badge——红底 #F15B64 白字 + 白边（与导航白底分隔）。
      child: Badge.count(
        count: count,
        backgroundColor: const Color(0xFFF15B64),
        textStyle: const TextStyle(
          fontSize: 10,
          color: Colors.white,
          fontWeight: FontWeight.w600,
        ),
        smallSize: 16,
        child: Icon(icon),
      ),
    );
  }
}

/// 设置页（UI-03 页面 02 重设计，图01）：账号摘要卡（首字母头像 + 账号）
/// → 通用分组（Language / Change password / Upload help / App version）
/// → 退出登录（低强调红色，单独分离）。
///
/// 账号卡不是「编辑资料」入口（无编辑功能，无导航箭头）；会话契约无
/// 自身显示名/角色字段，卡片只展示真实可得的账号。语言行显示档位
/// 自身名称；版本取 [kAppVersion]。上传帮助为本地说明面板（不承诺
/// 后台百分百持续）。退出若存在进行中任务，确认弹窗明确任务保留、
/// 重新登录后继续——不承诺退出后后台继续上传。
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,
      };

  /// 上传帮助面板（本地说明：网络等待/系统后台限制/强退恢复）。
  Future<void> _showUploadHelp(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    return showModalBottomSheet<void>(
      context: context,
      showDragHandle: true,
      builder: (sheetContext) => SafeArea(
        top: false,
        child: SingleChildScrollView(
          // 长文案/大字体下允许滚动，面板不做固定高度。
          child: Padding(
            padding: const EdgeInsets.fromLTRB(kSpace24, 0, kSpace24, kSpace24),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                Text(
                  l10n.settingsUploadHelpTitle,
                  style: theme.textTheme.titleMedium,
                ),
                const SizedBox(height: kSpace12),
                Text(
                  l10n.settingsUploadHelpBody,
                  style: theme.textTheme.bodyMedium?.copyWith(
                    color: theme.colorScheme.onSurfaceVariant,
                    height: 1.5,
                  ),
                ),
                const SizedBox(height: kSpace16),
                FilledButton(
                  onPressed: () => Navigator.of(sheetContext).pop(),
                  child: Text(l10n.ok),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }

  /// 退出确认：有进行中任务时明确本地任务保留、重新登录后继续
  /// （不承诺后台继续上传）；无任务时为常规确认。
  Future<void> _confirmLogout(
    BuildContext context,
    WidgetRef ref,
    int unfinishedTasks,
  ) async {
    final l10n = AppLocalizations.of(context);
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (dialogContext) => AlertDialog(
        title: Text(l10n.logoutConfirmTitle),
        content: Text(
          unfinishedTasks > 0
              ? l10n.logoutConfirmBody
              : l10n.logoutConfirmBodyIdle,
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(dialogContext).pop(false),
            child: Text(l10n.cancel),
          ),
          FilledButton(
            onPressed: () => Navigator.of(dialogContext).pop(true),
            child: Text(l10n.logout),
          ),
        ],
      ),
    );
    if (confirmed != true || !context.mounted) return;
    await _logout(context, ref);
  }

