todotxt_reminder/lib/main.dart

import 'package:flutter/material.dart';
import 'package:intl/date_symbol_data_local.dart';
import 'package:intl/intl_standalone.dart';
import 'package:nextcloud_reminder/homescreen.dart';


void main() {
  findSystemLocale().then((value) =>
    initializeDateFormatting(value).then((_) =>
    runApp(const TodoTxtReminderApp())
  ));
}

class TodoTxtReminderApp extends StatelessWidget {
  const TodoTxtReminderApp({super.key});
  static const primaryColor = Colors.pink;
  static const secondaryColor = Colors.amber;

  getInteractColor(Color a, Color b) {
    return (Set<MaterialState> states) {
      const Set<MaterialState> interactiveStates = <MaterialState>{
        MaterialState.pressed,
        MaterialState.hovered,
        MaterialState.focused,
      };
      if (states.any(interactiveStates.contains)) {
        return b;
      }
      return a;
    };
  }

  Color getColor(Set<MaterialState> states) {
    return getInteractColor(primaryColor, secondaryColor)(states);
  }

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    const inputDecorationTheme = InputDecorationTheme(border: OutlineInputBorder(), focusColor: secondaryColor);

    return MaterialApp(
      title: 'Todo.txt Reminder',
      theme: ThemeData(
        brightness: Brightness.light,
        colorScheme: ThemeData.light().colorScheme.copyWith(primary: primaryColor, secondary: secondaryColor, background: primaryColor.shade50),
        inputDecorationTheme: inputDecorationTheme,
        checkboxTheme: ThemeData.light().checkboxTheme.copyWith(
            fillColor: MaterialStateProperty.resolveWith(getColor),
            checkColor: MaterialStateProperty.resolveWith(getInteractColor(Colors.white,Colors.black))
        ),
      ),
      darkTheme: ThemeData(
        brightness: Brightness.dark,
        colorScheme: ThemeData.dark().colorScheme.copyWith(primary: primaryColor, secondary: secondaryColor, background: primaryColor.shade500.withAlpha(32)),
        inputDecorationTheme: inputDecorationTheme,
        checkboxTheme: ThemeData.dark().checkboxTheme.copyWith(
            fillColor: MaterialStateProperty.resolveWith(getColor),
            checkColor: MaterialStateProperty.resolveWith(getInteractColor(Colors.white,Colors.black))
        ),
      ),
      themeMode: ThemeMode.system,
      home: const HomeWidget(title: 'Todo.txt Reminder'),
    );
  }
}