class Step
  has_and_belongs_to_many :pre_steps, foreign_key: :pre, class_name: 'Step', inverse_of: :post_steps
  has_and_belongs_to_many :post_steps, foreign_key: :post, class_name: 'Step', inverse_of: :pre_steps
end

require 'mongoid/relations/metadata'

class Mongoid::Relations::Metadata
  def determine_inverse_foreign_key
    if has_key?(:inverse_of)
      if inverse_class_name? && inverse_of
        inverse_class_name.constantize.relations[inverse_of.to_s].foreign_key
      else
        inverse_of ? "#{inverse_of.to_s.singularize}#{relation.foreign_key_suffix}" : nil
      end
    else
      "#{inverse_class_name.demodulize.underscore}#{relation.foreign_key_suffix}"
    end
  end
end