^(.+)\s+-\s+(.+?)\s+[fF](t|eat(uring)?)?\.?([^([\])\n]+)(.+)?$

// Formats an audio filename that has the "...featuring artist" part at the end of filename.
//------------------------------------------------------------------------------------------
 
 
// Pseudo-Example:
//
// From: [0]ARTIST_NAME  [1]DASH  [2]TRACK_TITLE  [3]FEAT_ARTIST  [4]POSSIBLE_ADDITIONAL_INFO_INSIDE:()[]{}
// To:   [0]ARTIST_NAME  [3]FEAT_ARTIST  [1]DASH  [2]TRACK_TITLE  [4]POSSIBLE_ADDITIONAL_INFO_INSIDE:()[]{}
 
// Real-Example:
//
// From: Carbin & Sirmark - Sorry Feat. Sevener.mp3
// To:   Carbin & Sirmark Feat. Sevener - Sorry.mp3
 
// Known limitations:
//
// • If [0]ARTIST_NAME or [2]TRACK_TITLE parts contains any " - " the script will not work properlly.
//   By default the script prevents any replacement on that kind of filenames, so don't worry.
 
 
var
  rgxPattern: string;
  rgxReplace: string;
  dashCount: integer;
  baseName: string;
  extension: WideString;
 
begin
 
  baseName  := WideExtractBaseName(FileName)
  extension := WideExtractFileExt(FileName);
 
  // The regular expression that matches the filename parts.
  // http://stackoverflow.com/questions/32807698/regex-pattern-to-limit-dashes-in-these-circumstances
  rgxPattern := '^(.+)\s+-\s+(.+?)\s+[fF](t|eat(uring)?)?\.?([^([\])\n]+)(.+)?$'
  rgxReplace := '$1 Feat.$5 - $2$6'
 
  // The amount of " - " that contains the filename.
  dashCount := high(MatchesRegEx(baseName, '\s-\s' , false));
 
  // If only one " - " is found then...
  If (dashCount = 0) Then
    begin // Do the replacement.
      baseName := ReplaceRegEx(baseName, rgxPattern, rgxReplace, false, true)
      FileName := baseName + extension;
    end;
 
end.