how to use countdown timer in flutter?

I want to use a time countdown timer for date based on day, hour, minute and second. I found a code that does this for me.
This is the code:

import 'dart:async';
import 'package:flutter/material.dart';

class Time extends StatefulWidget {
  const Time({Key? key}) : super(key: key);

  @override
  State<Time> createState() => _TimeState();
}

final eventTime = DateTime.parse('2024-01-10 03:41:00');
class _TimeState extends State<Time> {

  static const duration = Duration(seconds: 1);
  int timeDiff = eventTime.difference(DateTime.now()).inSeconds;
  late Timer timer;
  bool isActive = true;

  void handleTick() {
    if (timeDiff > 0) {
      if (isActive) {
        setState(() {
          if (eventTime != DateTime.now()) {
            timeDiff = timeDiff - 1;
          } else {
            print('Times up!');
            //Do something
          }
        });
      }
    }
  }

  @override
  void dispose() {
    super.dispose();
  }

  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    timer = Timer.periodic(duration, (Timer t) {
      handleTick();
    });
    int days = timeDiff ~/ (24 * 60 * 60) % 24;
    int hours = timeDiff ~/ (60 * 60) % 24;
    int minutes = (timeDiff ~/ 60) % 60;
    int seconds = timeDiff % 60;
    return Scaffold(
        appBar: AppBar(
          backgroundColor: const Color(0x00fafafa),
          elevation: 0,
          leading: const BackButton(color: Colors.deepOrange,),
        ),
        body: SingleChildScrollView(
          child: Column(
            children: [
              Column(
                children: [
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      LabelText(
                          label: 'DAYS', value: days.toString().padLeft(2, '0')),
                      LabelText(
                          label: 'HRS', value: hours.toString().padLeft(2, '0')),
                      LabelText(
                          label: 'MIN', value: minutes.toString().padLeft(2, '0')),
                      LabelText(
                          label: 'SEC', value: seconds.toString().padLeft(2, '0')),
                    ],
                  ),
                ],
              ),
            ],
          ),
        )
    );
  }
}


class LabelText extends StatelessWidget {
  const LabelText({super.key, required this.label, required this.value});

  final String label;
  final String value;

  @override
  Widget build(BuildContext context) {
    return Container(
      margin: const EdgeInsets.symmetric(horizontal: 5),
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(25),
        color: Colors.grey,
      ),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          Text(
            value,
            style: const TextStyle(
                color: Colors.white, fontSize: 20, fontWeight: FontWeight.bold),
          ),
          Text(
            label,
            style: const TextStyle(
              color: Colors.white70,
            ),
          ),
        ],
      ),
    );
  }
}

But these codes cannot show the number of remaining days correctly.
I want it to show the number of days and hours left.
And another problem that exists is that the counting speed is very high and it is not compatible with real time