module Customize
	module Inherited
		def self.included base
			base.extend ClassMethods
			base.has_one :inherit_node, :class_name=>Customize::InheritNode.name, :as=>:node, :dependent=>:destroy

			base.after_create { |object|
				object.create_inherit_node :left=>0, :right=>1
			}

			base.before_destroy { |object|
				raise 'object should not have children when destroy' if object.inherit_node.children.size > 0
			}
			
		end

		module ClassMethods
		end

		def inherit parent
			raise 'should be save first' if self.new_record?
			raise 'should be same class' if self.class != parent.class
			inherit_node.parent_id = parent.inherit_node.id
			right = parent.inherit_node.right
			InheritNode.where("right >= ?", inherit_node.left).update_all("right = right+2")
			inherit_node.left = right
			inherit_node.right = right + 1
			inherit_node.save
		end

		def ascent_ids
			@ascent_ids ||=
				InheritNode.where("left < :left and right > :right and node_type = :type",
													:left=>inherit_node.left, :right=>inherit_node.right, :type=>self.class.name).pluck(:node_id)
		end

		def descent_ids
			r = InheritNode.where("left > :left and right < :right and node_type = :type",
												:left=>inherit_node.left, :right=>inherit_node.right, :type=>self.class.name)
			r.pluck(:node_id)
		end

		def ascents
			self.class.find ascent_ids
		end

	end
end