import random, streams, strutils

type
  GuidVariant* {.pure.} = enum
    ncs, rfc4122, microsoft, future

  GuidVersion* {.pure.} = enum
    unknown = -1
    timeBased = 1
    dceSecurity = 2
    nameBasedMd5 = 3
    randomNumberBased = 4
    nameBasedSha1 = 5

  Guid* = array[0..15, uint8]

proc randomGuid*(): Guid =
  randomize()
  for i in 0..15: result[i] = uint8(random(255))

  # variant
  result[8] = result[8] and 0xBF'u8
  result[8] = result[8] or 0x80'u8

  # version
  result[6] = result[6] and 0x4F'u8
  result[6] = result[6] or 0x40'u8

proc variant*(self: Guid): GuidVariant =
  if (self[8] and 0x80'u8) == 0'u8: return GuidVariant.ncs
  elif (self[8] and 0xC0'u8) == 0x80'u8: return GuidVariant.rfc4122
  elif (self[8] and 0xE0'u8) == 0xC0'u8: return GuidVariant.microsoft
  else: return GuidVariant.future

proc version*(self: Guid): GuidVersion =
  case self[6] and 0xF0'u8
  of 0x10'u8: return GuidVersion.timeBased
  of 0x20'u8: return GuidVersion.dceSecurity
  of 0x30'u8: return GuidVersion.nameBasedMd5
  of 0x40'u8: return GuidVersion.randomNumberBased
  of 0x50'u8: return GuidVersion.nameBasedSha1
  else: return GuidVersion.unknown

proc `==`*(lhs, rhs: Guid): bool {.inline.} =
  for i in 0..15: result = lhs[i] == rhs[i]

proc `<`*(lhs, rhs: Guid): bool {.inline.} =
  for i in 0..15: result = lhs[i] < rhs[i]

proc `!=`*(lhs, rhs: Guid): bool {.inline.} =
  for i in 0..15: result = lhs[i] != rhs[i]

proc `>`*(lhs, rhs: Guid): bool {.inline.} =
  for i in 0..15: result = lhs[i] > rhs[i]

proc `<=`*(lhs, rhs: Guid): bool {.inline.} =
  for i in 0..15: result = lhs[i] <= rhs[i]

proc `>=`*(lhs, rhs: Guid): bool {.inline.} =
  for i in 0..15: result = lhs[i] >= rhs[i]

proc hash*(self: Guid): int {.inline.} =
  for i in self:
    result = result xor (int(i) + int(0x9E3779B9) + (result shl 6) + (result shr 2))

proc `$`*(self: Guid): string {.inline.} =
  result = ""
  for i in 0..15:
    result = result & int(self[i]).toHex(2)
    if (i == 3) or (i == 5) or (i == 7) or (i == 9):
      result = result & '-'

proc readGuid*(s: Stream): Guid {.inline.} =
  s.readData(addr(result[0]), 16)

proc writeGuid*(s: Stream, g: Guid) {.inline.} =
  s.writeData(addr(g[0]), 16)