Refactoring example [01]

region_const.rb

# === BEFORE REFACTORING
### При добавлении нового региона необходимо также внести информацию о поддомене в файл роутов
module RegionConst

  # Местный локатив или второй предложный
  LOCATIVE = {"Москва" => "Москве", "Кемерово" => "Кемерово"}
  ACCUSATIVE = {"Москва" => "Москвы", "Кемерово" => "Кемерова"}

  SUBDOMAINS = Hash[Subdomain.all(:conditions => ['title in (?)', ['Красноярск', 'Омск', 'Новосибирск', 'Абакан', 'Барнаул', 'Москва', 'Кемерово', 'Иркутск', 'Томск', 'Россия', 'Кызыл', 'В мире', 'Чита']]).map{|r| [r.title, r]}]

  KRSK    = SUBDOMAINS['Красноярск']
  OMSK    = SUBDOMAINS['Омск']
  NSK     = SUBDOMAINS['Новосибирск']
  ABAKAN  = SUBDOMAINS['Абакан']
  BARNAUL = SUBDOMAINS['Барнаул']
  MOSCOW  = SUBDOMAINS['Москва']
  KEM     = SUBDOMAINS['Кемерово']
  IRKUTSK = SUBDOMAINS['Иркутск']
  TOMSK   = SUBDOMAINS['Томск']
  RUSSIA  = SUBDOMAINS['Россия']
  KYZYL   = SUBDOMAINS['Кызыл']
  WORLD   = SUBDOMAINS['В мире']
  CHITA = SUBDOMAINS['Чита']

  REGIONS_WITH_TV_NEWS = [KRSK, IRKUTSK, NSK, TOMSK, KEM, OMSK]

  class << self
    def all_region
      @@regions ||= [MOSCOW, KRSK, OMSK, NSK, ABAKAN, BARNAUL, KEM, IRKUTSK, TOMSK, KYZYL, CHITA]
    end

    def all_regions_for_menu
      @@regions_for_menu ||= [RUSSIA, ABAKAN, BARNAUL, IRKUTSK, KEM, KRSK, NSK, OMSK, TOMSK, KYZYL]
    end

    def subdomains
      @@subdomains ||= {
          'krsk' => KRSK,
          'omsk' => OMSK,
          'nsk'  => NSK,
          'abakan' => ABAKAN,
          'barnaul' => BARNAUL,
          'fed' => RUSSIA,
          'kem' => KEM,
          'irkutsk'=> IRKUTSK,
          'tomsk' => TOMSK,
          'kyzyl' => KYZYL,
          'chita' => CHITA
      }
    end

    def regions_for_select
      all_region.map{|x| [x.title, x.id]}
    end

    def get_locative(region)
      if region.is_a? Region or region.is_a? Subdomain
        LOCATIVE[region.title] || region.title+'е'
      else
        LOCATIVE[region] || region.to_s+'е'
      end
    end

    def get_accusative(region)
      if region.is_a? Region or region.is_a? Subdomain
        ACCUSATIVE[region.title] || region.title+'а'
      else
        ACCUSATIVE[region] || region.to_s+'а'
      end
    end
  end
end

# === AFTER REFACTORING
class RegionConst

  # allowed for processing region :marks
  ACTIVE_REGIONS = [:krsk, :omsk, :nsk, :abakan, :barnaul, :moscow, :kem, :irkutsk, :tomsk, :russia, :kyzyl, :world]

  REGIONS_WITH_TV_NEWS = [:krsk, :irkutsk, :nsk, :tomsk, :kem, :omsk]

  class << self

    # get all active regions
    def all_regions
      @@regions ||= get_regions(ACTIVE_REGIONS)
    end

    # get regions with TV news
    def regions_with_tv_news
      @@tv_news_regions ||= get_regions(REGIONS_WITH_TV_NEWS)
    end

    # consider that we trying to get only Active_regions, allow string or symbol
    def subdomain(name)
      unless name.is_a?(String) || name.is_a?(Symbol)
        raise TypeError, 'Subdomain name must be type of String of Symbol'
      end
      const_get(name.to_s.upcase)
    end

    # ===
    private

    def const_missing(name)
      set_region_const(name) || super
    end

    def get_regions(marks)
      if marks.is_a? Array
        Region.where(mark: marks)
      else
        Region.find_by_mark(marks)
      end
    end

    def set_region_const(name)
      region = get_regions(name.downcase.to_sym)
      if region
        const_set( name.to_s.upcase , region )
      end
    end

  end
end