# encoding:utf-8
#--
# Copyright (C) 2005-2014 Bob Aman
#
#    Licensed under the Apache License, Version 2.0 (the "License");
#    you may not use this file except in compliance with the License.
#    You may obtain a copy of the License at
#
#        http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS,
#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#    See the License for the specific language governing permissions and
#    limitations under the License.
#++


$:.unshift(File.dirname(__FILE__))

require 'uri'
require 'time'
require 'thread'
require 'digest/sha1'
require 'digest/md5'

require 'uuidtools/version'

begin
  require 'securerandom'
rescue LoadError
  require File.join(File.dirname(__FILE__), 'compat', 'securerandom')
end

module UUIDTools
  ##
  # UUIDTools was designed to be a simple library for generating any
  # of the various types of UUIDs.  It conforms to RFC 4122 whenever
  # possible.
  #
  # @example
  #   UUID.md5_create(UUID_DNS_NAMESPACE, "www.widgets.com")
  #   # => #<UUID:0x287576 UUID:3d813cbb-47fb-32ba-91df-831e1593ac29>
  #   UUID.sha1_create(UUID_DNS_NAMESPACE, "www.widgets.com")
  #   # => #<UUID:0x2a0116 UUID:21f7f8de-8051-5b89-8680-0195ef798b6a>
  #   UUID.timestamp_create
  #   # => #<UUID:0x2adfdc UUID:64a5189c-25b3-11da-a97b-00c04fd430c8>
  #   UUID.random_create
  #   # => #<UUID:0x19013a UUID:984265dc-4200-4f02-ae70-fe4f48964159>
  class UUID
    include Comparable

    ##
    # @api private
    @@last_timestamp = nil

    ##
    # @api private
    @@last_node_id = nil

    ##
    # @api private
    @@last_clock_sequence = nil

    ##
    # @api private
    @@state_file = nil

    ##
    # @api private
    @@mutex = Mutex.new

    ##
    # Creates a new UUID structure from its component values.
    # @see UUID.md5_create
    # @see UUID.sha1_create
    # @see UUID.timestamp_create
    # @see UUID.random_create
    # @api private
    def initialize(time_low, time_mid, time_hi_and_version,
        clock_seq_hi_and_reserved, clock_seq_low, nodes)
      unless time_low >= 0 && time_low < 4294967296
        raise ArgumentError,
          "Expected unsigned 32-bit number for time_low, got #{time_low}."
      end
      unless time_mid >= 0 && time_mid < 65536
        raise ArgumentError,
          "Expected unsigned 16-bit number for time_mid, got #{time_mid}."
      end
      unless time_hi_and_version >= 0 && time_hi_and_version < 65536
        raise ArgumentError,
          "Expected unsigned 16-bit number for time_hi_and_version, " +
          "got #{time_hi_and_version}."
      end
      unless clock_seq_hi_and_reserved >= 0 && clock_seq_hi_and_reserved < 256
        raise ArgumentError,
          "Expected unsigned 8-bit number for clock_seq_hi_and_reserved, " +
          "got #{clock_seq_hi_and_reserved}."
      end
      unless clock_seq_low >= 0 && clock_seq_low < 256
        raise ArgumentError,
          "Expected unsigned 8-bit number for clock_seq_low, " +
          "got #{clock_seq_low}."
      end
      unless nodes.kind_of?(Enumerable)
        raise TypeError,
          "Expected Enumerable, got #{nodes.class.name}."
      end
      unless nodes.size == 6
        raise ArgumentError,
          "Expected nodes to have size of 6."
      end
      for node in nodes
        unless node >= 0 && node < 256
          raise ArgumentError,
            "Expected unsigned 8-bit number for each node, " +
            "got #{node}."
        end
      end
      @time_low = time_low
      @time_mid = time_mid
      @time_hi_and_version = time_hi_and_version
      @clock_seq_hi_and_reserved = clock_seq_hi_and_reserved
      @clock_seq_low = clock_seq_low
      @nodes = nodes
    end

