Refactor main method and increase test coverage

[jmrt47]

Is your feature request related to a problem?

The main method of the evergreen action piled up over time and is mostly untested.

Describe the solution you'd like

The idea is to refactor the method by chopping it into chunks with clear purpose and additional description. With each chunk separated from the main method also tests should be introduced to improve quality of evergreen.

Describe alternatives you've considered

No response

Additional context

No response