# customize behavior for IiifSearch
module NewspaperWorks
  module BlacklightIiifSearch
    module AnnotationBehavior
      ##
      # Create a URL for the annotation
      # use a Hyrax-y URL syntax:
      # protocol://host:port/concern/model_type/work_id/manifest/canvas/file_set_id/annotation/index
      # @return [String]
      def annotation_id
        "#{base_url}/manifest/canvas/#{file_set_id}/annotation/#{hl_index}"
      end

      ##
      # Create a URL for the canvas that the annotation refers to
      # match the Hyrax default canvas URL syntax:
      # protocol://host:port/concern/model_type/work_id/manifest/canvas/file_set_id
      # @return [String]
      def canvas_uri_for_annotation
        "#{base_url}/manifest/canvas/#{file_set_id}#{coordinates}"
      end

      private

        ##
        # return a string like "#xywh=100,100,250,20"
        # corresponding to coordinates of query term on image
        # @return [String]
        def coordinates
          return default_coords if query.blank?
          coords_json = fetch_and_parse_coords
          return default_coords unless coords_json && coords_json['coords']
          query_terms = query.split(' ').map(&:downcase)
          matches = coords_json['coords'].select do |k, _v|
            k.downcase =~ /(#{query_terms.join('|')})/
          end
          return default_coords if matches.blank?
          coords_array = matches.values.flatten(1)[hl_index]
          return default unless coords_array
          "#xywh=#{coords_array.join(',')}"
        end

        ##
        # return the JSON word-coordinates file contents
        # @return [JSON]
        def fetch_and_parse_coords
          coords = NewspaperWorks::Data::WorkDerivatives.new(file_set_id).data('json')
          return nil if coords.blank?
          begin
            JSON.parse(coords)
          rescue JSON::ParserError
            nil
          end
        end

        ##
        # a default set of coordinates
        # @return [String]
        def default_coords
          '#xywh=0,0,0,0'
        end

        ##
        # the base URL for the Newspaper object
        # use polymorphic_url, since we deal with multiple object types
        # @return [String]
        def base_url
          host = controller.request.base_url
          controller.polymorphic_url(parent_document, host: host, locale: nil)
        end

        ##
        # return the first file set id
        # @return [String]
        def file_set_id
          file_set_ids = document['file_set_ids_ssim']
          raise "#{self.class}: NO FILE SET ID" if file_set_ids.blank?
          file_set_ids.first
        end
    end
  end
end