nextDayOfTheWeek function
Return a new instance DateTime with next day of the week
from
DateTime that will have incremented days
weekday
use 1 for Sunday .. 7 for Saturday
Implementation
DateTime nextDayOfTheWeek(DateTime from, int weekday) {
assert(weekday <= 7, 'weekday:$weekday must be less or equal then 7');
assert(weekday > 0, 'weekday:$weekday must be grater then 0');
var myWeekDay = (from.weekday == 7 ? 0 : from.weekday);
return from.add(
Duration(days: myWeekDay == weekday ? 7 : (myWeekDay - weekday).abs()));
}