module Pageable
  module ActiveRecord
    module Base
      extend ActiveSupport::Concern

      module ClassMethods

        def inherited(subclass)
          subclass.class_eval do
            if superclass == ::ActiveRecord::Base
              scope :page, ->(number) {
                limit(default_per_page).offset(default_per_page * ([number.to_i, 1].max - 1))
              } do
                include Pageable::ActiveRecord::Relation
              end
            end
          end
          super
        end

        def default_per_page(value=nil)
          unless value.nil?
            value = [value.to_i, 1].max
            @default_per_page = value
          end
          defined?(@default_per_page).nil? ? Rails.application.config.pagination.default_per_page : @default_per_page 
        end

      end
    end
  end
end