Web application interacting with an Excel spreadsheet formulas and VBA

I'd like to build a web application that can interact with an Excel file created by my colleagues.

Basically users should be able to set a few parameters via a web form then click on a submit button, then the formulas and macros in the Excel file would be computed/run with these parameters and we would display the results on the web page.

Why:

The idea is that we don't want users to have access to the actual Excel file because we don't want them to have access to the code, so putting it on a web app seemed like a good idea because they can only input some parameters and see the outputs of the computations.

Discarded solutions:

I looked into Aspose and Spreadsheet Gear but apparently neither can run VBA.

I found companies (EASA, Sumwise) that turn your Excel file into a web app but no idea how they do it.

I also read about Microsoft Interop but it's apparently not the best idea to use it on the server side (http://ift.tt/1GP8cWa)

Would anyone have any idea if this is possible somehow? Thanks in advance!