import 'package:flutter/material.dart';
import 'package:flutter/semantics.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/app_text_field.dart';
import 'package:patbond_flutter/core/widgets/inline_error_banner.dart';
import 'package:patbond_flutter/core/widgets/primary_button.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_exceptions.dart';
import 'package:patbond_flutter/features/pets/pet_models.dart';
import 'package:patbond_flutter/features/pets/pets_repository.dart';

/// 体重录入表单页（T2-13）。
///
/// - `weightKg` 前端校验对齐契约：(0, 500]、最多两位小数；后端 40000 兜底。
/// - 称重时间默认「现在」，可回选日期（非今日取当日 12:00，保持
///   measured_at DESC 排序直觉）；提交前转 UTC，ISO 8601 带 Z 上送。
/// - 错误分层沿用登录纵切：字段 errorText / InlineErrorBanner / SnackBar。
/// - 埋点：首次输入 health_record_create_started(recordType=weight)，
///   成功/失败按 06 §1.4 经 [HealthRecordAnalytics] 上报。
class WeightFormPage extends StatefulWidget {
  const WeightFormPage({
    required this.repository,
    required this.petId,
    super.key,
    this.analytics,
    this.entryPoint = HealthRecordEntryPoint.recordList,
  });

  final PetsRepository repository;
  final String petId;
  final HealthRecordAnalytics? analytics;
  final HealthRecordEntryPoint entryPoint;

  @override
  State<WeightFormPage> createState() => _WeightFormPageState();
}

class _WeightFormPageState extends State<WeightFormPage> {
  final _weightCtrl = TextEditingController();
  final _noteCtrl = TextEditingController();

  DateTime _measuredDate = DateTime.now();
  String? _weightError;
  String? _formError;
  bool _submitting = false;

  bool _startedFired = false;
  int _attemptSeq = 0;
  late final DateTime _openedAt;

  @override
  void initState() {
    super.initState();
    _openedAt = DateTime.now();
  }

  @override
  void dispose() {
    _weightCtrl.dispose();
    _noteCtrl.dispose();
    super.dispose();
  }

  void _markStarted() {
    if (_startedFired) return;
    _startedFired = true;
    widget.analytics?.createStarted(
      recordType: HealthRecordType.weight,
      entryPoint: widget.entryPoint,
    );
  }

  void _trackFailed(HealthRecordFailureReason reason, [int? errorCode]) {
    widget.analytics?.createFailed(
      recordType: HealthRecordType.weight,
      reason: reason,
      attemptSeq: _attemptSeq,
      errorCode: errorCode,
    );
  }

  String? _validateWeight() {
    final text = _weightCtrl.text.trim();
    if (text.isEmpty) return '请输入体重';
    if (parseWeightKgInput(text) == null) {
      return '体重需大于 0 且不超过 500 公斤，最多两位小数';
    }
    return null;
  }

  void _showFormError(String message) {
    setState(() => _formError = message);
    SemanticsService.sendAnnouncement(
      View.of(context),
      message,
      TextDirection.ltr,
    );
  }

  /// 称重时刻：今日取此刻，历史日期取当日 12:00（本地），提交前转 UTC。
  DateTime _measuredAt() {
    final now = DateTime.now();
    final sameDay =
        _measuredDate.year == now.year &&
        _measuredDate.month == now.month &&
        _measuredDate.day == now.day;
    final local = sameDay
        ? now
        : DateTime(
            _measuredDate.year,
            _measuredDate.month,
            _measuredDate.day,
            12,
          );
    return local.toUtc();
  }

  Future<void> _submit() async {
    if (_submitting) return;
    _attemptSeq++;
    final weightError = _validateWeight();
    if (weightError != null) {
      setState(() => _weightError = weightError);
      _trackFailed(HealthRecordFailureReason.validationError);
      return;
    }

