Example for extending DateTime

tabeta_date_time.dart

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:intl/intl.dart';

/// Just a normal [DateTime] with helper functions
class TabetaDateTime extends DateTime {
  TabetaDateTime(int year,
      [int month = 1,
      int day = 1,
      int hour = 0,
      int minute = 0,
      int second = 0,
      int millisecond = 0,
      int microsecond = 0])
      : super(year, month, day, hour, minute, second, millisecond, microsecond);

  TabetaDateTime.utc(int year,
      [int month = 1,
      int day = 1,
      int hour = 0,
      int minute = 0,
      int second = 0,
      int millisecond = 0,
      int microsecond = 0])
      : super.utc(
            year, month, day, hour, minute, second, millisecond, microsecond);

  TabetaDateTime.now() : super.now();

  TabetaDateTime.fromDateTime(DateTime dateTime)
      : super(
          dateTime.year,
          dateTime.month,
          dateTime.day,
          dateTime.hour,
          dateTime.minute,
          dateTime.second,
          dateTime.millisecond,
          dateTime.microsecond,
        );

  factory TabetaDateTime.fromTimestamp(Timestamp timestamp) {
    return TabetaDateTime.fromDateTime(timestamp.toDate());
  }

  factory TabetaDateTime.fromData(dynamic data) {
    return TabetaDateTime.fromTimestamp(data as Timestamp);
  }

  DateTime toDateTime() {
    return DateTime(
        year, month, day, hour, minute, second, millisecond, microsecond);
  }

  Timestamp toTimestamp() {
    return Timestamp.fromDate(this);
  }

  TabetaDateTime startOfDay() {
    return TabetaDateTime(year, month, day);
  }

  TabetaDateTime endOfDay() {
    return TabetaDateTime(year, month, day, 23, 59, 59);
  }

  TabetaDateTime startOfNextDay() {
    return TabetaDateTime(year, month, day + 1);
  }

  TabetaDateTime yesterday() {
    return TabetaDateTime.fromDateTime(subtract(const Duration(days: 1)));
  }

  TabetaDateTime tomorrow() {
    return TabetaDateTime.fromDateTime(add(const Duration(days: 1)));
  }

  TabetaDateTime lastWeek() {
    return TabetaDateTime.fromDateTime(subtract(const Duration(days: 7)));
  }

  TabetaDateTime lastMonth() {
    return TabetaDateTime.fromDateTime(subtract(const Duration(days: 30)));
  }

  String formatM() {
    return DateFormat.M().format(this);
  }

  String formatMd() {
    return DateFormat.Md().format(this);
  }

  String formatHm() {
    return DateFormat.Hm().format(this);
  }

  bool isToday() {
    return isSameDay(TabetaDateTime.now());
  }

  bool isYesterday() {
    return isSameDay(TabetaDateTime.now().yesterday());
  }

  bool isSameDay(DateTime dateTime) {
    final tabetaDateTime = TabetaDateTime.fromDateTime(dateTime);
    return isAfter(tabetaDateTime.startOfDay()) &&
        isBefore(tabetaDateTime.endOfDay());
  }

  bool isAfterOrSame(DateTime other) {
    return isAfter(other) || isAtSameMomentAs(other);
  }

  bool isBeforeOrSame(DateTime other) {
    return isBefore(other) || isAtSameMomentAs(other);
  }

  TabetaDateTime startOfWeek() {
    return TabetaDateTime.fromDateTime(
      subtract(Duration(days: weekday - 1)),
    ).startOfDay();
  }

  TabetaDateTime endOfWeek() {
    return TabetaDateTime.fromDateTime(add(Duration(days: 7 - weekday)))
        .endOfDay();
  }

  TabetaDateTime startOfMonth() {
    return TabetaDateTime(
      year,
      month,
      1,
      0,
      0,
      0,
      0,
      0,
    );
  }

  TabetaDateTime endOfMonth() {
    final endOfMonth = TabetaDateTime(
      year,
      month + 1,
      1,
      0,
      0,
      0,
      0,
      0,
    ).subtract(const Duration(days: 1));

    return TabetaDateTime.fromDateTime(endOfMonth);
  }
}