module DelegateIfNil

# File lib/delegate_if_nil.rb, line 8
def nil_delegate(*attrs, to:)
  attrs.each do |attr|
    define_method attr do
      self[attr].nil? ? send(to)&.send(attr) : self[attr]
    end

    source_method = "#{attr}_source".to_sym
    define_method source_method do
      return "self" unless self[attr].nil?

      if send(to)&.respond_to?(source_method)
        to_source = send(to).send(source_method)
        return to.to_s if to_source == "self"

        return to_source
      else
        return send(to)&.send(attr).nil? ? "unset" : to.to_s
      end
    end

    delegted_bool_method = "#{attr}_delegated?".to_sym
    define_method delegted_bool_method do
      self[attr].nil?
    end
  end
end