module NinjaModel
  module Associations
    class SingularAssociation < Association
      def reader(force_reload = false)
        if force_reload
          klass.uncached { reload }
        elsif !loaded? || stale_target?
          reload
        end

        target
      end

      def writer(record)
        replace(record)
      end

      def create(attributes = {}, options = {}, &block)
        create_record(attributes, options, &block)
      end

      def create!(attributes = {}, options = {}, &block)
        create_record(attributes, options, true, &block)
      end

      def build(attributes = {}, options = {})
        record = build_record(attributes, options)
        yield(record) if block_given?
        set_new_record(record)
        record
      end

      private

      def create_scope
        scoped.scope_for_create.stringify_keys.except(klass.primary_key)
      end

      def find_target
        scoped.first.tap { |record| set_inverse_instance(record) }
      end

      def replace(record)
        raise NotImplementedError, "Subclasses must implement a replace(record) method"
      end

      def set_new_record(record)
        replace(record)
      end

      def create_record(attributes, options, raise_error = false)
        record = build_record(attributes, options)
        yield(record) if block_given?
        saved = record.save
        set_new_record(record)
        raise RecordInvalid.new(record) if !saved && raise_error
        record
      end
    end
  end
end