#!/usr/bin/env ruby
# Copyright(c) 2005 URABE, Shyouhei.
#
# Permission is hereby granted, free of  charge, to any person obtaining a copy
# of  this code, to  deal in  the code  without restriction,  including without
# limitation  the rights  to  use, copy,  modify,  merge, publish,  distribute,
# sublicense, and/or sell copies of the code, and to permit persons to whom the
# code is furnished to do so, subject to the following conditions:
#
#        The above copyright notice and this permission notice shall be
#        included in all copies or substantial portions of the code.
#
# THE  CODE IS  PROVIDED "AS  IS",  WITHOUT WARRANTY  OF ANY  KIND, EXPRESS  OR
# IMPLIED,  INCLUDING BUT  NOT LIMITED  TO THE  WARRANTIES  OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE  AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
# AUTHOR  OR  COPYRIGHT  HOLDER BE  LIABLE  FOR  ANY  CLAIM, DAMAGES  OR  OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF  OR IN CONNECTION WITH  THE CODE OR THE  USE OR OTHER  DEALINGS IN THE
# CODE.

%w[
  digest/md5
  digest/sha1
  tmpdir
].each do |f|
  require f
end

# Pure ruby UUID generator, which is compatible with RFC4122
class UUID
  # UUID epoch is 15th Oct. 1582
  UNIXEpoch = 0x01B21DD213814000 # in 100-nanoseconds resolution

  private

  def initialize str
    tmp = str.unpack "C*"
    @num = tmp.inject do |r, i|
      r * 256 | i
    end
    @num.freeze
    self.freeze
  end

  public

  def raw_bytes
    ret = String.new
    tmp = @num
    16.times do |i|
      x, y = tmp.divmod 256
      ret << y
      tmp = x
    end
    ret.reverse!
    ret
  end

  class << self
    STATE_FILE = 'ruby-uuid'

    private

    alias create new # :nodoc:
    private :create

    def mask ver, str # :nodoc:
      ver = ver & 15
      v = str[6].ord
      v &= 0b0000_1111
      v |= ver << 4
      str[6] = v.chr
      r = str[8].ord
      r &= 0b0011_1111
      r |= 0b1000_0000
      str[8] = r.chr
      str
    end

    def prand # :nodoc:
      rand 0x100000000
    end

    def read_state fp # :nodoc:
      fp.rewind
      Marshal.load fp.read
    end

    def write_state fp, c, m  # :nodoc:
      fp.rewind
      str = Marshal.dump [c, m]
      fp.write str.dup.force_encoding('UTF-8')
    end

    public

    # UUID generation using SHA1. Recommended over create_md5.
    # Namespace object is another UUID, some of them are pre-defined below.
    def new_sha1 str, namespace
      sha1 = Digest::SHA1.new
      sha1.update namespace.raw_bytes
      sha1.update str
      sum = sha1.digest
      raw = mask 5, sum[0..15]
      create raw
    end

    # UUID generation using MD5 (for backward compat.)
    def new_md5 str, namespace
      md5 = Digest::MD5.new
      md5.update namespace.raw_bytes
      md5.update str
      sum = md5.digest
      raw = mask 3, sum[0..16]
      create raw
    end

    # UUID  generation  using  random-number  generator.   From  it's  random
    # nature, there's  no warranty that  the created ID is  really universaly
    # unique.
    def new_random
      rnd = [prand, prand, prand, prand].pack "N4"
      raw = mask 4, rnd
      create raw
    end

    # create  the "version  1" UUID  with current  system clock,  current UTC
    # timestamp, and the IEEE 802 address (so-called MAC address).
    #
    # Speed notice: it's slow.  It writes  some data into hard drive on every
    # invokation. If you want to speed  this up, try remounting tmpdir with a
    # memory based filesystem  (such as tmpfs).  STILL slow?  then no way but
    # rewrite it with c :)
    def new clock=nil, time=Time.now, mac_addr=nil
      c = t = m = nil
      Dir.chdir Dir.tmpdir do
        unless FileTest.exist? STATE_FILE then
          # Generate a pseudo MAC address because we have no pure-ruby way
          # to know  the MAC  address of the  NIC this system  uses.  Note
          # that cheating  with pseudo arresses here  is completely legal:
          # see Section 4.5 of RFC4122 for details.
          sha1 = Digest::SHA1.new
          256.times do
            r = [prand].pack "N"
            sha1.update r
          end
          str = sha1.digest
          r = rand 34 # 40-6
          node = str[r, 6] || str
          node = node.bytes.to_a
          node[0] |= 0x01 # multicast bit
          node = node.pack "C*"
          k = rand 0x40000
          open STATE_FILE, 'w' do |fp|
            fp.flock IO::LOCK_EX
            write_state fp, k, node
            fp.chmod 0o777 # must be world writable
          end
        end
        open STATE_FILE, 'r+' do |fp|
          fp.flock IO::LOCK_EX
          c, m = read_state fp
          c += 1 # important; increment here
          write_state fp, c, m
        end
      end
      c = clock & 0b11_1111_1111_1111 if clock
      m = mac_addr if mac_addr
      time = Time.at time if time.is_a? Float
      case time
      when Time
        t = time.to_i * 10_000_000 + time.tv_usec * 10 + UNIXEpoch
      when Integer
        t = time + UNIXEpoch
      else
        raise TypeError, "cannot convert ``#{time}'' into Time."
      end

