class InterviewFilesCollectionService
  def initialize(files, folder_name)
    @files = files
    @folder_name = folder_name
  end

  def build
    Dir.mktmpdir { |dir|
      files.each do |file|
        open("#{dir}/#{file.filename}", 'wb') do |tmp_file|
          tmp_file << open(file.service_url.to_s).read
        end
      end

      read_files = Dir.entries("#{dir}/").select { |f| !File.directory? f }
      raise StandardError.new "Files not found." unless read_files.any?
      yield(dir, read_files)
    }
  end

  private

  attr_reader :files, :folder_name
end