Calculate weekday end date based on sum of weekday start date and cell value

It seems like this shouldn't be that hard, but for some reason I'm stumped.

I have a cell that has a weekday start date. I have another cell that has a number in it for the duration of work days. I need a formula that will add the duration of work days to the start date, and return a weekday completion date. The part I'm hung up on is making sure that the completion date is a weekday.

If the start date is a Monday, and the duration is one day, the completion date would be Monday. If the start date is a Monday, and the duration is 2 days, the completion date would be Tuesday. If the start date is a Thursday, and the duration is 3 days, the completion date would be the following Monday. I hope you can see the pattern.

Here is the formula I have so far; it's close, but it doesn't seem to span weekends quite right and I'm not sure what/ how it needs to change.

Cell A1 = Start Date (a weekday)
Cell A2 = Number of days (duration)
Cell A3 = End Date (a weekday)

A3 = IF((A1=""),"",IF((A2=""),"TBD",(A2+A1)+CHOOSE(WEEKDAY((A2+A1)),1,1,1,1,1,3,2)))

If there is a better solution please propose it!
Thanks in advance!

Try using WORKDAY function, i.e.

= IF(A1="","",IF(A2="","TBD",WORKDAY(A1-1,A2)))