    ##
    # Returns the value of attribute `time_low`
    attr_accessor :time_low

    ##
    # Returns the value of attribute `time_mid`
    attr_accessor :time_mid

    ##
    # Returns the value of attribute `time_hi_and_version`
    attr_accessor :time_hi_and_version

    ##
    # Returns the value of attribute `clock_seq_hi_and_reserved`
    attr_accessor :clock_seq_hi_and_reserved

    ##
    # Returns the value of attribute `clock_seq_low`
    attr_accessor :clock_seq_low

    ##
    # Returns the value of attribute `nodes`
    attr_accessor :nodes

    ##
    # Parses a UUID from a string.
    def self.parse(uuid_string)
      unless uuid_string.kind_of? String
        raise TypeError,
          "Expected String, got #{uuid_string.class.name} instead."
      end
      uuid_components = uuid_string.downcase.scan(UUIDTools::UUID_REGEXP).first
      raise ArgumentError, "Invalid UUID format." if uuid_components.nil?
      time_low = uuid_components[0].to_i(16)
      time_mid = uuid_components[1].to_i(16)
      time_hi_and_version = uuid_components[2].to_i(16)
      clock_seq_hi_and_reserved = uuid_components[3].to_i(16)
      clock_seq_low = uuid_components[4].to_i(16)
      nodes = []
      6.times do |i|
        nodes << uuid_components[5][(i * 2)..(i * 2) + 1].to_i(16)
      end
      return self.new(time_low, time_mid, time_hi_and_version,
        clock_seq_hi_and_reserved, clock_seq_low, nodes)
    end

    ##
    # Parses a UUID from a raw byte string.
    def self.parse_raw(raw_string)
      unless raw_string.kind_of? String
        raise TypeError,
          "Expected String, got #{raw_string.class.name} instead."
      end

      if raw_string.respond_to?(:force_encoding)
        raw_string.force_encoding(Encoding::ASCII_8BIT)
      end

      raw_length = raw_string.length
      if raw_length < 16
        # Option A: Enforce raw_string be 16 characters (More strict)
        #raise ArgumentError,
        #  "Expected 16 bytes, got #{raw_string.length} instead."

        # Option B: Pad raw_string to 16 characters (Compatible with existing behavior)
        raw_string = raw_string.rjust(16, "\0")
      elsif raw_length > 16
        # NOTE: As per "Option B" above, existing behavior would use the lower
        # 128-bits of an overly long raw_string instead of using the upper 128-bits.
        start_index = raw_length - 16
        raw_string = raw_string[start_index...raw_length]
      end

      raw_bytes = []
      if raw_string[0].respond_to? :ord
        for i in 0...raw_string.size
          raw_bytes << raw_string[i].ord
        end
      else
        raw_bytes = raw_string
      end

      time_low = ((raw_bytes[0] << 24) +
                  (raw_bytes[1] << 16)  +
                  (raw_bytes[2] << 8)  +
                   raw_bytes[3])
      time_mid = ((raw_bytes[4] << 8) +
                   raw_bytes[5])
      time_hi_and_version = ((raw_bytes[6] << 8) +
                              raw_bytes[7])
      clock_seq_hi_and_reserved = raw_bytes[8]
      clock_seq_low = raw_bytes[9]
      nodes = []
      for i in 10...16
        nodes << raw_bytes[i]
      end

      return self.new(time_low, time_mid, time_hi_and_version,
                      clock_seq_hi_and_reserved, clock_seq_low, nodes)
    end

    ##
    # Parses a UUID from an Integer.
    def self.parse_int(uuid_int)
      unless uuid_int.kind_of?(Integer)
        raise ArgumentError,
          "Expected Integer, got #{uuid_int.class.name} instead."
      end

      time_low = (uuid_int >> 96) & 0xFFFFFFFF
      time_mid = (uuid_int >> 80) & 0xFFFF
      time_hi_and_version = (uuid_int >> 64) & 0xFFFF
      clock_seq_hi_and_reserved = (uuid_int >> 56) & 0xFF
      clock_seq_low = (uuid_int >> 48) & 0xFF
      nodes = []
      for i in 0..5
        nodes << ((uuid_int >> (40 - (i * 8))) & 0xFF)
      end

      return self.new(time_low, time_mid, time_hi_and_version,
                      clock_seq_hi_and_reserved, clock_seq_low, nodes)
    end

    ##
    # Parse a UUID from a hexdigest String.
    def self.parse_hexdigest(uuid_hex)
      unless uuid_hex.kind_of?(String)
        raise ArgumentError,
          "Expected String, got #{uuid_hex.class.name} instead."
      end

      time_low = uuid_hex[0...8].to_i(16)
      time_mid = uuid_hex[8...12].to_i(16)
      time_hi_and_version = uuid_hex[12...16].to_i(16)
      clock_seq_hi_and_reserved = uuid_hex[16...18].to_i(16)
      clock_seq_low = uuid_hex[18...20].to_i(16)
      nodes_string = uuid_hex[20...32]
      nodes = []
      for i in 0..5
        nodes << nodes_string[(i * 2)..(i * 2) + 1].to_i(16)
      end

      return self.new(time_low, time_mid, time_hi_and_version,
                      clock_seq_hi_and_reserved, clock_seq_low, nodes)
    end

