Azure Bicep Function to calculate the StartDateTime (Azure Update Manager maintenance configuration)

StartDateTimeCalculator.bicep

@description('Custom start date for maintenance window. If not provided, current start date will be used. Format: yyyy-MM-dd')
param maintenanceStartDate string = ''
param currentStartDate string = utcNow('yyyy-MM-dd 00:00')

/* Due to limitations of the Bicep language, the error "StartDateTime should be after 15 minutes of creation" may occur.
To avoid this error, the start date is calculated as the next day. The following code is used to calculate the next day.
If the date is 28, the next day will be 01 next month. February has only 28 days, and 28 was taken just because of it. */
func calculateStartDate(currentStartDate string) object => {
  day: int(take(skip(currentStartDate, 8), 2)) < 28 ? string(int(take(skip(currentStartDate, 8), 2)) + 1) : '01'
  month: int(take(skip(currentStartDate, 8), 2)) < 28
    ? int(take(skip(currentStartDate, 5), 2)) <= 12 ? take(skip(currentStartDate, 5), 2) : '01'
    : int(take(skip(currentStartDate, 5), 2)) + 1 < 9
        ? '0${string(int(take(skip(currentStartDate, 5), 2)) + 1)}'
        : int(take(skip(currentStartDate, 5), 2)) + 1 > 12 ? '01' : string(int(take(skip(currentStartDate, 5), 2)) + 1)
  year: int(take(skip(currentStartDate, 5), 2)) < 12
    ? string(take(currentStartDate, 4))
    : string(int(take(currentStartDate, 4)) + 1)
}
func newStartDate(currentStartDate string) string =>
  '${calculateStartDate(currentStartDate).year}-${calculateStartDate(currentStartDate).month}-${calculateStartDate(currentStartDate).day} 00:00'

output maintenanceStartTime string = maintenanceStartDate == ''
  ? newStartDate(currentStartDate)
  : '${maintenanceStartDate} 00:00'