      tl = t & 0xFFFF_FFFF
      tm = t >> 32
      tm = tm & 0xFFFF
      th = t >> 48
      th = th & 0b0000_1111_1111_1111
      th = th | 0b0001_0000_0000_0000
      cl = c & 0b0000_0000_1111_1111
      ch = c & 0b0011_1111_0000_0000
      ch = ch >> 8
      ch = ch | 0b1000_0000
      pack tl, tm, th, ch, cl, m
    end

    # A  simple GUID  parser:  just ignores  unknown  characters and  convert
    # hexadecimal dump into 16-octet object.
    def parse obj
      str = obj.to_s.sub %r/\Aurn:uuid:/, ''
      str.gsub! %r/[^0-9A-Fa-f]/, ''
      raw = [str[0..31]].pack 'H*'
      create raw
    end

    # The 'primitive constructor' of this class
    # Note UUID.pack(uuid.unpack) == uuid
    def pack tl, tm, th, ch, cl, n
      raw = [tl, tm, th, ch, cl, n].pack "NnnCCa6"
      create raw
    end
  end

  # The 'primitive deconstructor', or the dual to pack.
  # Note UUID.pack(uuid.unpack) == uuid
  def unpack
    raw_bytes.unpack "NnnCCa6"
  end

  # The timestamp of this UUID.
  # Throws RageError if that time exceeds UNIX time range
  def time
    a = unpack
    tl = a[0]
    tm = a[1]
    th = a[2] & 0x0FFF
    t = tl
    t += tm << 32
    t += th << 48
    t -= UNIXEpoch
    tv_sec = t / 10_000_000
    t -= tv_sec * 10_000_000
    tv_usec = t / 10
    Time.at tv_sec, tv_usec
  end

  # The version of this UUID
  def version
    v = unpack[2] & 0b1111_0000_0000_0000
    v >> 12
  end

  # The clock sequence of this UUID
  def clock
    a = unpack
    ch = a[3] & 0b0001_1111
    cl = a[4]
    c = cl
    c += ch << 8
    c
  end

  # The IEEE 802 address in a hexadecimal format
  def node
    m = unpack[5].unpack 'C*'
                '%02x%02x%02x%02x%02x%02x' % m
  end
  alias mac_address node
  alias ieee802 node

  # Generate the string representation (a.k.a GUID) of this UUID
  def to_s
    a = unpack
    a[-1] = mac_address
                "%08x-%04x-%04x-%02x%02x-%s" % a
  end
  alias guid to_s

  # Convert into a RFC4122-comforming URN representation
  def to_uri
                "urn:uuid:" + self.to_s
  end
  alias urn to_uri
  alias inspect to_uri

  # Convert into 128-bit unsigned integer
  # Typically a Bignum instance, but can be a Fixnum.
  def to_int
    @num
  end
  alias to_i to_int

  # Two  UUIDs  are  said  to  be  equal if  and  only  if  their  (byte-order
  # canonicalized) integer representations are equivallent.  Refer RFC4122 for
  # details.
  def == other
    to_i == other.to_i
  end
  alias eql? ==

    # Two identical UUIDs should have same hash
    def hash
      to_i
    end

  include Comparable
  # UUIDs are comparable (don't know what benefits are there, though).
  def <=> other
    to_s <=> other.to_s
  end

  # shortcut
  def new_sha1 str
    self.class.new_sha1 str, self
  end

  # shortcut too
  def new_md5 str
    self.class.new_md5 str, self
  end

  # Pre-defined UUID Namespaces described in RFC4122 Appendix C.
  NameSpace_DNS = parse "6ba7b810-9dad-11d1-80b4-00c04fd430c8"
  NameSpace_URL = parse "6ba7b811-9dad-11d1-80b4-00c04fd430c8"
  NameSpace_OID = parse "6ba7b812-9dad-11d1-80b4-00c04fd430c8"
  NameSpace_X500 = parse "6ba7b814-9dad-11d1-80b4-00c04fd430c8"

  # The Nil UUID in RFC4122 Section 4.1.7
  Nil = parse "00000000-0000-0000-0000-000000000000"
end

module Kernel
  module_function
  def UUID str
    UUID.parse str
  end
end