main.dart

void main () {
  DateTime startDayShift = DateTime(2023, 7, 5, 8, 20); // 7月5日の8:20開始
  DateTime endDayShift = DateTime(2023, 7, 5, 18, 20); // 7月5日の18:20終了
  DateTime startNightShift = DateTime(2023, 7, 5, 20, 35); // 7月5日の20:35開始
  DateTime endNightShift = DateTime(2023, 7, 6, 5, 35); // 7月6日の5:35終了
  
  print("日勤");
  Duration totalDayShiftDuration = calculateTotalDuration(startDayShift, endDayShift, excludedRanges);
  int totalDayShiftDurationInMinutes = totalDayShiftDuration.inMinutes;
  print('昼勤計算結果 => $totalDayShiftDurationInMinutes 分');
  
  print("-----");
  
  print("夜勤");
  Duration totalNightShiftDuration = calculateTotalDuration(startNightShift, endNightShift, excludedRanges);
  int totalNightShiftDurationInMinutes = totalNightShiftDuration.inMinutes;
  print('夜勤計算結果 => $totalNightShiftDurationInMinutes 分');
}

List<TimeRange> excludedRanges = [
    // 日勤の除外時間
    TimeRange(startHour: 10, startMinute: 5, endHour: 10, endMinute: 15),
    TimeRange(startHour: 12, startMinute: 0, endHour: 13, endMinute: 15),
    TimeRange(startHour: 15, startMinute: 0, endHour: 15, endMinute: 10),
    TimeRange(startHour: 17, startMinute: 10, endHour: 17, endMinute: 20),
  
    // 夜勤の除外時間
    TimeRange(startHour: 22, startMinute: 30, endHour: 22, endMinute: 40),
    TimeRange(startHour: 24 + 0, startMinute: 30, endHour: 24 + 1, endMinute: 30),
    TimeRange(startHour: 24 + 3, startMinute: 0, endHour:  24 + 3, endMinute: 10),
    TimeRange(startHour: 24 + 4, startMinute: 30, endHour:  24 + 4, endMinute: 40),
];

Duration calculateTotalDuration(DateTime startTime, DateTime endTime, List<TimeRange> excludedRanges) {
  Duration totalDuration = endTime.difference(startTime);

  for (final range in excludedRanges) {
    DateTime rangeStartTime = DateTime(startTime.year, startTime.month, startTime.day, range.startHour, range.startMinute);
    DateTime rangeEndTime = DateTime(startTime.year, startTime.month, startTime.day, range.endHour, range.endMinute);

    if (rangeEndTime.isBefore(rangeStartTime)) {
      rangeEndTime = rangeEndTime.add(const Duration(days: 1));
    }
    
    if (rangeStartTime.isAfter(rangeEndTime)) {
      rangeStartTime = rangeStartTime.subtract(const Duration(days: 1));
    }

    if (rangeStartTime.isBefore(endTime) && rangeEndTime.isAfter(startTime)) {
      Duration excludedDuration = rangeEndTime.difference(rangeStartTime);
      totalDuration -= excludedDuration;
      print('この時間帯が除外されました: ${range.startHour.toString().padLeft(2, '0')}:${range.startMinute.toString().padLeft(2, '0')} - ${range.endHour.toString().padLeft(2, '0')}:${range.endMinute.toString().padLeft(2, '0')}');
    }
  }
  return totalDuration;
}


class TimeRange {
  final int startHour;
  final int startMinute;
  final int endHour;
  final int endMinute;

  TimeRange({
    required this.startHour,
    required this.startMinute,
    required this.endHour,
    required this.endMinute,
  });
}