submit-social-housing-lettings-and-sales-data/app/services/storage/archive_service.rb

module Storage
  class ArchiveService < StorageService
    MAX_SIZE = 50 * (1024**2) # 50MiB

    def initialize(archive_io)
      super()
      @archive = Zip::File.open_buffer(archive_io)
    end

    def list_files(folder)
      @archive.glob(File.join(folder, "*.*"))
              .map(&:name)
    end

    def folder_present?(folder)
      !list_files(folder).empty?
    end

    def get_file_io(file_name)
      entry = @archive.get_entry(file_name)
      raise "File too large to be extracted" if entry.size > MAX_SIZE

      entry.get_input_stream
    end
  end
end