module Beaker
  module Shared
    module Semvar

      #Is semver-ish version a less than semver-ish version b
      #@param [String] a A version of the from '\d.\d.\d.*'
      #@param [String] b A version of the form '\d.\d.\d.*'
      #@return [Boolean] true if a is less than b, otherwise return false
      #
      #@note 3.0.0-160-gac44cfb is greater than 3.0.0, and 2.8.2
      #@note -rc being less than final builds is not yet implemented.
      def version_is_less a, b
        a_nums = a.split('-')[0].split('.')
        b_nums = b.split('-')[0].split('.')
        (0...a_nums.length).each do |i|
          if i < b_nums.length
            if a_nums[i].to_i < b_nums[i].to_i
              return true
            elsif a_nums[i].to_i > b_nums[i].to_i
              return false
            end
          else
            return false
          end
        end
        #checks all dots, they are equal so examine the rest
        a_rest = a.split('-', 2)[1]
        b_rest = b.split('-', 2)[1]
        if a_rest and b_rest and a_rest < b_rest
          return false
        elsif a_rest and not b_rest
          return false
        elsif not a_rest and b_rest
          return true
        end
        return false
      end

      # Gets the max semver version from a list of them
      # @param [Array<String>]  versions  List of versions to get max from
      # @param [String]         default   Default version if list is nil or empty
      #
      # @note nil values will be skipped
      # @note versions parameter will be copied so that the original
      #   won't be tampered with
      #
      # @return [String, nil] the max string out of the versions list or the
      #   default value if the list is faulty, which can either be set or nil
      def max_version(versions, default=nil)
        return default if !versions || versions.empty?
        versions_copy = versions.dup
        highest = versions_copy.shift
        versions_copy.each do |version|
          next if !version
          highest = version if version_is_less(highest, version)
        end
        highest
      end
    end
  end
end