// features/challenge/add/add_challenge_screen.dart
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:intl/intl.dart';
import 'package:japp_flutter/core/models/challenge_model.dart';
import 'package:japp_flutter/features/challenge/view_models/challenge_add_vm.dart';

class AddChallengeScreen extends ConsumerWidget {
  const AddChallengeScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final challengeState = ref.watch(addChallengeProvider);
    final theme = Theme.of(context);

    return Scaffold(
      appBar: AppBar(
        title: const Text('创建新挑战'),
        actions: [
          IconButton(
            icon: const Icon(Icons.check),
            onPressed: () async {
              await ref.read(addChallengeProvider.notifier).submitChallenge();
              if (context.mounted) Navigator.pop(context);
            },
            tooltip: '提交',
          ),
        ],
      ),
      body: challengeState.when(
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (error, _) => Center(child: Text('错误: $error')),
        data: (challenge) => _BuildForm(challenge: challenge),
      ),
    );
  }
}

class _BuildForm extends ConsumerWidget {
  final ChallengeModel challenge;

  const _BuildForm({required this.challenge});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return SingleChildScrollView(
      padding: const EdgeInsets.all(16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          _TitleField(initialValue: challenge.title),
          const SizedBox(height: 24),
          _DateRangeField(
            startDate: challenge.startDate,
            endDate: challenge.endDate,
          ),
          const SizedBox(height: 24),
          _DifficultySelector(currentDifficulty: challenge.difficulty),
          const SizedBox(height: 24),
          _DescriptionField(initialValue: challenge.description),
        ],
      ),
    );
  }
}

class _TitleField extends ConsumerWidget {
  final String initialValue;

  const _TitleField({required this.initialValue});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return TextFormField(
      initialValue: initialValue,
      decoration: const InputDecoration(
        labelText: '挑战标题*',
        border: OutlineInputBorder(),
      ),
      onChanged: (value) => ref.read(addChallengeProvider.notifier).updateTitle(value),
    );
  }
}

class _DescriptionField extends ConsumerWidget {
  final String initialValue;

  const _DescriptionField({required this.initialValue});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return TextFormField(
      initialValue: initialValue,
      decoration: const InputDecoration(
        labelText: '挑战描述',
        border: OutlineInputBorder(),
        alignLabelWithHint: true,
      ),
      maxLines: 5,
      onChanged: (value) => ref.read(addChallengeProvider.notifier).updateDescription(value),
    );
  }
}

class _DifficultySelector extends ConsumerWidget {
  final String currentDifficulty;
  static const difficulties = ['简单', '中等', '困难'];

  const _DifficultySelector({required this.currentDifficulty});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Text('难度级别*', style: TextStyle(fontSize: 16)),
        const SizedBox(height: 8),
        Wrap(
          spacing: 8,
          children: difficulties.map((level) {
            return ChoiceChip(
              label: Text(level),
              selected: currentDifficulty == level,
              onSelected: (selected) {
                if (selected) {
                  ref.read(addChallengeProvider.notifier).updateDifficulty(level);
                }
              },
            );
          }).toList(),
        ),
      ],
    );
  }
}

class _DateRangeField extends ConsumerWidget {
  final DateTime startDate;
  final DateTime endDate;

  const _DateRangeField({
    required this.startDate,
    required this.endDate,
  });

  Future<void> _selectDate(BuildContext context, bool isStartDate, WidgetRef ref) async {
    final initialDate = isStartDate ? startDate : endDate;
    final picked = await showDatePicker(
      context: context,
      initialDate: initialDate,
      firstDate: DateTime.now(),
      lastDate: DateTime(2100),
    );

    if (picked != null) {
      final newStart = isStartDate ? picked : startDate;
      final newEnd = isStartDate ? endDate : picked;
      ref.read(addChallengeProvider.notifier).updateDateRange(newStart, newEnd);
    }
  }

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Text('挑战周期*', style: TextStyle(fontSize: 16)),
        const SizedBox(height: 8),
        Row(
          children: [
            Expanded(
              child: OutlinedButton(
                onPressed: () => _selectDate(context, true, ref),
                child: Text(DateFormat('yyyy/MM/dd').format(startDate)),
              ),
            ),
            const Padding(
              padding: EdgeInsets.symmetric(horizontal: 8),
              child: Text('至'),
            ),
            Expanded(
              child: OutlinedButton(
                onPressed: () => _selectDate(context, false, ref),
                child: Text(DateFormat('yyyy/MM/dd').format(endDate)),
              ),
            ),
          ],
        ),
        const SizedBox(height: 4),
        Text(
          '总天数: ${endDate.difference(startDate).inDays}天',
          style: const TextStyle(color: Colors.grey),
        ),
      ],
    );
  }
}