    ##
    # Creates a UUID from a random value.
    def self.random_create()
      new_uuid = self.parse_raw(SecureRandom.random_bytes(16))
      new_uuid.time_hi_and_version &= 0x0FFF
      new_uuid.time_hi_and_version |= (4 << 12)
      new_uuid.clock_seq_hi_and_reserved &= 0x3F
      new_uuid.clock_seq_hi_and_reserved |= 0x80
      return new_uuid
    end

    ##
    # Creates a UUID from a timestamp.
    def self.timestamp_create(timestamp=nil)
      # We need a lock here to prevent two threads from ever
      # getting the same timestamp.
      @@mutex.synchronize do
        # Always use GMT to generate UUIDs.
        if timestamp.nil?
          gmt_timestamp = Time.now.gmtime
        else
          gmt_timestamp = timestamp.gmtime
        end
        # Convert to 100 nanosecond blocks
        gmt_timestamp_100_nanoseconds = (gmt_timestamp.tv_sec * 10000000) +
          (gmt_timestamp.tv_usec * 10) + 0x01B21DD213814000
        mac_address = self.mac_address
        node_id = 0
        if mac_address != nil
          nodes = mac_address.split(":").collect do |octet|
            octet.to_i(16)
          end
        else
          nodes = SecureRandom.random_bytes(6).unpack("C*")
          nodes[0] |= 0b00000001
        end
        6.times do |i|
          node_id += (nodes[i] << (40 - (i * 8)))
        end
        clock_sequence = @@last_clock_sequence
        if clock_sequence.nil?
          clock_sequence = self.convert_byte_string_to_int(
            SecureRandom.random_bytes(16)
          )
        end
        if @@last_node_id != nil && @@last_node_id != node_id
          # The node id has changed.  Change the clock id.
          clock_sequence = self.convert_byte_string_to_int(
            SecureRandom.random_bytes(16)
          )
        elsif @@last_timestamp != nil &&
            gmt_timestamp_100_nanoseconds <= @@last_timestamp
          clock_sequence = clock_sequence + 1
        end
        @@last_timestamp = gmt_timestamp_100_nanoseconds
        @@last_node_id = node_id
        @@last_clock_sequence = clock_sequence

        time_low = gmt_timestamp_100_nanoseconds & 0xFFFFFFFF
        time_mid = ((gmt_timestamp_100_nanoseconds >> 32) & 0xFFFF)
        time_hi_and_version = ((gmt_timestamp_100_nanoseconds >> 48) & 0x0FFF)
        time_hi_and_version |= (1 << 12)
        clock_seq_low = clock_sequence & 0xFF;
        clock_seq_hi_and_reserved = (clock_sequence & 0x3F00) >> 8
        clock_seq_hi_and_reserved |= 0x80

        return self.new(time_low, time_mid, time_hi_and_version,
          clock_seq_hi_and_reserved, clock_seq_low, nodes)
      end
    end

    ##
    # Creates a UUID using the MD5 hash.  (Version 3)
    def self.md5_create(namespace, name)
      return self.create_from_hash(Digest::MD5, namespace, name)
    end

    ##
    # Creates a UUID using the SHA1 hash.  (Version 5)
    def self.sha1_create(namespace, name)
      return self.create_from_hash(Digest::SHA1, namespace, name)
    end

    ##
    # This method applies only to version 1 UUIDs.
    # Checks if the node ID was generated from a random number
    # or from an IEEE 802 address (MAC address).
    # Always returns false for UUIDs that aren't version 1.
    # This should not be confused with version 4 UUIDs where
    # more than just the node id is random.
    def random_node_id?
      return false if self.version != 1
      return ((self.nodes.first & 0x01) == 1)
    end

    ##
    # Returns true if this UUID is the
    # nil UUID (00000000-0000-0000-0000-000000000000).
    def nil_uuid?
      return false if self.time_low != 0
      return false if self.time_mid != 0
      return false if self.time_hi_and_version != 0
      return false if self.clock_seq_hi_and_reserved != 0
      return false if self.clock_seq_low != 0
      self.nodes.each do |node|
        return false if node != 0
      end
      return true
    end

