Quickly sort related files in a given directory into subdirectories

file_sort.rb

#! /usr/bin/env ruby
##
# Quickly sort related files in a given directory into
#   subdirectories of that same directory
#
# defaults to the current working directory if no supplied path

require 'fileutils'

base_dir = ARGV[0] || Dir.pwd

Dir.chdir base_dir do
  # all non-directory files, then sort them
  files = Dir.glob('*').reject { |f| File.directory?(f) }
  files.map(&:downcase).sort!

  files.each do |file|
    # determine the delimiter (better if it found most-frequent-matched character)
    # build a pattern to match filenames against (Should only contain the first 
    #   characters and words of each file name)
    # bail if the pattern is too short
    delimiter = file[/[\W_]/]
    parts = []
    file.split(delimiter).each do |part|
      break if part[/^\D{2,}/].nil? && (!parts.empty? && part.length > 1)
      parts << part
    end
    pattern = parts.join(delimiter).gsub(/\./, '\.').downcase
    next unless pattern.length > 4

    # match all files against the previously-built patter
    # if a pattern matches more than one file, create a
    # directory for that pattern and move all matching
    # files into said directory
    # delete any matched file names from the files array
    matches = files.select { |f| f[/#{pattern}/i] }
    if matches.count > 1
      relname = pattern.split(delimiter).map(&:capitalize).join(delimiter).gsub(/\\\./, '.')
      dirname = File.join(base_dir, relname)
      unless Dir.exists?(dirname)
        puts "=> Creating Directory:  #{dirname}"
        Dir.mkdir(dirname)
      end

      matches.each do |fname|
        old_file = File.join(base_dir, fname)
        new_file = File.join(dirname, fname)
        puts "-> Moving  #{fname}"
        FileUtils.mv(old_file, new_file)
        files.delete(fname)
      end 
    end
  end
end