# A mixin to the GDor::Indexer::SolrDocBuilder class.
# Methods for Solr field values determined from the DOR object's purl page public xml
module GDor::Indexer::PublicXmlFields
  # value is used to tell SearchWorks UI app of specific display needs for objects
  # a config file value for add_display_type can be used to prepend a string to
  #  xxx_collection or xxx_object
  # e.g., Hydrus objects are a special display case
  # Based on a value of :add_display_type in a collection's config yml file
  #
  # information on DOR content types:
  #   https://consul.stanford.edu/display/chimera/DOR+content+types%2C+resource+types+and+interpretive+metadata
  # @return String the string to pre-pend to the display_type value  (e.g. )
  # @return [String] 'collection' or DOR content type
  def display_type
    case dor_content_type
    when 'book'
      'book'
    when 'image', 'manuscript', 'map'
      'image'
    else
      'file'
    end
  end

  # the @id attribute of resource/file elements that match the display_type, including extension
  # @return [Array<String>] filenames
  def file_ids
    @file_ids ||= begin
      ids = []
      if content_md
        if display_type == 'image'
          content_md.root.xpath('resource[@type="image"]/file/@id').each do |node|
            ids << node.text unless node.text.empty?
          end
        elsif display_type == 'file'
          content_md.root.xpath('resource/file/@id').each do |node|
            ids << node.text unless node.text.empty?
          end
        end
      end
      return nil if ids.empty?
      ids
    end
  end

  # @return true if the identityMetadata has <objectType>collection</objectType>, false otherwise
  def collection?
    resource.collection?
  end

  def collections
    resource.collections
  end

  protected #---------------------------------------------------------------------

  # the value of the type attribute for a DOR object's contentMetadata
  #  more info about these values is here:
  #    https://consul.stanford.edu/display/chimera/DOR+content+types%2C+resource+types+and+interpretive+metadata
  #    https://consul.stanford.edu/display/chimera/Summary+of+Content+Types%2C+Resource+Types+and+their+behaviors
  # @return [String]
  def dor_content_type
    @dor_content_type ||= begin
      dct = content_md ? content_md.root.xpath('@type').text : nil
      logger.error "#{druid} has no DOR content type (<contentMetadata> element may be missing type attribute)" if !dct || dct.empty?
      dct
    end
  end

  # the contentMetadata for this object, derived from the public_xml
  # @return [Nokogiri::XML::Element] containing the contentMetadata
  def content_md
    resource.content_metadata
  end

  # the identityMetadata for this object, derived from the public_xml
  # @return [Nokogiri::XML::Element] containing the identityMetadata
  def identity_md
    resource.identity_metadata
  end
end # GDor::Indexer::SolrDocBuilder class