How to calculate the working hours in flutter using mongodb - node.js

Question

I want to calculate the working hours, my scenario is, when user login to the app and clicks on time in button that time will be stored in the database (I am using mongodb) and if user logout and then login again and then time in button should display the time at which user did last time, and then if user clicks on time out button then it should calculate the working hours, for example, if user time in at 9:10:35 AM and time out at 5:50:47 PM then the total working hours should be 9:40:13 , but from my logic of calculating total working hours it give me this 4:40:12.
Here is my code:
totalWorkingHours() {
print("working hours");
var totalWorkingMin;
var totalWorkingSec;
var totalWorkingHour;
var timeInHoursSplit;
var timeOutHoursSplit;
var timeInHours0;
var timeOutHours0;
List timeInHours;
List timeOutHours;
var inHour;
var outHour;
var inMin;
var outMin;
var inSec;
var outSec;
var flagMin = false;
var flagSec = false;
var defaultIn = " 00:00:00 PM";
var defaultOut = " 00:00:00 PM";
var data = {};
//here i am getting the time in and time out values and using api if in case user logout, and spliting it to get the hours, min and sec
if(workinghours=="0" && getapitimeout==""){
print("11");
timeInHoursSplit = defaultIn.split(' '); //18:35:00 PM
timeOutHoursSplit = defaultOut.split(' ');
}
else if (workinghours == "0" && getTimeInStatus == true) {
print("12");
timeInHoursSplit = gettimeinvalue.split(' '); //18:35:00 PM
timeOutHoursSplit = getapitimeout.split(' ');
}
//if logged in , did timein and timeout at once.
else if(gettimeinworkinghours=="0" && getapitimeout!=""){
print("13");
print(getapitimein);
print(getapitimeout);
timeInHoursSplit = getapitimein.split(' ');
timeOutHoursSplit = getapitimeout.split(' ');
}
//if not time in and time out yet
else {
print("14");
print(getapitimeout);
timeInHoursSplit = defaultIn.split(' ');
timeOutHoursSplit = defaultOut.split(' ');
}
print("1");
print(timeInHoursSplit); //[18:35:00, PM]
timeInHours0 = timeInHoursSplit[1]; //18:35:00
print("2");
print(timeInHours0);
timeOutHours0 = timeOutHoursSplit[1];
timeInHours = timeInHours0.split(':'); //[18, 35, 00]
print(timeInHours);
timeOutHours = timeOutHours0.split(':');
inHour = timeInHours[0];
outHour = timeOutHours[0];
inMin = timeInHours[1];
outMin = timeOutHours[1];
inSec=timeInHours[2];
outSec=timeOutHours[2];
// here i am calculating the hours
if (int.parse(inHour) > int.parse(outHour)) {
totalWorkingHour = int.parse(inHour) - int.parse(outHour);
print(totalWorkingHours);
} else {
totalWorkingHour = int.parse(outHour) - int.parse(outHour);
print(totalWorkingHours);
}
// here i am calculating the min
if (inMin != outMin) {
if (int.parse(outMin) > int.parse(inMin)) {
totalWorkingMin = int.parse(outMin) - int.parse(inMin);
flagMin = true;
} else if (int.parse(inMin) > int.parse(outMin)) {
totalWorkingMin = int.parse(inMin) - int.parse(outMin);
flagMin = true;
}
} else if (inMin == outMin) {
totalWorkingMin = int.parse(outMin) - int.parse(inMin);
flagMin = true;
}
// here i am calculating the sec
if (inSec != outSec) {
if (int.parse(outSec) > int.parse(inSec)) {
totalWorkingSec = int.parse(outSec) - int.parse(inSec);
flagSec = true;
} else if (int.parse(inSec) > int.parse(outSec)) {
totalWorkingSec = int.parse(inSec) - int.parse(outSec);
flagSec = true;
}
} else if (inSec == outSec) {
totalWorkingSec = int.parse(outSec) - int.parse(inSec);
flagSec = true;
}
//// here i am getting the totalworkinghours by concatenating the hours, min and sec
if (flagMin == true && flagSec==true) {
print("1 output");
totalTime = totalWorkingHour.toString() +":" +totalWorkingMin.toString() +":"+totalWorkingSec.toString();
print(totalTime);
return totalTime;
}
//cond 2
else if (flagMin == false && flagSec==false){
print("2 output");
totalTime = totalWorkingHour.toString() +":" +inMin.toString() + ":" +inSec.toString();
return totalTime;
}
//cond 3
else if (flagMin == false && flagSec == true) {
print("3 output");
totalTime = totalWorkingHour.toString() +":" +inMin.toString() ;
return totalTime;
}
//cond 4
else if (flagMin == true && flagSec == false) {
print("4 output");
totalTime = totalWorkingHour.toString() +":" +totalWorkingMin.toString() +":" +inSec.toString();
return totalTime;
}
}
Kindly please help how I can do this.