Allow to refer user related info using thread global `Current` (like CurrentAttributes in Rails 5.2 ;-)

current.rb

class Current

  class Default
    def self.user; nil end
    def self.admin?; false end
    def self.country
      @country ||= Rails.configuration.x.default.user_country
    end
    def self.currency
      @currency ||= Rails.configuration.x.default.user_currency
    end
    def self.timezone
      @timezone ||= Time.zone_default
    end
  end

  def self.default; Default end

  include RequestStoreDefiner
  request_store_accessor :user, :country, :currency, :admin?, :timezone

  def self.for(user)
    if user.present?
      self.user = user
      self.admin = user.admin?
      self.currency = user.currency || default.currency
      self.country = user.country || default.country
      self.timezone = user.timezone.present? ? Time.find_zone!(user.timezone) : default.timezone
    end
    self
  end

  def self.now
    self.timezone.now
  end
end

Gemfile

gem 'request_store'

request_store_definer.rb

module RequestStoreDefiner
  extend ActiveSupport::Concern
  class_methods do
    def request_store_reader(*methods)
      methods = [methods].flatten
      methods.each do |method|
        if method.to_s.last == '?'
          m = method.to_s.chop.to_sym
        else
          m = method
        end
        define_singleton_method method do
          RequestStore.store[m] || default.send(method)
        end
      end
    end
    def request_store_writer(*methods)
      methods = [methods].flatten
      methods.each do |method|
        if method.to_s.last == '?'
          m = method.to_s.chop.to_sym
          define_singleton_method "#{m}=" do |value|
            RequestStore.store[m] = value ? true : false
          end
        else
          define_singleton_method "#{method}=" do |value|
            RequestStore.store[method] = value
          end
        end
      end
    end
    def request_store_accessor(*methods)
      request_store_reader(*methods)
      request_store_writer(*methods)
    end
  end
end