brew/Library/Homebrew/cask/lib/hbc/container/base.rb

module Hbc
  class Container
    class Base
      def initialize(cask, path, command, nested: false)
        @cask = cask
        @path = path
        @command = command
        @nested = nested
      end

      def extract_nested_inside(dir)
        children = Pathname.new(dir).children

        nested_container = children[0]

        unless children.count == 1 &&
               !nested_container.directory? &&
               @cask.artifacts[:nested_container].empty? &&
               extract_nested_container(nested_container)

          children.each do |src|
            dest = @cask.staged_path.join(src.basename)
            FileUtils.rm_r(dest) if dest.exist?
            FileUtils.mv(src, dest)
          end
        end
      end

      def extract_nested_container(source)
        container = Container.for_path(source, @command)

        return false unless container

        ohai "Extracting nested container #{source.basename}"
        container.new(@cask, source, @command, nested: true).extract

        true
      end
    end
  end
end