Flutter : Get daily points system button error - flutter

Question

I made a function for users to get daily points (every 24 Hours). The function is linked with Firebase Firestore.
My problem is that if I close the app, relaunch it and click the triggering button ($checkPoints). It will add extra points to database even if the user did it less than 24 Hours ago !
Can you please check the code under and help me fix this?
import 'dart:convert';
import 'dart:math';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:http/http.dart' as http;
class Authfirestore {
final String uid;
int points;
var dateFromApitme;
String lastTimeGotPointsFromFirebase;
Authfirestore({this.uid, this.points});
Firestore _firestore = Firestore();
Future checkPoints() async {
await dateApi();
if (dateFromApitme != null ) {
try {
if (lastTimeGotPointsFromFirebase != dateFromApitme && dateFromApitme != null) {
await getData();
dynamic result = _firestore
.collection('users')
.document('Jm7bx8NOE9Nfx6P8S1wD')
.setData({
'points': points + 1,
'LastTimeGotPoints' :dateFromApitme,
});
await getData();
print(result.toString());
trackingData();
} else {
print('You toke your cridit ');
}
} catch (e) {
print('Error in cehckpoints $e');
}
}
}
Future trackingData() async {
await Firestore.instance
.collection('users')
.document('Jm7bx8NOE9Nfx6P8S1wD')
.collection('tracking')
.document(_randomString(20))
.setData({
'date': DateTime.now(),
});
}
Future getData() async {
await Firestore.instance
.collection('users')
.document('Jm7bx8NOE9Nfx6P8S1wD')
.get()
.then((DocumentSnapshot ds) {
points = ds.data['points'];
lastTimeGotPointsFromFirebase = ds.data['LastTimeGotPoints'];
print('number of points is $points');
});
}
String _randomString(int length) {
va
r rand = new Random();
var codeUnits = new List.generate(length, (index) {
return rand.nextInt(33) + 89;
});
return new String.fromCharCodes(codeUnits);
}
Future dateApi() async {
var response =
await http.get('http://worldtimeapi.org/api/timezone/Asia/Muscat');
if (response != null) {
var data0 = jsonDecode(response.body);
var data01 = data0['datetime'];
dateFromApitme = data01.substring(0, 9);
} else {
dateFromApitme = null;
print('Please Check Your internet');
}
}
}