Delete songs present in the itunes music folder but not in itunes library

itunes_cleaner.rb

#!/usr/bin/env ruby
#
# Dependencies:
#
# This script requires to build and install the branch 'location' of this https://github.com/jaymcgavren/itunes-library fork of 'itunes-library'
# It also requires to install 'colorize' gem
#
# License: GPLv2
# http://www.gnu.org/licenses/gpl-2.0.html
#

require 'rubygems'
require 'itunes-library/library'
require 'find'
require 'colorize'

ITUNES_DIR='/Users/therobot/Music/iTunes/iTunes Music'
ITUNES_LIBRARY='/Users/therobot/Music/iTunes/iTunes Music Library.xml'
MEGABYTE = 1024.0 * 1024.0

def to_mb bytes
  bytes /  MEGABYTE
end

def get_itunes_library
  library = ITunes::Library.load(ITUNES_LIBRARY)
  begin
    library.size
  rescue
    puts "iTunes library not found, check the ITUNES_LIBRARY constant for a valid path to the itunes music library xml."
    exit -1
  end
  library
end

def find_and_clean(library)
  total_size = 0
  Find.find(ITUNES_DIR) do |f|
    unless File.directory?(f)
      total_size += clean_file(f, library)
    end
  end
  puts "A total of #{(to_mb(total_size)).to_s} MB have been freed."
end

def song_in_itunes?(file, library)
  library.music.tracks.select { |t| t.location.sub('file://localhost','').downcase == file.downcase }.empty?
end

def podcast_in_itunes?(file, library)
  library.podcasts.tracks.select { |t| t.location.sub('file://localhost','').downcase == file.downcase }.empty?
end

def file_in_itunes?(file, library)
  ! song_in_itunes?(file, library) || ! podcast_in_itunes?(file, library)
end

def is_dsstore?(file)
  File.basename(file) == '.DS_Store'
end

def mark_for_deletion(file, library)
  mark = true
  if is_dsstore?(file)
    puts "Deleting file #{file.red}"
  elsif ! file_in_itunes?(file, library)
    puts "Deleting #{file.red} since it is not your in itunes anymore but the file still exists."
  else
    mark = false
  end
  mark
end

def clean_file(file, library)
  size = 0
  if mark_for_deletion(file, library)
    size = File.size(file)
    File.delete(file)
  end
  size
end

def main
  library = get_itunes_library
  find_and_clean(library)
end

main