module Volt
  module Persistors
    # StoreState provides method for a store to track its loading state.
    module StoreState
      # Called when a collection loads
      def loaded(initial_state = nil)
        change_state_to(initial_state || :not_loaded)
      end

      def state
        @state_dep ||= Dependency.new
        @state_dep.depend
        @state
      end

      # Called from the QueryListener when the data is loaded
      def change_state_to(new_state, skip_trigger = false)
        old_state = @state
        @state    = new_state

        # Trigger changed on the 'state' method
        unless skip_trigger
          if old_state != @state
            @state_dep.changed! if @state_dep
          end
        end

        if @state == :loaded && @fetch_promises
          # Trigger each waiting fetch
          @fetch_promises.compact.each { |fp| fp.resolve(@model) }
          @fetch_promises = nil

          stop_listening
        end
      end
    end
  end
end