import 'package:flutter/material.dart';
import 'package:patbond_flutter/analytics/analytics_page_name.dart';
import 'package:patbond_flutter/core/navigation/fade_route.dart';
import 'package:patbond_flutter/core/network/api_exception.dart';
import 'package:patbond_flutter/core/theme/app_theme.dart';
import 'package:patbond_flutter/core/widgets/app_date_picker.dart';
import 'package:patbond_flutter/core/widgets/empty_state_illustration.dart';
import 'package:patbond_flutter/core/widgets/inline_error_banner.dart';
import 'package:patbond_flutter/core/widgets/record_type_dot.dart';
import 'package:patbond_flutter/features/pets/care_reminder_form_page.dart';
import 'package:patbond_flutter/features/pets/health_record_analytics.dart';
import 'package:patbond_flutter/features/pets/health_record_display.dart';
import 'package:patbond_flutter/features/pets/pet_display.dart';
import 'package:patbond_flutter/features/pets/pet_exceptions.dart';
import 'package:patbond_flutter/features/pets/pet_models.dart';
import 'package:patbond_flutter/features/pets/pets_repository.dart';
import 'package:patbond_flutter/widgets/common.dart';

enum _ListPhase { loading, ready, error }

/// 照护提醒页（T2-14）：契约不分页，`due_at ASC`（待办最先到期在前）；
/// `?status=` 过滤走服务端白名单视图；逾期待办有显性视觉标识。
///
/// - 完成 / 忽略：`PATCH /care-reminders/{id}` 状态流转
///   （pending→completed 必带 completedAt，pending→dismissed 禁带）；
///   42202 规则兜底、40902 并发流转抢先提示后重拉。
/// - 提醒完成/忽略**不埋事件**（06 §7 缺口 3 既定取舍：完成率从
///   care_reminders 事实表出数；M3+ 推送实验时再增补）。
/// - 曝光埋点：每次进入首个成功加载上报一次
///   `health_record_viewed(recordType=reminder, source=pet_detail)`。
class CareRemindersPage extends StatefulWidget {
  const CareRemindersPage({
    required this.repository,
    required this.petId,
    required this.canWrite,
    super.key,
    this.analytics,
  });

  final PetsRepository repository;
  final String petId;

  /// owner/caregiver 可写；viewer 隐藏创建与完成/忽略入口。
  final bool canWrite;

  final HealthRecordAnalytics? analytics;

  @override
  State<CareRemindersPage> createState() => _CareRemindersPageState();
}

class _CareRemindersPageState extends State<CareRemindersPage> {
  _ListPhase _phase = _ListPhase.loading;
  List<CareReminder> _reminders = const [];
  ApiException? _error;
  CareReminderStatus? _filter;
  bool _viewedFired = false;
  bool _mutating = false;

  @override
  void initState() {
    super.initState();
    _load();
  }

  Future<void> _load() async {
    setState(() {
      _phase = _ListPhase.loading;
      _error = null;
    });
    try {
      final reminders = await widget.repository.listCareReminders(
        widget.petId,
        status: _filter,
      );
      if (!mounted) return;
      setState(() {
        _reminders = reminders;
        _phase = _ListPhase.ready;
      });
      if (!_viewedFired) {
        _viewedFired = true;
        widget.analytics?.viewed(
          recordType: HealthRecordType.reminder,
          source: HealthRecordViewSource.petDetail,
        );
      }
    } on ApiException catch (error) {
      if (!mounted) return;
      setState(() {
        _error = error;
        _phase = _ListPhase.error;
      });
    }
  }

  Future<void> _openCreate() async {
    final created = await Navigator.of(context).push<CareReminder>(
      fadePageRoute(
        CareReminderFormPage(
          repository: widget.repository,
          petId: widget.petId,
          analytics: widget.analytics,
        ),
        settings: RouteSettings(name: AnalyticsPageName.recordForm.pageName),
      ),
    );
    if (created != null && mounted) {
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(const SnackBar(content: Text('已添加提醒')));
      // 排序键 due_at ASC 在服务端，重新拉取而非本地猜位置。
      await _load();
    }
  }

  /// 完成时刻：今日取此刻，补记历史日期取当日 12:00（本地），转 UTC。
  DateTime _completedAt(DateTime date) {
    final now = DateTime.now();
    final sameDay =
        date.year == now.year && date.month == now.month && date.day == now.day;
    final local = sameDay ? now : DateTime(date.year, date.month, date.day, 12);
    return local.toUtc();
  }

  Future<void> _complete(CareReminder reminder) async {
    final date = await showDialog<DateTime>(
      context: context,
      builder: (context) => _CompleteDialog(title: reminder.title),
    );
    if (date == null || !mounted) return;
    await _mutate(
      reminder,
      UpdateCareReminderRequest(
        status: CareReminderStatus.completed,
        // 契约：pending→completed 必带 completedAt（客户端提交，允许补记）。
        completedAt: _completedAt(date),
      ),
      successText: '已标记完成',
    );
  }

