Library for building dependencies with ActiveResource

gistfile1.rb

module ResourceHas
  def self.included base
    unless base.ancestors.include? InheritedResources::Base
      raise '%s must inherit from InheritedResources::Base to implement ResourceHas' % base.name
    end
    base.extend(ClassMethods)
    base.append_before_filter :__build_relations
  end
  ## Class methods
  module ClassMethods
    def __get_resources
      @resources ||= {}
    end
    def resource_has(*args, &block)
      raise 'at least 2 arguments expected for resource_has (amount and relation name)' if args.length < 2
      modifier = args.shift() unless args[0].is_a? Integer
      amount = args.shift()
      relation_name = args.shift()
      self.__get_resources[relation_name] = {
        :modifier => modifier,
        :amount => amount,
        :block => block,
        :options => { :increment_by => amount, :on => %w(edit) }.merge(args.shift || {})
      }
    end
  end
  ## Instance methods
  protected

  def __build_relations
    self.class.__get_resources.each_pair do |relation_name, args|
      return unless (args[:options][:only] || args[:options][:on]).include?(action_name)
      __quantify(relation_name, args).times do
        nested_resource = resource_method_chain __get_builder_method(relation_name)
        args[:block].call(nested_resource) if args[:block]
      end
    end
  end

  def __quantify(relation_name, args)
    return args[:options][:increment_by] unless args[:modifier]
    quantifier = args[:amount] - resource.send(relation_name).try(:length).to_i
    if args[:modifier].to_sym === :at_least
      return args[:options][:increment_by] if quantifier < args[:options][:increment_by]
      quantifier
    elsif args[:modifier].to_sym === :at_most
      return args[:options][:increment_by] if (quantifier + args[:options][:increment_by]) < args[:amount]
      quantifier
    end
  end

  def __get_builder_method(relation_name)
    return 'build_%s' % relation_name if __get_single_relations.include?(resource.class.reflect_on_association(relation_name).macro)
    return '%s.build' % relation_name
  end

  def resource_method_chain(method_chain)
    return resource if method_chain.empty?
    method_chain.split('.').flatten.inject(self.resource){ |object, method| object.send(method.to_sym) }
  end

  def __get_single_relations
    [:has_one]
  end
end

resource_has 3, :images, :increment_by => 3, :only => %w(edit)
resource_has :at_least, 3, :images, :increment_by => 1, :only => %w(edit)
resource_has :at_most, 3, :images, :increment_by => 3, :only => %w(edit)