def validate_and_setup_metadata_of_submission
    case File.extname(file_cache.to_s)
      when '.zip'
        validate_and_setup_metadata_of_submission_for_zip_file
      when '.tex'
        validate_and_setup_metadata_of_submission_for_tex_file
      else
        return
    end
  end
  # rubocop:enable all

  def validate_and_setup_metadata_of_submission_for_zip_file
    begin
      Zip::File.open("./public/uploads/tmp/#{file_cache}") do |zip_file|
        if zip_file.glob('*.tex').size != 1
          errors.add(:many_tex_files, 'The zip-file contain less or more than the one tex-file.')
          break
        end
        tex_file = zip_file.glob('*.tex').first
        stream_from_tex_file_utf8 = tex_file.get_input_stream.read.force_encoding('utf-8')
        metadata_from_tex_file = MetadataExtractor.new(stream_from_tex_file_utf8)
        if metadata_from_tex_file.data_about_article.empty? || metadata_from_tex_file.authors.empty?
          errors.add(:no_metadata, 'The tex-file does not the metadata.')
          break
        end

        setup_metadata_of_sumbmission(metadata_from_tex_file)
      end
    rescue Zip::Error
      errors.add(:incorrect_zip_file, 'The zip-file is not correct')
    end
  end

  def validate_and_setup_metadata_of_submission_for_tex_file
    metadata_from_tex_file = MetadataExtractor.new(self.file.read.force_encoding('utf-8'))
    if metadata_from_tex_file.data_about_article.empty? || metadata_from_tex_file.authors.empty?
      errors.add(:no_metadata, 'The tex-file does not the metadata.')
    end
    setup_metadata_of_sumbmission(metadata_from_tex_file)
  end

  def setup_metadata_of_sumbmission(metadata_from_tex_file)
    self.name = metadata_from_tex_file.data_about_article[:title]
    authors.destroy_all
    metadata_from_tex_file.authors.each_with_index do |author|
      authors.new(name: author[:author].to_s)
    end
  end