Move SolrDocument to decorator pattern

app/models/concerns/iiif_print/solr_document_decorator.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+module IiifPrint
+  module SolrDocumentDecorator
+    def digest_sha1
+      digest[/urn:sha1:([\w]+)/, 1]
+    end
+
+    def method_missing(method_name, *args, &block)
+      super unless iiif_print_solr_field_names.include? method_name.to_s
+      self[IiifPrint.solr_name(method_name.to_s)]
+    end
+
+    def respond_to_missing?(method_name, include_private = false)
+      iiif_print_solr_field_names.include?(method_name.to_s) || super
+    end
+
+    # @see https://github.com/samvera/hyrax/commit/7108409c619cd2ba4ae8c836b9f3b429a7e9837b
+    def file_set_ids
+      # Yes, this looks a little odd.  But the truth is the prior key (e.g. `file_set_ids_ssim`) was
+      # an alias of `member_ids_ssim`.
+      self['member_ids_ssim']
+    end
+
+    def any_highlighting?
+      response&.[]('highlighting')&.[](id)&.present?
+    end
+
+    def solr_document
+      self
+    end
+  end
+end
+
+SolrDocument.prepend(IiifPrint::SolrDocumentDecorator)
+SolrDocument.attribute :is_child, Hyrax::SolrDocument::Metadata::Solr::String, 'is_child_bsi'
+SolrDocument.attribute :split_from_pdf_id, Hyrax::SolrDocument::Metadata::Solr::String, 'split_from_pdf_id_ssi'
+SolrDocument.attribute :digest, Hyrax::SolrDocument::Metadata::Solr::String, 'digest_ssim'
+
+# @note These properties came from the newspaper_works gem.  They are configurable.
+SolrDocument.class_attribute :iiif_print_solr_field_names, default: %w[alternative_title genre
+                                                                       issn lccn oclcnum held_by text_direction
+                                                                       page_number section author photographer
+                                                                       volume issue_number geographic_coverage
+                                                                       extent publication_date height width
+                                                                       edition_number edition_name frequency preceded_by
+                                                                       succeeded_by]

lib/iiif_print/engine.rb

@@ -63,10 +63,6 @@ class Engine < ::Rails::Engine
         end
       end
     end
-
-    config.after_initialize do
-      IiifPrint::Solr::Document.decorate(SolrDocument)
-    end
     # rubocop:enable Metrics/BlockLength
   end
 end

spec/models/solr_document_spec.rb

@@ -11,4 +11,26 @@
       expect(solr_doc.file_set_ids).to eq(['bar'])
     end
   end
+
+  describe 'iiif_print decorator' do
+    it 'has extra attributes' do
+      expect(solr_doc).to respond_to(:is_child)
+      expect(solr_doc).to respond_to(:split_from_pdf_id)
+      expect(solr_doc).to respond_to(:digest)
+    end
+
+    it 'has extra class attributes' do
+      expect(described_class.iiif_print_solr_field_names).to eq %w[alternative_title genre
+                                                                   issn lccn oclcnum held_by text_direction
+                                                                   page_number section author photographer
+                                                                   volume issue_number geographic_coverage
+                                                                   extent publication_date height width
+                                                                   edition_number edition_name frequency preceded_by
+                                                                   succeeded_by]
+    end
+
+    it 'has a method that returns itself' do
+      expect(solr_doc.solr_document).to be solr_doc
+    end
+  end
 end