flutter_clock/lib/model/timer_data.dart

import 'package:shared_preferences/shared_preferences.dart';

/// A model class to store timer state data
class TimerData {
  static const String _startTimeKey = 'timer_start_time';
  static const String _endTimeKey = 'timer_end_time';
  static const String _pausedRemainingKey = 'timer_paused_remaining';
  static const String _isRunningKey = 'timer_is_running';
  static const String _isPausedKey = 'timer_is_paused';

  // Timer start time in milliseconds since epoch
  final int? startTime;
  
  // Timer end time in milliseconds since epoch
  final int? endTime;
  
  // Remaining seconds when timer was paused
  final int? pausedRemaining;
  
  // Whether timer is currently running
  final bool isRunning;
  
  // Whether timer is currently paused
  final bool isPaused;

  TimerData({
    this.startTime,
    this.endTime,
    this.pausedRemaining,
    this.isRunning = false,
    this.isPaused = false,
  });

  /// Save timer data to SharedPreferences
  Future<void> save() async {
    final prefs = await SharedPreferences.getInstance();
    
    if (startTime != null) {
      await prefs.setInt(_startTimeKey, startTime!);
    } else {
      await prefs.remove(_startTimeKey);
    }
    
    if (endTime != null) {
      await prefs.setInt(_endTimeKey, endTime!);
    } else {
      await prefs.remove(_endTimeKey);
    }
    
    if (pausedRemaining != null) {
      await prefs.setInt(_pausedRemainingKey, pausedRemaining!);
    } else {
      await prefs.remove(_pausedRemainingKey);
    }
    
    await prefs.setBool(_isRunningKey, isRunning);
    await prefs.setBool(_isPausedKey, isPaused);
  }

  /// Load timer data from SharedPreferences
  static Future<TimerData> load() async {
    final prefs = await SharedPreferences.getInstance();
    
    return TimerData(
      startTime: prefs.containsKey(_startTimeKey) ? prefs.getInt(_startTimeKey) : null,
      endTime: prefs.containsKey(_endTimeKey) ? prefs.getInt(_endTimeKey) : null,
      pausedRemaining: prefs.containsKey(_pausedRemainingKey) ? prefs.getInt(_pausedRemainingKey) : null,
      isRunning: prefs.getBool(_isRunningKey) ?? false,
      isPaused: prefs.getBool(_isPausedKey) ?? false,
    );
  }

  /// Calculate remaining seconds based on current time and end time
  int calculateRemainingSeconds() {
    if (isPaused && pausedRemaining != null) {
      return pausedRemaining!;
    }
    
    if (endTime != null) {
      final now = DateTime.now().millisecondsSinceEpoch;
      final remaining = (endTime! - now) ~/ 1000;
      return remaining > 0 ? remaining : 0;
    }
    
    return 0;
  }

  /// Create a copy of this timer data with modified properties
  TimerData copyWith({
    int? startTime,
    int? endTime,
    int? pausedRemaining,
    bool? isRunning,
    bool? isPaused,
  }) {
    return TimerData(
      startTime: startTime ?? this.startTime,
      endTime: endTime ?? this.endTime,
      pausedRemaining: pausedRemaining ?? this.pausedRemaining,
      isRunning: isRunning ?? this.isRunning,
      isPaused: isPaused ?? this.isPaused,
    );
  }
}