    ##
    # Returns the UUID version type.
    # Possible values:
    # 1 - Time-based with unique or random host identifier
    # 2 - DCE Security version (with POSIX UIDs)
    # 3 - Name-based (MD5 hash)
    # 4 - Random
    # 5 - Name-based (SHA-1 hash)
    def version
      return (time_hi_and_version >> 12)
    end

    ##
    # Returns the UUID variant.
    # Possible values:
    # 0b000 - Reserved, NCS backward compatibility.
    # 0b100 - The variant specified in this document.
    # 0b110 - Reserved, Microsoft Corporation backward compatibility.
    # 0b111 - Reserved for future definition.
    def variant
      variant_raw = (clock_seq_hi_and_reserved >> 5)
      result = nil
      if (variant_raw >> 2) == 0
        result = 0x000
      elsif (variant_raw >> 1) == 2
        result = 0x100
      else
        result = variant_raw
      end
      return (result >> 6)
    end

    ##
    # Returns true if this UUID is valid.
    def valid?
      if [0b000, 0b100, 0b110, 0b111].include?(self.variant) &&
        (1..5).include?(self.version)
        return true
      else
        return false
      end
    end

    ##
    # Returns the IEEE 802 address used to generate this UUID or
    # nil if a MAC address was not used.
    def mac_address
      return nil if self.version != 1
      return nil if self.random_node_id?
      return (self.nodes.collect do |node|
        sprintf("%2.2x", node)
      end).join(":")
    end

    ##
    # Returns the timestamp used to generate this UUID
    def timestamp
      return nil if self.version != 1
      gmt_timestamp_100_nanoseconds = 0
      gmt_timestamp_100_nanoseconds +=
        ((self.time_hi_and_version  & 0x0FFF) << 48)
      gmt_timestamp_100_nanoseconds += (self.time_mid << 32)
      gmt_timestamp_100_nanoseconds += self.time_low
      return Time.at(
        (gmt_timestamp_100_nanoseconds - 0x01B21DD213814000) / 10000000.0)
    end

    ##
    # Compares two UUIDs lexically
    def <=>(other_uuid)
      return nil unless other_uuid.is_a?(UUIDTools::UUID)
      check = self.time_low <=> other_uuid.time_low
      return check if check != 0
      check = self.time_mid <=> other_uuid.time_mid
      return check if check != 0
      check = self.time_hi_and_version <=> other_uuid.time_hi_and_version
      return check if check != 0
      check = self.clock_seq_hi_and_reserved <=>
        other_uuid.clock_seq_hi_and_reserved
      return check if check != 0
      check = self.clock_seq_low <=> other_uuid.clock_seq_low
      return check if check != 0
      6.times do |i|
        if (self.nodes[i] < other_uuid.nodes[i])
          return -1
        end
        if (self.nodes[i] > other_uuid.nodes[i])
          return 1
        end
      end
      return 0
    end

    ##
    # Returns a representation of the object's state
    def inspect
      return "#<UUID:0x#{self.object_id.to_s(16)} UUID:#{self.to_s}>"
    end

    ##
    # Returns the hex digest of the UUID object.
    def hexdigest
      (self.frozen? ?
        generate_hexdigest : (@hexdigest ||= generate_hexdigest)
      ).dup
    end

    ##
    # Returns the raw bytes that represent this UUID.
    def raw
      (self.frozen? ? generate_raw : (@raw ||= generate_raw)).dup
    end

    ##
    # Returns a string representation for this UUID.
    def to_s
      (self.frozen? ? generate_s : (@string ||= generate_s)).dup
    end
    alias_method :to_str, :to_s

    ##
    # Returns an integer representation for this UUID.
    def to_i
      self.frozen? ? generate_i : (@integer ||= generate_i)
    end

    ##
    # Returns a URI string for this UUID.
    def to_uri
      return "urn:uuid:#{self.to_s}"
    end

    ##
    # Returns an integer hash value.
    def hash
      self.frozen? ? generate_hash : (@hash ||= generate_hash)
    end

  protected
    ##
    # Generates the hex digest of the UUID object.
    #
    # @api private
    def generate_hexdigest
      return self.to_i.to_s(16).rjust(32, "0")
    end

    # Generates an integer hash value.
    #
    # @api private
    def generate_hash
      return self.to_i % 0x3fffffff
    end