  Future<void> _dismiss(CareReminder reminder) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('忽略这条提醒？'),
        content: Text('「${reminder.title}」将不再出现在待办中，且不可恢复为待办。'),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(context).pop(false),
            child: const Text('取消'),
          ),
          FilledButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: const Text('忽略'),
          ),
        ],
      ),
    );
    if (confirmed != true || !mounted) return;
    await _mutate(
      reminder,
      // 契约：pending→dismissed 禁带 completedAt。
      const UpdateCareReminderRequest(status: CareReminderStatus.dismissed),
      successText: '已忽略提醒',
    );
  }

  Future<void> _mutate(
    CareReminder reminder,
    UpdateCareReminderRequest request, {
    required String successText,
  }) async {
    if (_mutating) return;
    setState(() => _mutating = true);
    final messenger = ScaffoldMessenger.of(context);
    try {
      await widget.repository.updateCareReminder(reminder.id, request);
      if (!mounted) return;
      messenger.showSnackBar(SnackBar(content: Text(successText)));
      await _load();
    } on CareReminderRuleException {
      if (!mounted) return;
      // 42202：状态机/completedAt 一致性兜底（前端结构上已按状态发字段）。
      messenger.showSnackBar(
        const SnackBar(content: Text('提醒状态不满足流转规则，已刷新，请重试')),
      );
      await _load();
    } on PetVersionConflictException {
      if (!mounted) return;
      // 40902：并发流转抢先（条件更新守卫落空），处理方式与乐观锁一致。
      messenger.showSnackBar(const SnackBar(content: Text('提醒已在其他设备被处理，已刷新')));
      await _load();
    } on PetRecordNotFoundException {
      if (!mounted) return;
      messenger.showSnackBar(const SnackBar(content: Text('提醒不存在或已被删除，已刷新')));
      await _load();
    } on PetAccessDeniedException {
      if (!mounted) return;
      messenger.showSnackBar(const SnackBar(content: Text('你没有权限操作该提醒')));
    } on ApiBusinessException {
      if (!mounted) return;
      messenger.showSnackBar(const SnackBar(content: Text('操作失败，请稍后重试')));
    } on ApiNetworkException {
      if (!mounted) return;
      messenger.showSnackBar(const SnackBar(content: Text('网络异常，请检查网络后重试')));
    } on SessionExpiredException {
      // 会话失效：认证状态机自动回登录页。
    } finally {
      if (mounted) setState(() => _mutating = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.transparent,
        elevation: 0,
        foregroundColor: AppColors.ink,
        title: const Text('照护提醒'),
        centerTitle: true,
        titleTextStyle: const TextStyle(
          color: AppColors.ink,
          fontSize: 16,
          fontWeight: FontWeight.w800,
        ),
        actions: [
          if (widget.canWrite && _phase == _ListPhase.ready)
            IconButton(
              tooltip: '添加提醒',
              onPressed: _openCreate,
              icon: const Icon(Icons.add),
            ),
        ],
      ),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.fromLTRB(16, 4, 16, 0),
            child: _filterChips(),
          ),
          Expanded(
            child: switch (_phase) {
              _ListPhase.loading => const Center(
                child: CircularProgressIndicator(),
              ),
              _ListPhase.error => Center(
                child: Padding(
                  padding: const EdgeInsets.all(24),
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      InlineErrorBanner(message: petLoadErrorMessage(_error)),
                      const SizedBox(height: 16),
                      FilledButton(onPressed: _load, child: const Text('重试')),
                    ],
                  ),
                ),
              ),
              _ListPhase.ready when _reminders.isEmpty => Center(
                child: SingleChildScrollView(child: _emptyState()),
              ),
              _ListPhase.ready => _list(),
            },
          ),
        ],
      ),
    );
  }

  /// 状态过滤（服务端白名单视图；「待办」即 ?status=pending 按 due_at 查询）。
  Widget _filterChips() {
    final options = <(String, CareReminderStatus?)>[
      ('全部', null),
      ('待办', CareReminderStatus.pending),
      ('已完成', CareReminderStatus.completed),
      ('已忽略', CareReminderStatus.dismissed),
    ];
    return SingleChildScrollView(
      scrollDirection: Axis.horizontal,
      child: Row(
        children: [
          for (final (label, status) in options)
            Padding(
              padding: const EdgeInsets.only(right: 8),
              child: ChoiceChip(
                label: Text(label),
                selected: _filter == status,
                onSelected: (_) {
                  if (_filter == status) return;
                  setState(() => _filter = status);
                  _load();
                },
              ),
            ),
        ],
      ),
    );
  }

  Widget _emptyState() {
    // 过滤视图下的空态不给 CTA（05 §4.2 筛选后空态惯例）。
    if (_filter != null) {
      return EmptyStateIllustration(
        icon: Icons.notifications_none_outlined,
        title: '暂无「${careReminderStatusLabel(_filter!)}」提醒',
      );
    }
    return EmptyStateIllustration(
      icon: Icons.notifications_none_outlined,
      title: '还没有照护提醒',
      description: '驱虫、体检、用药……到点不忘每一件照护小事',
      ctaLabel: widget.canWrite ? '添加第一条' : null,
      onCtaPressed: widget.canWrite ? _openCreate : null,
    );
  }

