class Exporter < BaseService
  def call
    export!
  end

  private

  def export!
    s3.upload_stream_zip do |zip|
      zip.write_deflated_file(filename) do |sink|
        find_in_batches do |batch|
          batch.each do |line|
            sink << CSV.generate_line(line)
          end
        end
      end
    end
  end

  def find_in_batches
    loop do
      batch = fetch_lines(offset)

      yield(offset, batch)

      break if batch.length < BATCH_SIZE

      offset += BATCH_SIZE
    end
  end
end