Flutter - check if the current time is in between a given hourly range

//checks if restaurant is open or closed 
// returns true if current time is in between given timestamps
//openTime HH:MMAM or HH:MMPM same for closedTime
bool checkRestaurentStatus(String openTime, String closedTime) {
    //NOTE: Time should be as given format only
    //10:00PM
    //10:00AM

    // 01:60PM ->13:60
    //Hrs:Min
    //if AM then its ok but if PM then? 12+time (12+10=22)

    TimeOfDay timeNow = TimeOfDay.now();
    String openHr = openTime.substring(0, 2);
    String openMin = openTime.substring(3, 5);
    String openAmPm = openTime.substring(5);
    TimeOfDay timeOpen;
    if (openAmPm == "AM") {
      //am case
      if (openHr == "12") {
        //if 12AM then time is 00
        timeOpen = TimeOfDay(hour: 00, minute: int.parse(openMin));
      } else {
        timeOpen =
            TimeOfDay(hour: int.parse(openHr), minute: int.parse(openMin));
      }
    } else {
      //pm case
      if (openHr == "12") {
//if 12PM means as it is
        timeOpen =
            TimeOfDay(hour: int.parse(openHr), minute: int.parse(openMin));
      } else {
//add +12 to conv time to 24hr format
        timeOpen =
            TimeOfDay(hour: int.parse(openHr) + 12, minute: int.parse(openMin));
      }
    }

    String closeHr = closedTime.substring(0, 2);
    String closeMin = closedTime.substring(3, 5);
    String closeAmPm = closedTime.substring(5);

    TimeOfDay timeClose;

    if (closeAmPm == "AM") {
      //am case
      if (closeHr == "12") {
        timeClose = TimeOfDay(hour: 0, minute: int.parse(closeMin));
      } else {
        timeClose =
            TimeOfDay(hour: int.parse(closeHr), minute: int.parse(closeMin));
      }
    } else {
      //pm case
      if (closeHr == "12") {
        timeClose =
            TimeOfDay(hour: int.parse(closeHr), minute: int.parse(closeMin));
      } else {
        timeClose = TimeOfDay(
            hour: int.parse(closeHr) + 12, minute: int.parse(closeMin));
      }
    }

    int nowInMinutes = timeNow.hour * 60 + timeNow.minute;
    int openTimeInMinutes = timeOpen.hour * 60 + timeOpen.minute;
    int closeTimeInMinutes = timeClose.hour * 60 + timeClose.minute;

//handling day change ie pm to am
    if ((closeTimeInMinutes - openTimeInMinutes) < 0) {
      closeTimeInMinutes = closeTimeInMinutes + 1440;
      if (nowInMinutes >= 0 && nowInMinutes < openTimeInMinutes) {
        nowInMinutes = nowInMinutes + 1440;
      }
      if (openTimeInMinutes < nowInMinutes &&
          nowInMinutes < closeTimeInMinutes) {
        return true;
      }
    } else if (openTimeInMinutes < nowInMinutes &&
        nowInMinutes < closeTimeInMinutes) {
      return true;
    }

    return false;

  }

 bool isValidTimeRange(TimeOfDay startTime, TimeOfDay endTime) {
    TimeOfDay now = TimeOfDay.now();
    return ((now.hour > startTime.hour) || (now.hour == startTime.hour && now.minute >= startTime.minute))
        && ((now.hour < endTime.hour) || (now.hour == endTime.hour && now.minute <= endTime.minute));
  }

As you have noticed, using DateTime in our case is not the best solution because it relies on the month/year/day. Instead, we can make use of the TimeOfDay class that does not rely on a specific day, but only on the time:

List<TimeOfDay> openingTimeRange = [TimeOfDay(hour: 2, minute: 30), TimeOfDay(hour: 15, minute: 45)]; // as an example
bool isOpen(List<TimeOfDay> openingTimeRange) {
   TimeOfDay now = TimeOfDay.now();
   return now.hour >= openingTimeRange[0].hour
      && now.minute >= openingTimeRange[0].minute
      && now.hour <= openingTimeRange[1].hour
      && now.minute <= openingTimeRange[1].minute;
}

I have a simple solution if your time format is in 24 hours. For that you don't require any external library.

bool _getStoreOpenStatus(String openTime, String closeTime) {
    bool result = false;

    DateTime now = DateTime.now();
    int nowHour = now.hour;
    int nowMin = now.minute;

    print('Now: H$nowHour M$nowMin');

    var openTimes = openTime.split(":");
    int openHour = int.parse(openTimes[0]);
    int openMin = int.parse(openTimes[1]);

    print('OpenTimes: H$openHour M$openMin');

    var closeTimes = closeTime.split(":");
    int closeHour = int.parse(closeTimes[0]);
    int closeMin = int.parse(closeTimes[1]);

    print('CloseTimes: H$closeHour M$closeMin');

    if(nowHour >= openHour && nowHour <= closeHour) {
      if(nowMin > openMin && nowMin < closeMin) result = true;
    }

    return result;
  }

If you use your time in the digital format [0..23] for hours, then you can convert the time to the amount of seconds that have past in that day. Do the same for the ranges you would like to check and see whether the current time past in seconds are between the two number ranges (in seconds):

TimeOfDay now = TimeOfDay.now(); // or DateTime object
TimeOfDay openingTime = TimeOfDay(hours: ??, minutes:??); // or leave as DateTime object
TimeOfDay closingTime = TimeOfDay(hours: ??, minutes:??); // or leave as DateTime object

int shopOpenTimeInSeconds = openingTime.hour * 60 + openingTime.minute;
int shopCloseTimeInSeconds = closingTime.hour * 60 + closingTime.minute;
int timeNowInSeconds = now.hour * 60 + now.minute;

if (shopOpenTimeInSeconds <= timeNowInSeconds &&
    timeNowInSeconds <= shopCloseTimeInSeconds) {
  // OPEN;
} else {
  // CLOSED;
}