Recurring for month and week in Flutter - flutter

Question

I am trying to create a feature where I can transfer money by scheduling, so for that, I need a recurring option for the month and weak, And the problem that I face is, that if a user chooses the 31st of a month every month doesn't have the 31st, so the transaction should happen in that particular month's end date.
for example: If I start recurring date is 31st May 2022
no of transactions: 3
Current Output: Dates of transactions => 1st July 2022, 31st July 2022, 31st August 2022,
Correct Output: 30th June 2022, 31st July 2022, 31st August 2022,

Answer 1

Maybe something like I proposed here:
With lastDayOfMonth you could potentially do something like
extension AddMonth on DateTime {
DateTime addMonths([int amount = 1]) {
final plusXMonths = DateTime(year, month + amount, day);
final xMonthsAhead = DateTime(year, month + amount);
if (xMonthsAhead.lastDayOfMonth.compareTo(plusXMonths).isNegative) {
return xMonthsAhead.lastDayOfMonth;
} else {
return plusXMonths;
}
}
}
This proposition is based on this code that I created a PR for:
extension DateTimeLastFirstDay on DateTime {
/// Returns the Monday of this week
DateTime get firstDayOfWeek =>
isUtc ? DateTime.utc(year, month, day + 1 - weekday) : DateTime(year, month, day + 1 - weekday);
/// Returns the Sunday of this week
DateTime get lastDayOfWeek =>
isUtc ? DateTime.utc(year, month, day + 7 - weekday) : DateTime(year, month, day + 7 - weekday);
/// Returns the first day of this month
DateTime get firstDayOfMonth => isUtc ? DateTime.utc(year, month, 1) : DateTime(year, month, 1);
/// Returns the last day of this month (considers leap years)
DateTime get lastDayOfMonth => isUtc ? DateTime.utc(year, month + 1, 0) : DateTime(year, month + 1, 0);
/// Returns the first day of this year
DateTime get firstDayOfYear => isUtc ? DateTime.utc(year, 1, 1) : DateTime(year, 1, 1);
/// Returns the last day of this year
DateTime get lastDayOfYear => isUtc ? DateTime.utc(year, 12, 31) : DateTime(year, 12, 31);
}
Using the time package you could create a similar code for weeks.