Batch rename mp3 files

id3_renamer.rb

#!/usr/bin/env ruby

require "rubygems"
require "id3lib"

File.instance_eval do
  def mp3?(path)
    File.extname(path).downcase == '.mp3'
  end
end

class Mp3Renamer
  class << self
    def rename_file(file)
      begin
        name = format_name(file)
        puts "Renaming #{File.basename(file)} to #{name}..."
        File.rename(file, File.dirname(file) + "/" + name)
      rescue
        puts
        puts "Error renaming #{File.basename(file)}"
        puts
      end
    end
    
    def rename_directory(dir)
      dir_scan(dir) do |file|
        next unless File.mp3? file
        
        rename_file file
      end
    end
    
    private
    
    def dir_scan(directory, &block)
      Dir.foreach(directory) do |file|
        next if [".", ".."].include? file
        
        path = directory + "/" + file
        
        if File.directory? path
          dir_scan path, &block
        else
          yield path if block_given?
        end
      end
    end
    
    def format_name(file)
      tag = ID3Lib::Tag.new(file, ID3Lib::V1)
      
      "#{tag.track.rjust(2, '0')} - #{tag.artist} - #{tag.title}.mp3"
    end
  end
end

base_path = $*[0] || "."

if $*.include? '--install'
  require 'win32/registry.rb'
  
  puts "Installing shell extension..."
  
  shell = Win32::Registry::HKEY_CLASSES_ROOT.open("Directory\\shell")
  
  unless shell.keys.include? 'id3_renamer'
    shell.create('id3_renamer') do |reg|
      reg.write('', Win32::Registry::REG_SZ, "Rename files by ID3")
      reg.create("command") do |command|
        command.write("", Win32::Registry::REG_SZ, "\"C:\\ruby\\bin\\ruby.exe\" \"#{File.expand_path __FILE__}\" \"%1\"")
      end
    end
  end
else
  Mp3Renamer.rename_directory(base_path)
end