Is there documentation for `/search` endpoint middlewares?

Hi there,
there are bunch of middlewares that are used in /search endpoint. For our purposes we want to modify them a bit, but we realized that it's quite difficult to understand what actually these middlewares are used for and how they all are working with each other.

Do you have documentation for this logic?

Something like:

1. sanitize parameters (convert comma-separated values to arrays, validate country code, etc.)
2. validate language parameter if exists (use https://github.com/florrain/locale library)
3. validate size parameter if exists
4. libpostal middleware
    execute 
       if there are no errors in request
       if source parameter is not "whosonfirst"
    perform "parse_text" function and return hash with categorized query terms, for example:
    "ettlinger strasse 10" => { street: "ettlinger strasse", "number": 10 }
5. ...