Payment terms configuration in OBB8

Hi guys,

Please provide me solution on below mention requirement:

due date = invoice date + 140 days + Month end + 7days.

eg: if the invoice date is 01.23, plus 140 days is 06.12, the end of 06.12 is 06.30, then plus 7days. so the due date for 01.23 is 07.07.

So basically all the due date will end up on the 7th of the month. just the months will be different.

Thanks in advance.