module ActiveData
  module Model
    module Associations
      class EmbedsOne < EmbedsAny
        attr_reader :destroyed

        def build(attributes = {})
          self.target = build_object(attributes)
        end

        def create(attributes = {})
          build(attributes).tap(&:save)
        end

        def create!(attributes = {})
          build(attributes).tap(&:save!)
        end

        def apply_changes
          if target
            if target.destroyed? || target.marked_for_destruction?
              @destroyed = target
              clear
            else
              target.save
            end
          else
            true
          end
        end

        def target=(object)
          if object
            callback(:before_add, object)
            setup_performers! object
          end
          loaded!
          @target = object
          callback(:after_add, object) if object
        end

        def load_target
          source = read_source
          source ? reflection.klass.instantiate(source) : default
        end

        def default
          return if evar_loaded?

          default = reflection.default(owner)

          return unless default

          object = if default.is_a?(reflection.klass)
            default
          else
            reflection.klass.with_sanitize(false) do
              build_object(default)
            end
          end
          object.send(:clear_changes_information) if reflection.klass.dirty?
          object
        end

        def clear
          target.try(:destroy)
          reload.nil?
        end

        def reader(force_reload = false)
          reload if force_reload
          target
        end

        def replace(object)
          if object
            raise AssociationTypeMismatch.new(reflection.klass, object.class) unless object.is_a?(reflection.klass)
            transaction do
              clear
              self.target = object
              apply_changes! if owner.persisted?
            end
          else
            clear
          end

          target
        end
        alias_method :writer, :replace

      private

        def setup_performers!(object)
          embed_object(object)
          association = self

          object.define_save do
            association.send(:write_source, attributes)
          end

          object.define_destroy do
            association.send(:write_source, nil)
            true
          end
        end
      end
    end
  end
end