// ⏱️ 우리 학교 전용 "백품타" 공부 타이머 화면의 기능(서버 통신/상태) 담당 컨트롤러.
import 'dart:async';
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:http/http.dart' as http;
import '../config.dart';

class StudyTimerController extends ChangeNotifier {
  final String studentId;
  final String studentName;

  StudyTimerController({required this.studentId, required this.studentName});

  bool _isLoading = true;
  bool _isBusy = false; // 시작/종료 버튼 눌러서 서버 응답 기다리는 중
  bool _isRunning = false;
  DateTime? _startTime;
  int _todaySeconds = 0;
  int _weekSeconds = 0;
  int _totalSeconds = 0;
  Timer? _ticker;
  bool _disposed = false;

  bool get isLoading => _isLoading;
  bool get isBusy => _isBusy;
  bool get isRunning => _isRunning;

  /// 지금 진행 중인 세션까지 포함한 "오늘" 누적 초. 실시간으로 똑딱거린다.
  int get todaySecondsLive =>
      _todaySeconds + (_isRunning ? _liveElapsedSeconds : 0);
  int get weekSecondsLive =>
      _weekSeconds + (_isRunning ? _liveElapsedSeconds : 0);
  int get totalSecondsLive =>
      _totalSeconds + (_isRunning ? _liveElapsedSeconds : 0);

  /// 지금 세션 하나만의 경과 시간(타이머 화면 큰 숫자용).
  int get _liveElapsedSeconds {
    if (_startTime == null) return 0;
    final diff = DateTime.now().difference(_startTime!).inSeconds;
    return diff > 0 ? diff : 0;
  }

  int get liveElapsedSeconds => _liveElapsedSeconds;

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

  Future<void> init() async {
    await _fetchStatus();
  }

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

  Future<void> _fetchStatus() async {
    try {
      final response = await http.get(
        Uri.parse('$baseUrl/api/study/status?studentId=$studentId'),
      );
      if (response.statusCode == 200) {
        final data = jsonDecode(utf8.decode(response.bodyBytes));
        _isRunning = data['isRunning'] == true;
        _startTime = data['startTime'] != null
            ? DateTime.tryParse(data['startTime'])
            : null;
        _todaySeconds = (data['todaySeconds'] as num?)?.toInt() ?? 0;
        _weekSeconds = (data['weekSeconds'] as num?)?.toInt() ?? 0;
        _totalSeconds = (data['totalSeconds'] as num?)?.toInt() ?? 0;
        _restartTickerIfNeeded();
      }
    } catch (_) {
      // 조용히 무시 - 마지막으로 알던 상태를 유지한다.
    } finally {
      _isLoading = false;
      _safeNotify();
    }
  }

  void _restartTickerIfNeeded() {
    _ticker?.cancel();
    if (_isRunning) {
      _ticker = Timer.periodic(
        const Duration(seconds: 1),
        (_) => _safeNotify(),
      );
    }
  }

  Future<(bool success, String message)> start() async {
    _isBusy = true;
    _safeNotify();
    try {
      final response = await http.post(
        Uri.parse('$baseUrl/api/study/start'),
        headers: {"Content-Type": "application/json"},
        body: jsonEncode({"studentId": studentId, "studentName": studentName}),
      );
      final result = jsonDecode(utf8.decode(response.bodyBytes));
      if (response.statusCode == 200 && result['status'] == 'success') {
        _isRunning = true;
        _startTime = DateTime.tryParse(result['startTime']);
        _restartTickerIfNeeded();
        return (true, '공부를 시작했습니다.');
      }
      return (false, '${result['message'] ?? '공부 시작 실패'}');
    } catch (e) {
      return (false, '네트워크 에러: $e');
    } finally {
      _isBusy = false;
      _safeNotify();
    }
  }

  Future<(bool success, String message)> stop() async {
    _isBusy = true;
    _safeNotify();
    try {
      final response = await http.post(
        Uri.parse('$baseUrl/api/study/stop'),
        headers: {"Content-Type": "application/json"},
        body: jsonEncode({"studentId": studentId}),
      );
      final result = jsonDecode(utf8.decode(response.bodyBytes));
      if (response.statusCode == 200 && result['status'] == 'success') {
        _isRunning = false;
        _startTime = null;
        _ticker?.cancel();
        await _fetchStatus(); // 오늘/이번주/전체 합계를 서버 값으로 다시 맞춘다.
        final minutes =
            ((result['durationSeconds'] as num?)?.toInt() ?? 0) ~/ 60;
        return (true, '이번 공부 시간: $minutes분 기록 완료!');
      }
      return (false, '${result['message'] ?? '공부 종료 실패'}');
    } catch (e) {
      return (false, '네트워크 에러: $e');
    } finally {
      _isBusy = false;
      _safeNotify();
    }
  }
}