Version checksum report

digest_check.rb

# Checks the shasum of each version and current content in old production
# and compares it to those in new production.
#
# To run the report, go to the Rails console and copy-in the two classes in the file.
# Then run:
# 
#   > report = ChecksumReport.new
# 
# The report is an array of hashes, each of which looks like:
#
#   { id: "1234", valid: true }
#
class FileChecksum
  attr_reader :file

  # @param [GenericFile] gf object from Fedora
  def initialize(gf)
    @file = gf
  end

  # @return [String] sha1sum of the current content, i.e. what is at /content in Fedora
  def current
    return unless file.content.present?
    file.content.digest.first.to_s
  end

  # @return [Hash] sha1sums of each of the file's versions
  def versions
    return {} unless file.content.present?
    file.content.versions.all.each do |v|
      version_hash[v.label] = shasum_for_version(v)
    end
    version_hash
  end

  # @return [Boolean] when the current checksum is present in the list of version checksums
  def valid?
    versions.values.include?(current)
  end

  private

    def digest_predicate
      ::RDF::URI("http://fedora.info/definitions/v4/repository#digest")
    end

    def graph_from_response(response)
      ::RDF::Graph.new << ::RDF::Reader.for(:ttl).new(response.body)
    end

    def version_hash
      @version_hash ||= {}
    end

    def shasum_for_version(version)
      metadata_uri = version.uri + "/fcr:metadata"
      graph = graph_from_response(ActiveFedora.fedora.connection.get(metadata_uri))
      graph.query(predicate: digest_predicate).first.object.to_s
    end

end

class ChecksumReport
  attr_reader :results

  def initialize(ids = [])
    @results = []
    file_ids = ids.present? ? ids : all_ids
    file_ids.each do |id|
      gf = GenericFile.find(id)
      checksum = FileChecksum.new(gf)
      @results << { id: id, valid: checksum.valid? }
    end
  end

  private

    def all_ids
      ActiveFedora::SolrService.query("active_fedora_model_ssi:GenericFile", fl: [:id], rows: 10_000).map do |hit|
        hit.fetch("id")
      end
    end
end