before_singleton_action.rb

# frozen_string_literal: true

# @see https://gist.github.com/ryanlecompte/1283413
module BeforeSingletonAction
  extend ActiveSupport::Concern

  class_methods do
    def singleton_method_added(method_name)
      return if before_singleton_actions.include?(method_name) || before_singleton_action_methods.include?(method_name)

      add_before_singleton_action_to(method_name)
    end

    def before_singleton_action(method_name)
      before_singleton_actions << method_name
    end

    def before_singleton_actions
      @before_singleton_actions ||= []
    end

    def before_singleton_action_methods
      @before_singleton_action_methods ||= []
    end

    def add_before_singleton_action_to(method_name)
      before_singleton_action_methods << method_name
      original_method = method(method_name)

      define_singleton_method(method_name) do |*args, &block|
        before_singleton_actions.each do |before_singleton_action|
          method(before_singleton_action).call
        end

        original_method.call(*args, &block)
      end
    end
  end
end