Create C# app that can calculate my trading P&L

I have a trade blotter that contains 5 columns of data: Date, Time, Buy/Sell, Symbol, Execution Price. Sometimes I open & close positions in the same day (flat), sometimes I don't (carry overnight). From my trade blotter I want to be able to see columns in a DataGrid (or whatever control you think is best) for : 1) The P&L in the stock after a closing trade is made (might still have an open position) 2) The P&L in the stock after position is ENTIRELY CLOSED / FLAT (i.e. 0 shares) 3) A summary of P&L in each stock per day I once wrote code that did this years ago (in VB) so I'm fairly knowledgeable about the work involved. If you have questions I would be able to help you get into the code.