    setState(() {
      _submitting = true;
      _formError = null;
    });
    try {
      final note = _noteCtrl.text.trim();
      final record = await widget.repository.createWeight(
        widget.petId,
        CreateWeightRequest(
          weightKg: parseWeightKgInput(_weightCtrl.text)!,
          measuredAt: _measuredAt(),
          note: note.isEmpty ? null : note,
        ),
      );
      widget.analytics?.createSucceeded(
        recordType: HealthRecordType.weight,
        durationMs: DateTime.now().difference(_openedAt).inMilliseconds,
      );
      if (mounted) Navigator.of(context).pop(record);
    } on PetAccessDeniedException {
      if (!mounted) return;
      _showFormError('你没有权限为该宠物添加记录');
      _trackFailed(HealthRecordFailureReason.permissionDenied, 40300);
    } on PetNotFoundException {
      if (!mounted) return;
      final navigator = Navigator.of(context);
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(const SnackBar(content: Text('宠物不存在或已被删除')));
      _trackFailed(HealthRecordFailureReason.notFound, 40401);
      navigator.pop();
    } on ApiRateLimitException {
      if (!mounted) return;
      _showFormError('操作过于频繁，请稍后再试');
      _trackFailed(HealthRecordFailureReason.rateLimited);
    } on ApiBusinessException catch (error) {
      if (!mounted) return;
      final isParam = error.code == ApiCodes.paramError;
      _showFormError(isParam ? '请检查填写内容后重试' : '保存失败，请稍后重试');
      _trackFailed(
        isParam
            ? HealthRecordFailureReason.validationError
            : HealthRecordFailureReason.serverError,
        error.code,
      );
    } on ApiNetworkException {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: const Text('网络异常，请检查网络后重试'),
          action: SnackBarAction(label: '重试', onPressed: _submit),
        ),
      );
      _trackFailed(HealthRecordFailureReason.networkError);
    } on SessionExpiredException {
      // 会话失效：认证状态机自动回登录页。
    } finally {
      if (mounted) setState(() => _submitting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.transparent,
        elevation: 0,
        foregroundColor: AppColors.ink,
        title: const Text('记录体重'),
        centerTitle: true,
        titleTextStyle: const TextStyle(
          color: AppColors.ink,
          fontSize: 16,
          fontWeight: FontWeight.w800,
        ),
      ),
      body: SafeArea(
        child: ListView(
          padding: const EdgeInsets.fromLTRB(20, 8, 20, 30),
          children: [
            AppTextField(
              label: '体重（公斤）',
              controller: _weightCtrl,
              prefixIcon: Icons.monitor_weight_outlined,
              errorText: _weightError,
              helperText: '大于 0 且不超过 500，最多两位小数',
              enabled: !_submitting,
              keyboardType: const TextInputType.numberWithOptions(
                decimal: true,
              ),
              textInputAction: TextInputAction.next,
              onChanged: (_) {
                _markStarted();
                if (_weightError != null || _formError != null) {
                  setState(() {
                    _weightError = null;
                    _formError = null;
                  });
                }
              },
            ),
            const SizedBox(height: 14),
            ListTile(
              shape: RoundedRectangleBorder(
                side: const BorderSide(color: AppColors.border),
                borderRadius: BorderRadius.circular(AppRadius.lg),
              ),
              tileColor: AppColors.surface,
              leading: const Icon(Icons.event_outlined, color: AppColors.muted),
              title: const Text('称重日期', style: TextStyle(fontSize: 14)),
              subtitle: Text(
                dateToJson(_measuredDate),
                style: const TextStyle(color: AppColors.inkSoft, fontSize: 12),
              ),
              trailing: AppDateFieldTrailing(
                firstDate: DateTime(1990),
                lastDate: DateTime.now(),
                enabled: !_submitting,
                onToday: (value) {
                  _markStarted();
                  setState(() => _measuredDate = value);
                },
              ),
              enabled: !_submitting,
              onTap: () async {
                final now = DateTime.now();
                final value = await pickAppDate(
                  context: context,
                  initialDate: _measuredDate,
                  firstDate: DateTime(1990),
                  lastDate: now,
                );
                if (value != null && mounted) {
                  _markStarted();
                  setState(() => _measuredDate = value);
                }
              },
            ),
            const SizedBox(height: 14),
            AppTextField(
              label: '备注（可选，如：饭后称重）',
              controller: _noteCtrl,
              prefixIcon: Icons.sticky_note_2_outlined,
              enabled: !_submitting,
              textInputAction: TextInputAction.done,
              onChanged: (_) => _markStarted(),
              onSubmitted: (_) => _submit(),
            ),
            if (_formError != null) ...[
              const SizedBox(height: 16),
              InlineErrorBanner(message: _formError!),
            ],
            const SizedBox(height: 24),
            PrimaryButton(
              label: '保存记录',
              isLoading: _submitting,
              onPressed: _submit,
            ),
          ],
        ),
      ),
    );
  }
}