import 'dart:math';
import 'package:flutter/material.dart';
import 'package:service_api/service_api.dart';
import 'package:service_api/models/assessment_data.dart'; 

class AssessmentScreen extends StatefulWidget {
  const AssessmentScreen({super.key});

  @override
  State<AssessmentScreen> createState() => _AssessmentScreenState();
}

class _AssessmentScreenState extends State<AssessmentScreen> {
  final Map<String, bool> _answers = {};
  final PageController _pageController = PageController();
  int _currentPage = 0;

  late final Map<CognitiveArea, List<AssessmentQuestion>> _dailyQuestions;
  late final List<CognitiveArea> _areaKeys;

  @override
  void initState() {
    super.initState();
    _dailyQuestions = _generateDailyQuestions();
    _areaKeys = _dailyQuestions.keys.toList();
  }

  /// [핵심 로직] 전체 문제 풀에서 영역별로 8개씩 랜덤 추출 (총 32문항)
  Map<CognitiveArea, List<AssessmentQuestion>> _generateDailyQuestions() {
    final random = Random();
    Map<CognitiveArea, List<AssessmentQuestion>> grouped = {};
    
    // 1. 전체 질문 분류
    Map<CognitiveArea, List<AssessmentQuestion>> pool = {};
    for (var q in rawAssessmentQuestions) {
      if (!pool.containsKey(q.area)) pool[q.area] = [];
      pool[q.area]!.add(q);
    }

    // 2. 각 영역에서 랜덤하게 8문제씩 추출 (총 32문제)
    // (데이터가 부족할 경우를 대비해 take 사용)
    pool.forEach((area, questions) {
      var shuffled = List<AssessmentQuestion>.from(questions)..shuffle(random);
      grouped[area] = shuffled.take(8).toList(); // 👈 8개로 설정
    });

    return grouped;
  }

  void _submitResult() async {
    // 1. 점수 계산
    Map<CognitiveArea, int> scores = {};
    int totalYesCount = 0;
    
    _dailyQuestions.forEach((area, questions) {
      int areaScore = 0;
      for (var q in questions) {
        if (_answers[q.id] == true) {
          areaScore++;
          totalYesCount++;
        }
      }
      scores[area] = areaScore;
    });

    // 2. 히스토리 저장
    final identityService = IdentityService();
    await identityService.saveAssessmentResult(scores); 

    if (!mounted) return;

    // 3. 결과 알림 (기준: 32문항 중 12개 이상이면 주의)
    String message = "진단 결과가 기록되었습니다.";
    if (totalYesCount >= 12) {
      message += "\n\n주의가 필요한 항목이 다수 확인되었습니다.\n($totalYesCount/32개 해당)\n꾸준한 훈련을 권장합니다.";
    } else {
      message += "\n\n현재 양호한 상태입니다.\n이 상태를 유지하기 위해 매일 훈련하세요!";
    }

    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (ctx) => AlertDialog(
        title: const Text('진단 완료'),
        content: Text(message),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.pop(ctx);
              Navigator.pop(context, true);
            },
            child: const Text('확인'),
          ),
        ],
      ),
    );
  }

  String _getAreaTitle(CognitiveArea area) {
    switch (area) {
      case CognitiveArea.memory: return "1. 기억력 체크";
      case CognitiveArea.perception: return "2. 시공간/지남력 체크";
      case CognitiveArea.calculation: return "3. 계산력/판단력 체크";
      case CognitiveArea.attention: return "4. 주의력/집행기능 체크";
      case CognitiveArea.language: return "5. 언어/구성 능력";
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('자가 진단 체크리스트'),
        centerTitle: true,
        bottom: PreferredSize(
          preferredSize: const Size.fromHeight(4.0),
          child: LinearProgressIndicator(
            value: (_currentPage + 1) / _areaKeys.length,
            backgroundColor: Colors.grey[200],
            valueColor: AlwaysStoppedAnimation<Color>(Theme.of(context).primaryColor),
          ),
        ),
      ),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.all(16.0),
            child: Text(
              _getAreaTitle(_areaKeys[_currentPage]),
              style: const TextStyle(fontSize: 22, fontWeight: FontWeight.bold),
            ),
          ),
          Expanded(
            child: PageView.builder(
              controller: _pageController,
              physics: const NeverScrollableScrollPhysics(),
              itemCount: _areaKeys.length,
              onPageChanged: (idx) {
                setState(() { _currentPage = idx; });
              },
              itemBuilder: (context, index) {
                final area = _areaKeys[index];
                final questions = _dailyQuestions[area]!;
                
                return ListView.separated(
                  padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
                  itemCount: questions.length,
                  separatorBuilder: (c, i) => const Divider(height: 1),
                  itemBuilder: (context, qIndex) {
                    final q = questions[qIndex];
                    final bool isChecked = _answers[q.id] ?? false;

                    return CheckboxListTile(
                      title: Text(
                        q.text, 
                        style: TextStyle(
                          fontSize: 16,
                          color: isChecked ? Colors.black : Colors.grey[800],
                          fontWeight: isChecked ? FontWeight.w600 : FontWeight.normal,
                        ),
                      ),
                      value: isChecked,
                      activeColor: Colors.redAccent,
                      onChanged: (val) {
                        setState(() { _answers[q.id] = val!; });
                      },
                    );
                  },
                );
              },
            ),
          ),
          Padding(
            padding: const EdgeInsets.all(16.0),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                if (_currentPage > 0)
                  ElevatedButton.icon(
                    onPressed: () => _pageController.previousPage(
                      duration: const Duration(milliseconds: 300), 
                      curve: Curves.easeInOut
                    ),
                    icon: const Icon(Icons.arrow_back),
                    label: const Text('이전'),
                    style: ElevatedButton.styleFrom(
                      padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 12),
                    ),
                  )
                else
                  const SizedBox(width: 90),

                Text(
                  "${_currentPage + 1} / ${_areaKeys.length}",
                  style: const TextStyle(fontWeight: FontWeight.bold, fontSize: 16),
                ),

                if (_currentPage < _areaKeys.length - 1)
                  ElevatedButton.icon(
                    onPressed: () => _pageController.nextPage(
                      duration: const Duration(milliseconds: 300), 
                      curve: Curves.easeInOut
                    ),
                    icon: const Icon(Icons.arrow_forward),
                    label: const Text('다음'),
                    style: ElevatedButton.styleFrom(
                      padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 12),
                    ),
                  )
                else
                  ElevatedButton.icon(
                    style: ElevatedButton.styleFrom(
                      backgroundColor: Colors.blueAccent,
                      foregroundColor: Colors.white,
                      padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 12),
                    ),
                    onPressed: _submitResult,
                    icon: const Icon(Icons.check),
                    label: const Text('결과 제출'),
                  ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}