module Auth::Concerns::OwnerConcern

	extend ActiveSupport::Concern
	include Auth::Concerns::ChiefModelConcern
	included do 

		## applicability of the model which implements this concern.	
		## every model has to be explicitly set as applicable.
		## it is NOT APPLICABLE BY DEFAULT.
		field :applicable, type: Boolean, default: false


		## doc_version
		## you can use it to do find_and_update
		field :doc_version, type: Integer, default: 0


		

		## but if a resource id is present, then a resource class must be provided.

		field :resource_id, type: String
		field :resource_class, type: String

		## THERE ARE BASICALLY THREE KINDS OF USERS THAT WE MAY NEED.

		## ONE : The resource that is considered as the owner of the object . this uses the resource_id and resource_class. It is got by calling get_resource on the object.

		attr_accessor :owner_resource

		## SIGNED_IN_RESOURCE : the resource that is currently signed in, and should be assigned to this model instance, in the controller. In the controller this can be got by calling the method currently_signed_in_resource, provided that the controller implements the token_concern.

		attr_accessor :signed_in_resource


		validates_presence_of :resource_class, if: Proc.new{|c| !c.resource_id.nil?}

		## you cannot change the resource_id or owner of the object once it is set.
		validate :resource_id_not_changed	


		

	end

	module ClassMethods

		## used in cart_item_controller_concern#show
		## if the resource is nil, will look for a cart item, which has a resource of nil, otherwise will look for a cart item, with the provided resource id.
		## 
		def find_self(_id,resource,options={})
			conditions = {:_id => _id}
			conditions[:resource_id] = resource.id.to_s if !resource.is_admin?
			#puts "conditions are:"
			#puts conditions.to_s
			all = self.where(conditions)
			#puts "the resultant size:"
			#puts all.size.to_s
			return all.first if all.size > 0 
			return nil
		end

	end

	## returns the resource that was associated with the object when the object was created.
	## it basically uses the resource_id and resource_class that were saved, when creating the resource.
	## since resources can be created without the resource_class and resource_id being provided, it may return nil if these two are not present.
	def get_resource
		return unless (self.resource_class && self.resource_id) 
		unless owner_resource
			
			owner_resource = self.resource_class.capitalize.constantize.find(self.resource_id)
		end
		owner_resource
	end

	## checks if the owner of the current object is the same as the owner of the other object passed in.
	## this is currently used in payment_concern, in a before_save validation def.
	## this is also used in the cart_item_concern, as a before_update validation , if the parent_id is changing, where we check if the cart_item owner is the same as that of the cart.
	def owner_matches(other_object)
		return false unless other_object.respond_to? :resource_id
		return false if self.resource_id != other_object.resource_id
	end

	def is_applicable?
		## what if this is embedded.
		self.applicable
	
	end

	


	private

	def resource_id_not_changed
	  ##this method will give you access to be able to reset the resource_id in case the admin is modifying the resource.
	  ##need to check if that can be done?
	  if resource_id_changed? && resource_id_was
	      errors.add(:resource_id, "You cannot change the ownership of this entity")
	  end
	end

end