// 📅 백품타 출석 달력(개인 스트릭 + 관리자 이벤트) 화면의 기능 담당 컨트롤러.
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:http/http.dart' as http;
import '../config.dart';

class StudyCalendarController extends ChangeNotifier {
  final String studentId;

  StudyCalendarController({required this.studentId});

  bool _isLoading = true;
  bool _isBusy = false;
  int _currentStreak = 0;
  int _longestStreak = 0;
  Set<String> _studiedDates = {};
  Map<String, dynamic> _events = {}; // date -> {title, description}
  DateTime _visibleMonth = DateTime.now();
  bool _disposed = false;

  bool get isLoading => _isLoading;
  bool get isBusy => _isBusy;
  int get currentStreak => _currentStreak;
  int get longestStreak => _longestStreak;
  Set<String> get studiedDates => _studiedDates;
  Map<String, dynamic> get events => _events;
  DateTime get visibleMonth => _visibleMonth;

  void _safeNotify() {
    if (!_disposed) notifyListeners();
  }

  @override
  void dispose() {
    _disposed = true;
    super.dispose();
  }

  Future<void> init() => refresh();

  Future<void> goToPreviousMonth() async {
    _visibleMonth = DateTime(_visibleMonth.year, _visibleMonth.month - 1);
    await refresh();
  }

  Future<void> goToNextMonth() async {
    _visibleMonth = DateTime(_visibleMonth.year, _visibleMonth.month + 1);
    await refresh();
  }

  Future<void> refresh() async {
    _isLoading = true;
    _safeNotify();
    await Future.wait([_fetchStreak(), _fetchEvents()]);
    _isLoading = false;
    _safeNotify();
  }

  Future<void> _fetchStreak() async {
    try {
      final response = await http.get(
        Uri.parse(
          '$baseUrl/api/study/streak?studentId=$studentId'
          '&year=${_visibleMonth.year}&month=${_visibleMonth.month}',
        ),
      );
      if (response.statusCode == 200) {
        final data = jsonDecode(utf8.decode(response.bodyBytes));
        _currentStreak = (data['currentStreak'] as num?)?.toInt() ?? 0;
        _longestStreak = (data['longestStreak'] as num?)?.toInt() ?? 0;
        _studiedDates = ((data['studiedDates'] as List<dynamic>?) ?? [])
            .map((d) => d.toString())
            .toSet();
      }
    } catch (_) {
      // 조용히 무시
    }
  }

  Future<void> _fetchEvents() async {
    try {
      final response = await http.get(
        Uri.parse(
          '$baseUrl/api/calendar/events?year=${_visibleMonth.year}&month=${_visibleMonth.month}',
        ),
      );
      if (response.statusCode == 200) {
        final data = jsonDecode(utf8.decode(response.bodyBytes));
        final List<dynamic> list = data['events'] ?? [];
        _events = {for (final e in list) e['date']: e};
      }
    } catch (_) {
      // 조용히 무시
    }
  }

  Future<(bool success, String message)> saveEvent({
    required String date,
    required String title,
    required String description,
    required String createdBy,
  }) async {
    _isBusy = true;
    _safeNotify();
    try {
      final response = await http.post(
        Uri.parse('$baseUrl/api/calendar/events'),
        headers: {"Content-Type": "application/json"},
        body: jsonEncode({
          "date": date,
          "title": title.trim(),
          "description": description.trim(),
          "createdBy": createdBy,
        }),
      );
      final result = jsonDecode(utf8.decode(response.bodyBytes));
      if (response.statusCode == 200 && result['status'] == 'success') {
        await _fetchEvents();
        return (true, '${result['message'] ?? '등록했습니다.'}');
      }
      return (false, '${result['message'] ?? '등록 실패'}');
    } catch (e) {
      return (false, '네트워크 에러: $e');
    } finally {
      _isBusy = false;
      _safeNotify();
    }
  }

  Future<(bool success, String message)> deleteEvent(String date) async {
    _isBusy = true;
    _safeNotify();
    try {
      final response = await http.delete(
        Uri.parse('$baseUrl/api/calendar/events/$date'),
      );
      final result = jsonDecode(utf8.decode(response.bodyBytes));
      if (response.statusCode == 200 && result['status'] == 'success') {
        await _fetchEvents();
        return (true, '${result['message'] ?? '삭제했습니다.'}');
      }
      return (false, '${result['message'] ?? '삭제 실패'}');
    } catch (e) {
      return (false, '네트워크 에러: $e');
    } finally {
      _isBusy = false;
      _safeNotify();
    }
  }
}