    ##
    # Generates an integer representation for this UUID.
    #
    # @api private
    def generate_i
      return (begin
        bytes = (time_low << 96) + (time_mid << 80) +
          (time_hi_and_version << 64) + (clock_seq_hi_and_reserved << 56) +
          (clock_seq_low << 48)
        6.times do |i|
          bytes += (nodes[i] << (40 - (i * 8)))
        end
        bytes
      end)
    end

    ##
    # Generates a string representation for this UUID.
    #
    # @api private
    def generate_s
      result = sprintf("%8.8x-%4.4x-%4.4x-%2.2x%2.2x-", @time_low, @time_mid,
        @time_hi_and_version, @clock_seq_hi_and_reserved, @clock_seq_low);
      6.times do |i|
        result << sprintf("%2.2x", @nodes[i])
      end
      return result.downcase
    end

    ##
    # Generates the raw bytes that represent this UUID.
    #
    # @api private
    def generate_raw
      return self.class.convert_int_to_byte_string(self.to_i, 16)
    end

  public
    ##
    # Returns true if this UUID is exactly equal to the other UUID.
    def eql?(other)
      return self == other
    end

    #
    # Determine what OS we're running on.  Helps decide how to find the MAC
    #
    def self.os_class
      require 'rbconfig'
      os_platform = RbConfig::CONFIG['target_os']
      os_class = nil
      if (os_platform =~ /win/i && !(os_platform =~ /darwin/i)) ||
          os_platform =~ /w32/i
        os_class = :windows
      elsif os_platform =~ /solaris/i
        os_class = :solaris
      elsif os_platform =~ /netbsd/i
        os_class = :netbsd
      elsif os_platform =~ /openbsd/i
        os_class = :openbsd
      end
    end

    # making these class variables helps with testing
    @ifconfig_command = "ifconfig"
    @ifconfig_path_default = "/sbin/ifconfig"
    @ip_command = "ip"
    @ip_path_default = "/sbin/ip"

    class << self
      attr_accessor :ifconfig_command, :ifconfig_path_default
      attr_accessor :ip_command, :ip_path_default
    end

    #
    # Find the path of the ifconfig(8) command if it is present
    #
    def self.ifconfig_path
      path = `which #{UUID.ifconfig_command} 2>/dev/null`.strip
      path = UUID.ifconfig_path_default if (path == "" && File.exist?(UUID.ifconfig_path_default))
      return (path === "" ? nil : path)
    end

    #
    # Find the path of the ip(8) command if it is present
    #
    def self.ip_path
      path = `which #{UUID.ip_command} 2>/dev/null`.strip
      path = UUID.ip_path_default if (path == "" && File.exist?(UUID.ip_path_default))
      return (path === "" ? nil : path)
    end

    #
    # Call the ifconfig or ip command that is found
    #
    def self.ifconfig(all=nil)
      # find the path of the ifconfig command
      ifconfig_path = UUID.ifconfig_path

      # if it does not exist, try the ip command
      if ifconfig_path == nil
        ifconfig_path = "#{UUID.ip_path} addr list"
        # all makes no sense when using ip(1)
        all = nil
      end

      all_switch = all == nil ? "" : "-a"
      return `#{ifconfig_path} #{all_switch}` if not ifconfig_path == nil
    end

    # Match and return the first Mac address found
    def self.first_mac(instring)
      mac_regexps = [
        Regexp.new("address:? (#{(["[0-9a-fA-F]{2}"] * 6).join(":")})"),
        Regexp.new("addr:? (#{(["[0-9a-fA-F]{2}"] * 6).join(":")})"),
        Regexp.new("ether:? (#{(["[0-9a-fA-F]{1,2}"] * 6).join(":")})"),
        Regexp.new("HWaddr:? (#{(["[0-9a-fA-F]{2}"] * 6).join(":")})"),
        Regexp.new("link/ether? (#{(["[0-9a-fA-F]{2}"] * 6).join(":")})"),
        Regexp.new("(#{(["[0-9a-fA-F]{2}"] * 6).join(":")})"),
        Regexp.new("(#{(["[0-9a-fA-F]{2}"] * 6).join("-")})")
      ]
      parse_mac = lambda do |output|
        (mac_regexps.map do |regexp|
           result = output[regexp, 1]
           result.downcase.gsub(/-/, ":") if result != nil
        end).compact.first
      end

      mac = parse_mac.call(instring)
      if mac
        # expand octets that were compressed (solaris)
        return (mac.split(':').map do |octet|
          (octet.length == 1 ? "0#{octet}" : octet)
        end).join(':')
      else
        return nil
      end
    end

