ファイルパスから MP3 に適切な ID3 Tag を設定する

Gemfile

source 'http://rubygems.org'

gem 'mercenary'
gem 'taglib-ruby'

updid3.rb

#!/usr/bin/env ruby
require 'bundler/setup'
require 'mercenary'
require 'taglib'

def fix (basedir, options = { })
  Dir.glob(File.join(basedir, '**/*.mp3')).each do |path|
    regexp = Regexp.new('^(\d+)(:?\s|-)+')
    attrs  = { }

    %i{ title album artist }.inject(path) do |memo, key|
      value = File.basename(memo, '.mp3')

      if key == :title && match = regexp.match(value)
        attrs[:track] = match[0].to_i
        value.gsub!(regexp, '')
      end

      attrs[key] = value

      File.dirname(memo)
    end

    puts "Artist: #{attrs[:artist]}"
    puts " Album: #{attrs[:album]}"
    puts " Title: #{attrs[:title]}"
    puts " Track: #{attrs[:track]}"
    puts '--------------------------------------------------------------------------------'

    next if options[:dryrun]

    TagLib::MPEG::File.open(path) do |mp3|
      tag = mp3.tag
      attrs.each { |key, value| tag.send(:"#{key}=", value) }
      mp3.save
    end
  end
end


Mercenary.program :updid3 do |program|
  program.version     '0.0.1'
  program.description 'Update ID3 tag from file path'
  program.syntax      "#{$0} directory [directory ...]"
  program.option      :dryrun, '-n', '--dry-run', 'Perform a trial run with no changes made'

  program.action do |directories, options|
    if directories.empty?
      puts program
    else
      directories.each { |directory| fix(directory, options) }
    end
  end
end