Bibtex: Full first name, just middle name initial

Question

I've been trying to create a "custom" bibliography style with the full first name and only middle name initials. I copied plain.bst and tried modifying the format.names function, by changing ff~ to ff. and a few other options but it didn't work. I'm using the info from https://tex.stackexchange.com/a/36677/160651.

I assume I need to change more parts of the function, to check for the first and or second words in the first names, but I really can't understand how to do this...

Here's the format.names function for easy reference (from plain.bst)

FUNCTION {format.names}
{ 's :=
  #1 'nameptr :=
  s num.names$ 'numnames :=
  numnames 'namesleft :=
    { namesleft #0 > }
    { s nameptr "{f~}{vv~}{ll}{, jj}" format.name$ 't :=
      nameptr #1 >
        { namesleft #1 >
            { ", " * t * }
            { numnames #2 >
                { "," * }
                'skip$
              if$
              t "others" =
                { " et~al." * }
                { " and " * t * }
              if$
            }
          if$
        }
        't
      if$
      nameptr #1 + 'nameptr :=
      namesleft #1 - 'namesleft :=
    }
  while$
}