Using I4GL to determine payperiods.... new report processor?

Hello Group..... I've come across another interesting problem (aren't they all....), and I'm petitioning for some help. Here goes..... We have a pay / commission setup which doesn't really do any "time-traveling" for accounting. IE, someone pays, late in the commission period, we run commissions, the sales person gets a check, and then the next day the payment bounces. Oops. Problem being, if the client pays again, the sales person gets credited again. Which means, lost $$$'s because they got paid twice for a single client. To solve this problem, I need to be able to figure out previous payments, and their dates (done), and then check back-in-time to see if during any payperiod (for which they have payments) the client was fully paid. Seems simple enough, although it's a few queries, if the report is taking 2 minutes instead of 1, that's fine. How do I find the payperiods. Depending on the type of client, the payperiod could be Type 1: (1st - 15th, 16th - end of month) OR Type 2: (1st - end of month). Once I've fetched the date from the db, say 09/12/2003 and determined that it's Type 1, how do I say "ah, yes, this falls in Type 1"? [I think I have that solved, with a simple <= or >= ... anything easier?] BUT, if it falls after the 16th, or is Type 2, what could I use (in I4GL) to find the last date in the month (short of a text file or table w/ payperiods)? Lastly .... I would like to eventually move away from 4GL as a report processor, in liu of something a bit more "modern". Something similar to JasperReports would be ideal (can you do functions in JasperReports?), but commercial would be ok as well. Any ideas? Thanks. --Anthony