require 'marc/spec/queries/selector'

module MARC
  module Spec
    module Queries
      class IndicatorValue
        include Selector

        # ------------------------------------------------------------
        # Constants

        VALID_INDICATORS = [1, 2].freeze

        # ------------------------------------------------------------
        # Attributes

        attr_reader :tag, :ind

        # ------------------------------------------------------------
        # Initializer

        def initialize(ind)
          @ind = valid_indicator(ind)
        end

        # ------------------------------------------------------------
        # Object overrides

        def to_s
          "^#{ind}"
        end

        # ------------------------------
        # Applicable

        def can_apply?(marc_obj)
          %i[indicator1 indicator2].all? { |m| marc_obj.respond_to?(m) }
        end

        # ------------------------------------------------------------
        # Protected methods

        protected

        # ------------------------------
        # Applicable

        def do_apply(marc_obj)
          ind_val = ind_val_for(marc_obj)
          ind_val ? [ind_val] : []
        end

        def equality_attrs
          %i[ind]
        end

        private

        def ind_val_for(data_field)
          case ind
          when 1
            data_field.indicator1
          when 2
            data_field.indicator2
          end
        end

        def valid_indicator(ind_val)
          ind = int_or_nil(ind_val)
          return ind if VALID_INDICATORS.include?(ind)

          raise ArgumentError, "Not a valid indicator: #{ind_val.inspect}"
        end
      end
    end
  end
end