module ActiveStorage::Blob::Identifiable

def download_identifiable_chunk
  if byte_size.positive?
    service.download_chunk key, 0...4.kilobytes
  else
    ""
  end
end

def identified?
  identified
end

def identify
  identify_without_saving
  save!
end

def identify_content_type
  Marcel::MimeType.for download_identifiable_chunk, name: filename.to_s, declared_type: content_type
end

def identify_without_saving
  unless identified?
    self.content_type = identify_content_type
    self.identified = true
  end
end