module CloudBackup

  class DriverStack

    attr_accessor :max_items

    def initialize
      @list = []
      @max_items = 2
      @file_names = []
    end

    def list
      @list
    end

    def addable? driver
      driver.is_a? CloudBackup::Driver
    end

    def add_driver konstant
      @list << konstant
    end

    def add_file name
      @file_names << name
    end

    def add_files array
      @file_names = @file_names + array
    end

    def perform_backup!
      driver_initiate
      driver_add_files
      driver_upload_files
      driver_remove_old_files
      driver_shut_down_execution
    end

    def driver_initiate
      @list.each do |driver|
        driver.initiate
      end
    end

    protected

    def driver_add_files
      @list.each do |driver|
        @file_names.each do |file_name|
          driver.add_file file_name
        end
      end
    end

    def driver_upload_files
      @list.each do |driver|
        driver.upload
      end
    end

    def driver_remove_old_files
      @list.each do |driver|
        names = driver.list_by_date
        (names - names.first(@max_items)).each do |name|
          driver.remove name
        end
      end
    end

    def driver_shut_down_execution
      @list.each do |driver|
        driver.terminate
      end
    end

  end

end