  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();
    // 账号级缓存失效（2026-09-23 用户报告：换账号后相册列表仍是上一账号数据
    // ——首页 IndexedStack 三 tab 常驻不销毁，非 autoDispose 的列表 Provider
    // 必须显式失效；任务库已按账号隔离键隔离，无需清）。
    ref.invalidate(albumListProvider);
    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);
    final account = ref.watch(sessionAccountProvider).value;
    // 进行中任务数（底部导航角标同口径）：退出确认文案分流。
    final unfinishedTasks = ref.watch(uploadBadgeCountProvider);
    final theme = Theme.of(context);
    return Scaffold(
      appBar: AppBar(title: Text(l10n.settings)),
      body: ListView(
        padding: const EdgeInsets.fromLTRB(0, kSpace8, 0, kSpace24),
        children: [
          // ── 账号摘要卡（只读展示，非编辑入口） ─────────────────
          Padding(
            padding: const EdgeInsets.fromLTRB(
              kSpace16,
              kSpace8,
              kSpace16,
              kSpace8,
            ),
            child: SectionHeader(title: l10n.settingsSectionAccount),
          ),
          Card(
            margin: const EdgeInsets.symmetric(horizontal: kSpace16),
            child: Padding(
              padding: const EdgeInsets.all(kSpace16),
              child: Row(
                children: [
                  _AccountAvatar(account: account),
                  const SizedBox(width: kSpace16),
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Text(
                          account ?? l10n.notSet,
                          maxLines: 1,
                          overflow: TextOverflow.ellipsis,
                          style: theme.textTheme.titleSmall,
                        ),
                        const SizedBox(height: kSpace4),
                        Text(
                          l10n.settingsSignedInAccount,
                          style: theme.textTheme.bodySmall,
                        ),
                      ],
                    ),
                  ),
                ],
              ),
            ),
          ),
          // ── 通用：语言 / 改密 / 上传帮助 / 版本 ──────────────────
          Padding(
            padding: const EdgeInsets.fromLTRB(
              kSpace16,
              kSpace24,
              kSpace16,
              kSpace8,
            ),
            child: SectionHeader(title: l10n.settingsSectionGeneral),
          ),
          Card(
            margin: const EdgeInsets.symmetric(horizontal: kSpace16),
            clipBehavior: Clip.antiAlias,
            child: Column(
              children: [
                _SettingsRow(
                  icon: Icons.language,
                  label: l10n.language,
                  trailing: Text(
                    _choiceLabel(l10n, choice),
                    style: theme.textTheme.bodyMedium?.copyWith(
                      color: theme.colorScheme.onSurfaceVariant,
                    ),
                  ),
                  chevron: true,
                  onTap: () => showLanguageSheet(context),
                ),
                const Divider(indent: kSpace16, endIndent: kSpace16),
                _SettingsRow(
                  icon: Icons.password_outlined,
                  label: l10n.passwordChangeTitle,
                  chevron: true,
                  onTap: () =>
                      Navigator.of(context).pushNamed('/password-change'),
                ),
                const Divider(indent: kSpace16, endIndent: kSpace16),
                _SettingsRow(
                  icon: Icons.help_outline,
                  label: l10n.settingsSectionUploadHelp,
                  chevron: true,
                  onTap: () => _showUploadHelp(context),
                ),
                const Divider(indent: kSpace16, endIndent: kSpace16),
                _SettingsRow(
                  icon: Icons.info_outline,
                  label: l10n.settingsVersion,
                  trailing: Text(
                    kAppVersion,
                    style: theme.textTheme.bodyMedium?.copyWith(
                      color: theme.colorScheme.onSurfaceVariant,
                    ),
                  ),
                ),
              ],
            ),
          ),
          // ── 退出登录：低强调红色，与常规分组分离 ─────────────────
          Padding(
            padding: const EdgeInsets.only(top: kSpace24),
            child: Align(
              alignment: Alignment.center,
              child: TextButton(
                style: TextButton.styleFrom(
                  foregroundColor: theme.colorScheme.error,
                  minimumSize: const Size(48, 48),
                ),
                onPressed: () => _confirmLogout(context, ref, unfinishedTasks),
                child: Text(l10n.logout),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

/// 账号首字母头像占位（无真实头像数据；缺失回退「?」）。
class _AccountAvatar extends StatelessWidget {
  const _AccountAvatar({required this.account});

  final String? account;

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    final initial = (account == null || account!.isEmpty)
        ? '?'
        : account!.characters.first.toUpperCase();
    return CircleAvatar(
      radius: 24,
      backgroundColor: scheme.primary,
      foregroundColor: scheme.onPrimary,
      child: Text(initial, style: Theme.of(context).textTheme.titleMedium),
    );
  }
}

/// 设置行：图标 + 标题 + 可选尾值/箭头，触控高 ≥48。
class _SettingsRow extends StatelessWidget {
  const _SettingsRow({
    required this.icon,
    required this.label,
    this.trailing,
    this.chevron = false,
    this.onTap,
  });

  final IconData icon;
  final String label;
  final Widget? trailing;

  /// 是否显示导航箭头（仅可进入的行显示）。
  final bool chevron;
  final VoidCallback? onTap;

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    return InkWell(
      onTap: onTap,
      child: ConstrainedBox(
        constraints: const BoxConstraints(minHeight: 56),
        child: Padding(
          padding: const EdgeInsets.symmetric(
            horizontal: kSpace16,
            vertical: kSpace12,
          ),
          child: Row(
            children: [
              Icon(icon, size: 24, color: scheme.onSurfaceVariant),
              const SizedBox(width: kSpace16),
              Expanded(
                child: Text(
                  label,
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                  style: Theme.of(context).textTheme.bodyLarge,
                ),
              ),
              if (trailing != null) ...[
                const SizedBox(width: kSpace8),
                trailing!,
              ],
              if (chevron) ...[
                const SizedBox(width: kSpace4),
                Icon(
                  Icons.chevron_right,
                  size: 24,
                  color: scheme.onSurfaceVariant,
                ),
              ],
            ],
          ),
        ),
      ),
    );
  }
}