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I'm currently learning C#, implementing a project with Visual Studio Community. I want it clean and appropriately organized from the start, so, as a general rule, I try not to mix the UI code with the underlying logic; also, I'd like specific parts the code to be used across the whole project.

Hence I made a class populationIdParserWorker in a separate file than the respective UI element, PopulationIdParser. It worked just fine, until I came up with an idea to add a progress bar to the UI. I learned that to make it actually show the progress, I can use BackgroundWorker to introduce the necessary multi-threading. I've been doing some research on how to use it, but I only found such examples, where the actual logic was done inside the UI code, which doesn't seem appropriate to me in terms of bigger projects. So I came up with the idea to pass my worker_DoWork method's arguments to the actual logic, located in populationIdParserWorker class' method process_file_lite. Is it a good practice or should it be done another way? How else can I do it?

Side note: The thing isn't working quite the way it is supposed to, because the progress bar is reaching some point and then the UI holds for a moment, only for the bar to jump to the end immediately. I'm not sure if it has something to do with my method of passing the arguments as a reference - I'm going to check it soon. I'm not convinced yet, because the bar freezes just after all true work has been done, i.e. the remaining lines of the file are meaningless, so they are being read and skipped.

Here are the pieces of code:

From PopulationIdParser.xaml.cs: