translations.rake

namespace :translations do
  desc "Show available locales"
  task :available => :environment do
    puts "Available locales: #{I18n.available_locales.join(', ')}"
  end

  desc "Show missed translations depending on default language environment (:#{I18n.default_locale} by default). You can change it providing LOCALE argument"
  task :missed => :environment do
    locale = ENV['LOCALE'] || I18n.default_locale
    puts "Using :#{locale} as default locale"
    
    i18n_backend = I18n.backend
    i18n_backend.send(:init_translations) unless i18n_backend.initialized?
    translations = i18n_backend.send(:translations)

    main_translation = translations.delete(locale.to_sym)
    
    translations.each do |key, value|
      print "Checking :#{key} translations:"
      diff = find_keys_diff(main_translation, value)
      if diff.empty?
        puts " is up to date"
      else
        puts " here is list of missed translation keys"
        puts "\t" + merge_diff(diff).sort.join("\n\t")
      end
    end
  end

  private
  def find_keys_diff(master, in_hash)
    master.inject([]) do |result, value|
      key = value.first
      if !in_hash.has_key?(key)
        result << key.to_s
      elsif value.last.is_a?(Hash)
        diff = find_keys_diff(master[key], in_hash[key])
        result << { key.to_s => diff } unless diff.empty?
      end
      result
    end
  end

  def merge_diff(diff, prefix = "")
    prefix << "." unless prefix.blank?
    diff.inject([]) do |result, value|
      if value.is_a?(Hash)
        result += merge_diff(value.first.last, prefix + value.first.first)
      else
        result << "#{prefix}#{value}"
      end
      result
    end
  end
end