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/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/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_models.dart';
import 'package:patbond_flutter/features/pets/pets_repository.dart';
import 'package:patbond_flutter/features/pets/weight_form_page.dart';

enum _ListPhase { loading, ready, error }

/// 体重历史列表页（T2-13）：cursor 分页（「加载更多」追加，末页收起），
/// 四态齐备；新记录经 [WeightFormPage] 录入后就地插入列表头。
///
/// 曝光埋点：每次进入首个成功加载上报一次
/// `health_record_viewed(recordType=weight, source=pet_detail)`
/// （工单口径：列表曝光；不随滚动逐条上报）。
class WeightRecordsPage extends StatefulWidget {
  const WeightRecordsPage({
    required this.repository,
    required this.petId,
    required this.canWrite,
    super.key,
    this.analytics,
    this.pageSize,
  });

  final PetsRepository repository;
  final String petId;

  /// owner/caregiver 可写；viewer 隐藏录入入口（40300 语义前置）。
  final bool canWrite;

  final HealthRecordAnalytics? analytics;

  /// 每页条数（测试注入小页验证分页；缺省走服务端默认 20）。
  final int? pageSize;

  @override
  State<WeightRecordsPage> createState() => _WeightRecordsPageState();
}

class _WeightRecordsPageState extends State<WeightRecordsPage> {
  _ListPhase _phase = _ListPhase.loading;
  List<WeightRecord> _records = const [];
  String? _nextCursor;
  bool _hasMore = false;
  bool _loadingMore = false;
  ApiException? _error;
  bool _viewedFired = false;

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

  Future<void> _loadFirstPage() async {
    setState(() {
      _phase = _ListPhase.loading;
      _error = null;
    });
    try {
      final page = await widget.repository.listWeights(
        widget.petId,
        limit: widget.pageSize,
      );
      if (!mounted) return;
      setState(() {
        _records = page.items;
        _nextCursor = page.nextCursor;
        _hasMore = page.hasMore;
        _phase = _ListPhase.ready;
      });
      if (!_viewedFired) {
        _viewedFired = true;
        widget.analytics?.viewed(
          recordType: HealthRecordType.weight,
          source: HealthRecordViewSource.petDetail,
        );
      }
    } on ApiException catch (error) {
      if (!mounted) return;
      setState(() {
        _error = error;
        _phase = _ListPhase.error;
      });
    }
  }

  Future<void> _loadMore() async {
    if (_loadingMore || !_hasMore) return;
    setState(() => _loadingMore = true);
    try {
      final page = await widget.repository.listWeights(
        widget.petId,
        limit: widget.pageSize,
        cursor: _nextCursor,
      );
      if (!mounted) return;
      setState(() {
        _records = [..._records, ...page.items];
        _nextCursor = page.nextCursor;
        _hasMore = page.hasMore;
      });
    } on ApiException catch (error) {
      if (!mounted) return;
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(SnackBar(content: Text(petLoadErrorMessage(error))));
    } finally {
      if (mounted) setState(() => _loadingMore = false);
    }
  }

  Future<void> _openCreate() async {
    final created = await Navigator.of(context).push<WeightRecord>(
      fadePageRoute(
        WeightFormPage(
          repository: widget.repository,
          petId: widget.petId,
          analytics: widget.analytics,
        ),
        // record_form：健康记录漏斗到达段页名（06 §1.6 / §2.2）。
        settings: RouteSettings(name: AnalyticsPageName.recordForm.pageName),
      ),
    );
    if (created != null && mounted) {
      setState(() {
        // 契约排序 measured_at DESC, id DESC：新记录通常最新，就地插头；
        // 补录历史日期的位置以下次刷新为准（服务端是唯一事实来源）。
        _records = [created, ..._records];
        if (_phase != _ListPhase.ready) _phase = _ListPhase.ready;
      });
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(const SnackBar(content: Text('已记录体重')));
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.transparent,
        elevation: 0,
        foregroundColor: AppColors.ink,
        title: const Text('体重记录'),
        centerTitle: true,
        titleTextStyle: const TextStyle(
          color: AppColors.ink,
          fontSize: 16,
          fontWeight: FontWeight.w800,
        ),
        actions: [
          if (widget.canWrite && _phase == _ListPhase.ready)
            IconButton(
              tooltip: '记录体重',
              onPressed: _openCreate,
              icon: const Icon(Icons.add),
            ),
        ],
      ),
      body: 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: _loadFirstPage,
                  child: const Text('重试'),
                ),
              ],
            ),
          ),
        ),
        _ListPhase.ready when _records.isEmpty => Center(
          child: SingleChildScrollView(
            child: EmptyStateIllustration(
              icon: Icons.monitor_weight_outlined,
              title: '还没有体重记录',
              description: '定期称重，看见毛孩子的成长曲线',
              ctaLabel: widget.canWrite ? '记录第一条' : null,
              onCtaPressed: widget.canWrite ? _openCreate : null,
            ),
          ),
        ),
        _ListPhase.ready => _list(),
      },
    );
  }

  Widget _list() {
    return RefreshIndicator(
      onRefresh: _loadFirstPage,
      child: ListView(
        padding: const EdgeInsets.fromLTRB(16, 8, 16, 30),
        children: [
          for (final record in _records) ...[
            _WeightTile(record: record),
            const SizedBox(height: 10),
          ],
          if (_hasMore)
            Center(
              child: _loadingMore
                  ? const Padding(
                      padding: EdgeInsets.all(12),
                      child: SizedBox(
                        width: 22,
                        height: 22,
                        child: CircularProgressIndicator(strokeWidth: 2),
                      ),
                    )
                  : TextButton(onPressed: _loadMore, child: const Text('加载更多')),
            ),
        ],
      ),
    );
  }
}

/// 体重条目：RecordTypeDot(体重) + 大数值（primaryDark w800）+
/// 日期/备注副行（05 §3.3 时间线条目形态的数值型变体）。
class _WeightTile extends StatelessWidget {
  const _WeightTile({required this.record});

  final WeightRecord record;

  @override
  Widget build(BuildContext context) {
    final meta = StringBuffer(formatMeasuredAt(record.measuredAt));
    if (record.note != null && record.note!.isNotEmpty) {
      meta.write(' · ${record.note}');
    }
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(14),
        child: Row(
          children: [
            const RecordTypeDot(
              type: RecordType.weight,
              size: RecordTypeDotSize.md,
            ),
            const SizedBox(width: 12),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    '${formatWeightKg(record.weightKg)} kg',
                    style: const TextStyle(
                      color: AppColors.primaryDark,
                      fontSize: 15,
                      fontWeight: FontWeight.w800,
                    ),
                  ),
                  const SizedBox(height: 4),
                  Text(
                    meta.toString(),
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: const TextStyle(
                      color: AppColors.inkSoft,
                      fontSize: 12,
                    ),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

/// 称重时刻展示：本地时区 `YYYY-MM-DD HH:mm`。
String formatMeasuredAt(DateTime measuredAt) {
  final local = measuredAt.toLocal();
  final h = local.hour.toString().padLeft(2, '0');
  final min = local.minute.toString().padLeft(2, '0');
  return '${dateToJson(local)} $h:$min';
}