require 'berkeley_library/av/constants'
require 'berkeley_library/av/metadata/fields'
require 'berkeley_library/av/metadata/source'
require 'berkeley_library/av/restrictions'

module BerkeleyLibrary
  module AV
    class Metadata
      include AV::Constants

      attr_reader :record_id, :source

      # TODO: can we stop passing in record ID / stop lazy-loading MARC?
      def initialize(record_id:, source:, marc_record: nil)
        @record_id = record_id
        @source = source
        @marc_record = marc_record
      end

      def bib_number
        return @bib_number if instance_variable_defined?(:@bib_number)

        @bib_number = source.find_bib_number(self)
      end

      def tind_id
        id_001 if source == Source::TIND
      end

      def alma_id
        id_001 if source == Source::ALMA
      end

      def marc_record
        @marc_record ||= source.record_for(record_id)
      end

      def values_by_field
        @values_by_field ||= Fields.default_values_from(marc_record).tap { |values| ensure_catalog_link(values) }
      end

      def each_value(&)
        values_by_field.each_value(&)
      end

      def title
        @title ||= (title_value = values_by_field[Fields::TITLE]) ? title_value.entries.first : UNKNOWN_TITLE
      end

      def description
        @description ||= (desc_value = values_by_field[Fields::DESCRIPTION]) ? desc_value.as_string : ''
      end

      def calnet_or_ip?
        restrictions.calnet_or_ip?
      end

      def calnet_only?
        restrictions.calnet_only?
      end

      def display_uri
        @display_uri ||= source.display_uri_for(self)
      end

      class << self
        def for_record(record_id:)
          source = Source.for_record_id(record_id)
          raise AV::RecordNotFound, "Unable to determine metadata source for record ID: #{record_id.inspect}" unless source

          Metadata.new(record_id:, source:)
        end
      end

      private

      def restrictions
        @restrictions ||= Restrictions.new(marc_record)
      end

      def id_001
        return @id_001 if instance_variable_defined?(:@id_001)
        return (@id_001 = nil) unless (cf_001 = marc_record['001'])

        @id_001 = RecordId.ensure_record_id(cf_001.value)
      end

      def ensure_catalog_link(values_by_field)
        catalog_value = values_by_field[Fields::CATALOG_LINK]
        return if catalog_value && catalog_value.includes_link?(source.catalog_link_text)

        catalog_link = Link.new(url: display_uri.to_s, body: source.catalog_link_text)

        if catalog_value
          catalog_value.entries << catalog_link
        else
          values_by_field[Fields::CATALOG_LINK] = Value.link_value(Fields::CATALOG_LINK, catalog_link)
        end
      end

    end
  end
end