USING: kernel math prettyprint combinators arrays io sequences unicode.case ;
IN: friends

: get-friend ( n arr -- n arr more )
  "Enter the name of a friend, or XXX to stop: " write

  readln dup

    "XXX" =
    [ drop
      f ]
    [ -rot [ set-nth ] 2keep
      [ 1 + ] dip
      t ]
  if ;

: get-friends ( n arr -- n arr )
  t [ ] [ get-friend ] while ;

: prompt ( n arr -- n arr )
  "[C]ount, [P]rint, or [A]dd friends? " write

  readln >lower
    { { "p" [ 2dup swap head [ print ] each ] }
      { "c" [ [ dup . ] dip                 ] }
      { "a" [ get-friends prompt            ] }
      [ drop
        "Please enter one of C, P, or A." print
        prompt ] }
  case ;

: main ( -- )
  0 30 null <array> get-friends prompt 2drop ;

MAIN: main