    ##
    # Returns the MAC address of the current computer's network card.
    # Returns nil if a MAC address could not be found.
    def self.mac_address
      if !defined?(@@mac_address)
        require 'rbconfig'

        os_class = UUID.os_class

        if os_class == :windows
          begin
            @@mac_address = UUID.first_mac `ipconfig /all`
          rescue
          end
        else # linux, bsd, macos, solaris
          @@mac_address = UUID.first_mac(UUID.ifconfig(:all))
        end

        if @@mac_address != nil
          if @@mac_address.respond_to?(:to_str)
            @@mac_address = @@mac_address.to_str
          else
            @@mac_address = @@mac_address.to_s
          end
          @@mac_address.downcase!
          @@mac_address.strip!
        end

        # Verify that the MAC address is in the right format.
        # Nil it out if it isn't.
        unless @@mac_address.respond_to?(:scan) &&
            @@mac_address.scan(/#{(["[0-9a-f]{2}"] * 6).join(":")}/)
          @@mac_address = nil
        end
      end
      return @@mac_address
    end

    ##
    # Allows users to set the MAC address manually in cases where the MAC
    # address cannot be obtained programatically.
    def self.mac_address=(new_mac_address)
      @@mac_address = new_mac_address
    end

    # The following methods are not part of the public API,
    # and generally should not be called directly.


    ##
    # Creates a new UUID from a SHA1 or MD5 hash
    #
    # @api private
    def self.create_from_hash(hash_class, namespace, name)
      if hash_class == Digest::MD5
        version = 3
      elsif hash_class == Digest::SHA1
        version = 5
      else
        raise ArgumentError,
          "Expected Digest::SHA1 or Digest::MD5, got #{hash_class.name}."
      end
      hash = hash_class.new
      hash.update(namespace.raw)
      hash.update(name)
      hash_string = hash.to_s[0..31]
      new_uuid = self.parse("#{hash_string[0..7]}-#{hash_string[8..11]}-" +
        "#{hash_string[12..15]}-#{hash_string[16..19]}-#{hash_string[20..31]}")

      new_uuid.time_hi_and_version &= 0x0FFF
      new_uuid.time_hi_and_version |= (version << 12)
      new_uuid.clock_seq_hi_and_reserved &= 0x3F
      new_uuid.clock_seq_hi_and_reserved |= 0x80
      return new_uuid
    end

    ##
    # @api private
    def self.convert_int_to_byte_string(integer, size)
      byte_string = ""
      if byte_string.respond_to?(:force_encoding)
        byte_string.force_encoding(Encoding::ASCII_8BIT)
      end
      size.times do |i|
        byte_string << ((integer >> (((size - 1) - i) * 8)) & 0xFF)
      end
      return byte_string
    end

    ##
    # @api private
    def self.convert_byte_string_to_int(byte_string)
      if byte_string.respond_to?(:force_encoding)
        byte_string.force_encoding(Encoding::ASCII_8BIT)
      end

      integer = 0
      size = byte_string.size
      if byte_string[0].respond_to? :ord
        for i in 0...size
          integer += (byte_string[i].ord << (((size - 1) - i) * 8))
        end
      else
        for i in 0...size
          integer += (byte_string[i] << (((size - 1) - i) * 8))
        end
      end
      
      return integer
    end
  end

  ##
  # Constant Regexp that matches a UUID and captures its components.
  UUID_REGEXP = Regexp.new("^([0-9a-f]{8})-([0-9a-f]{4})-([0-9a-f]{4})-" +
                          "([0-9a-f]{2})([0-9a-f]{2})-([0-9a-f]{12})$")

  ##
  # Constant that represents the DNS namespace.
  UUID_DNS_NAMESPACE = UUID.parse("6ba7b810-9dad-11d1-80b4-00c04fd430c8")

  ##
  # Constant that represents the URL namespace.
  UUID_URL_NAMESPACE = UUID.parse("6ba7b811-9dad-11d1-80b4-00c04fd430c8")

  ##
  # Constant that represents the OID namespace.
  UUID_OID_NAMESPACE = UUID.parse("6ba7b812-9dad-11d1-80b4-00c04fd430c8")

  ##
  # Constant that represents the X500 namespace.
  UUID_X500_NAMESPACE = UUID.parse("6ba7b814-9dad-11d1-80b4-00c04fd430c8")
end