country_checker.rb

class CountryChecker
  COUNTRY_DB = nil # FIX

  def initialize(app, options = {})
    @app = app
    @ip_override = options[:allow_ip_override]
  end

  def call(env)
    request = Rack::Request.new(env)
    ip = @ip_override ? request.params['ip'] : request.ip
    country = COUNTRY_DB.country(ip).country

    if valid_domain?(country)
      redirect_to_domain(country)
    else
      @app.call(env)
    end
  end