module Net
  module SFTP
    # A class for describing the current version of a library. The version
    # consists of three parts: the +major+ number, the +minor+ number, and the
    # +tiny+ (or +patch+) number.
    #
    # Two Version instances may be compared, so that you can test that a version
    # of a library is what you require:
    #
    #   require 'net/sftp/version'
    #
    #   if Net::SFTP::Version::CURRENT < Net::SFTP::Version[2,1,0]
    #     abort "your software is too old!"
    #   end
    class Version
      include Comparable

      # A convenience method for instantiating a new Version instance with the
      # given +major+, +minor+, and +tiny+ components.
      def self.[](major, minor, tiny, pre = nil)
        new(major, minor, tiny, pre)
      end

      attr_reader :major, :minor, :tiny

      # Create a new Version object with the given components.
      def initialize(major, minor, tiny, pre = nil)
        @major, @minor, @tiny, @pre = major, minor, tiny, pre
      end

      # Compare this version to the given +version+ object.
      def <=>(version)
        to_i <=> version.to_i
      end

      # Converts this version object to a string, where each of the three
      # version components are joined by the '.' character. E.g., 2.0.0.
      def to_s
        @to_s ||= [@major, @minor, @tiny, @pre].compact.join(".")
      end

      # Converts this version to a canonical integer that may be compared
      # against other version objects.
      def to_i
        @to_i ||= @major * 1_000_000 + @minor * 1_000 + @tiny
      end

      # The major component of this version of the Net::SFTP library
      MAJOR = 4

      # The minor component of this version of the Net::SFTP library
      MINOR = 0

      # The tiny component of this version of the Net::SFTP library
      TINY  = 2

      # The prerelease component of this version of the Net::SFTP library
      # nil allowed
      PRE   = "backports"

      # The current version of the Net::SFTP library as a Version instance
      CURRENT = new(*[MAJOR, MINOR, TINY, PRE].compact)

      # The current version of the Net::SFTP library as a String
      STRING = CURRENT.to_s
    end
  end
end