  Widget _list() {
    final now = DateTime.now();
    return RefreshIndicator(
      onRefresh: _load,
      child: ListView(
        padding: const EdgeInsets.fromLTRB(16, 8, 16, 30),
        children: [
          for (final reminder in _reminders) ...[
            _ReminderTile(
              reminder: reminder,
              now: now,
              // 完成/忽略仅对待办可用（终态不可迁；viewer 无写权限）。
              onComplete:
                  widget.canWrite &&
                      reminder.status == CareReminderStatus.pending &&
                      !_mutating
                  ? () => _complete(reminder)
                  : null,
              onDismiss:
                  widget.canWrite &&
                      reminder.status == CareReminderStatus.pending &&
                      !_mutating
                  ? () => _dismiss(reminder)
                  : null,
            ),
            const SizedBox(height: 10),
          ],
        ],
      ),
    );
  }
}

/// 提醒条目：RecordTypeDot + 标题 + 时间副行 + 状态 TagPill（逾期红标），
/// 待办行附「标记完成 / 忽略」动作（图标 + 文字双通道）。
class _ReminderTile extends StatelessWidget {
  const _ReminderTile({
    required this.reminder,
    required this.now,
    this.onComplete,
    this.onDismiss,
  });

  final CareReminder reminder;
  final DateTime now;
  final VoidCallback? onComplete;
  final VoidCallback? onDismiss;

  @override
  Widget build(BuildContext context) {
    final overdue = isReminderOverdue(reminder, now);
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(14),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                RecordTypeDot(
                  type: recordTypeForReminder(reminder.reminderType),
                  size: RecordTypeDotSize.md,
                ),
                const SizedBox(width: 12),
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        reminder.title,
                        maxLines: 1,
                        overflow: TextOverflow.ellipsis,
                        style: Theme.of(context).textTheme.titleMedium,
                      ),
                      const SizedBox(height: 4),
                      Text(
                        '${careReminderTypeLabel(reminder.reminderType)} · '
                        '${reminderDateLine(reminder)}',
                        maxLines: 1,
                        overflow: TextOverflow.ellipsis,
                        style: TextStyle(
                          // 逾期副行同步警示色（与标签双位标识）。
                          color: overdue
                              ? AppColors.errorDark
                              : AppColors.inkSoft,
                          fontSize: 12,
                          fontWeight: overdue
                              ? FontWeight.w700
                              : FontWeight.w400,
                        ),
                      ),
                    ],
                  ),
                ),
                const SizedBox(width: 8),
                TagPill(
                  reminderStatusTag(reminder, now),
                  color: reminderStatusColor(reminder, now),
                ),
              ],
            ),
            if (onComplete != null || onDismiss != null) ...[
              const SizedBox(height: 6),
              Row(
                mainAxisAlignment: MainAxisAlignment.end,
                children: [
                  TextButton.icon(
                    onPressed: onDismiss,
                    icon: const Icon(Icons.close, size: 16),
                    style: TextButton.styleFrom(
                      foregroundColor: AppColors.inkSoft,
                    ),
                    label: const Text('忽略'),
                  ),
                  const SizedBox(width: 4),
                  TextButton.icon(
                    onPressed: onComplete,
                    icon: const Icon(Icons.check_circle_outline, size: 16),
                    label: const Text('标记完成'),
                  ),
                ],
              ),
            ],
          ],
        ),
      ),
    );
  }
}

/// 标记完成对话框：完成日期默认今天，可补记历史时刻（契约 completedAt
/// 由客户端提交）。确认返回所选日期。
class _CompleteDialog extends StatefulWidget {
  const _CompleteDialog({required this.title});

  final String title;

  @override
  State<_CompleteDialog> createState() => _CompleteDialogState();
}

class _CompleteDialogState extends State<_CompleteDialog> {
  DateTime _date = DateTime.now();

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: const Text('标记完成'),
      content: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            '「${widget.title}」',
            maxLines: 1,
            overflow: TextOverflow.ellipsis,
          ),
          const SizedBox(height: 12),
          ListTile(
            contentPadding: EdgeInsets.zero,
            leading: const Icon(Icons.event_outlined, color: AppColors.muted),
            title: const Text('完成日期', style: TextStyle(fontSize: 14)),
            subtitle: Text(
              dateToJson(_date),
              style: const TextStyle(color: AppColors.inkSoft, fontSize: 12),
            ),
            onTap: () async {
              final now = DateTime.now();
              final value = await pickAppDate(
                context: context,
                initialDate: _date,
                firstDate: DateTime(1990),
                lastDate: now,
              );
              if (value != null && mounted) {
                setState(() => _date = value);
              }
            },
            trailing: AppDateFieldTrailing(
              firstDate: DateTime(1990),
              lastDate: DateTime.now(),
              onToday: (value) => setState(() => _date = value),
            ),
          ),
        ],
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.of(context).pop(),
          child: const Text('取消'),
        ),
        FilledButton(
          onPressed: () => Navigator.of(context).pop(_date),
          child: const Text('确认完成'),
        ),
      ],
    );
  }
}