module Spotlight::Resources
  # Base Resource indexer for objects in DOR
  class DorResource < Spotlight::Resource
    include ActiveSupport::Benchmarkable

    ##
    # Generate solr documents for the DOR resources identified by this object
    #
    # @return [Enumerator] an enumerator of solr document hashes for indexing
    def to_solr
      return to_enum(:to_solr) { size } unless block_given?

      benchmark "Indexing resource #{inspect} (est. #{size} items)" do
        base_doc = super

        indexable_resources.each_with_index do |res, idx|
          benchmark "Indexing item #{res.druid} in resource #{id} (#{idx} / #{size})" do
            doc = to_solr_document(res)
            yield base_doc.merge(doc) if doc
          end
        end
      end
    end

    def resource
      @resource ||= Spotlight::Dor::Resources.indexer.resource doc_id
    end

    private

    ##
    # Enumerate the resource, and any collection members, that should be indexed
    # into this exhibit
    #
    # @return [Enumerator] an enumerator of resources to index
    def indexable_resources
      return to_enum(:indexable_resources) { 1 + resource.items.size } unless block_given?

      yield resource

      resource.items.each do |r|
        yield r
      end
    end

    ##
    # Estimate the number of documents this resource will create
    def size
      indexable_resources.size
    end

    ##
    # Generate the solr document hash for a given resource by applying the current
    # indexer steps.
    #
    # @return [Hash]
    def to_solr_document(resource)
      Spotlight::Dor::Resources.indexer.solr_document(resource)
    rescue RuntimeError => e
      logger.error("Error processing #{resource.druid}: #{e}")
      nil
    end

    ##
    # Write any logs (or benchmarking information) from this class to the gdor logs
    def logger
      Spotlight::Dor::Resources.indexer.logger
    end
  end
end