#!/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_class_method :new

	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
		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

		private :mask, :prand

		# UUID generation using SHA1. Recommended over create_md5.
		# Namespace object is another UUID, some of them are pre-defined below.
		def create_sha1 str, namespace
			sha1 = Digest::SHA1.new
			sha1.update namespace.raw_bytes
			sha1.update str
			sum = sha1.digest
			raw = mask 5, sum[0..15]
			new raw
		end

		# UUID generation using MD5 (for backward compat.)
		def create_md5 str, namespace
			md5 = Digest::MD5.new
			md5.update namespace.raw_bytes
			md5.update str
			sum = md5.digest
			raw = mask 3, sum[0..16]
			new 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 create_random
			rnd = [prand, prand, prand, prand].pack "N4"
			raw = mask 4, rnd
			new raw
		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
		end

		private :read_state, :write_state
		STATE_FILE = 'ruby-uuid'

		# 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 create *args

      if args[0].class.to_s == "Hash"
        args= Hash[*args]
        clock   = args[:clock] || nil
        time    = args[:time]  || Time.now
        mac_addr= args[:mac]   || nil
      else
        clock   = args[0] || nil
        time    = args[1] || Time.now
        mac_addr= args[2] || nil
      end

			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
					ary = sha1.digest.bytes.to_a
					node = ary.last 6
					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*'
			new 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"
			new 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

	# 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

# Local Variables:
# mode: ruby
# coding: utf-8
# indent-tabs-mode: t
# tab-width: 3
# ruby-indent-level: 3
# fill-column: 79
# default-justification: full
# End:
# vi: ts=3 sw=3