# MIT License
#
# Copyright (c) 2023 Xavier Sellier
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software 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 Software.
#
# THE SOFTWARE 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
# AUTHORS OR COPYRIGHT HOLDERS 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 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# Note: The code might not be as pretty it could be, since it's written
# in a way that maximizes performance. Methods are inlined and loops are avoided.
class_name UUID
const BYTE_MASK: int = 0b11111111


static func uuidbin() -> Array:
  randomize()
  # 16 random bytes with the bytes on index 6 and 8 modified
  return [
	randi() & BYTE_MASK, randi() & BYTE_MASK, randi() & BYTE_MASK, randi() & BYTE_MASK,
	randi() & BYTE_MASK, randi() & BYTE_MASK, ((randi() & BYTE_MASK) & 0x0f) | 0x40, randi() & BYTE_MASK,
	((randi() & BYTE_MASK) & 0x3f) | 0x80, randi() & BYTE_MASK, randi() & BYTE_MASK, randi() & BYTE_MASK,
	randi() & BYTE_MASK, randi() & BYTE_MASK, randi() & BYTE_MASK, randi() & BYTE_MASK,
  ]

static func uuidbinrng(rng: RandomNumberGenerator) -> Array:
  rng.randomize()
  return [
	rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK,
	rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK, ((rng.randi() & BYTE_MASK) & 0x0f) | 0x40, rng.randi() & BYTE_MASK,
	((rng.randi() & BYTE_MASK) & 0x3f) | 0x80, rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK,
	rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK, rng.randi() & BYTE_MASK,
  ]

static func v4() -> String:
  # 16 random bytes with the bytes on index 6 and 8 modified
  var b = uuidbin()

  return '%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x' % [
	# low
	b[0], b[1], b[2], b[3],

	# mid
	b[4], b[5],

	# hi
	b[6], b[7],

	# clock
	b[8], b[9],

	# clock
	b[10], b[11], b[12], b[13], b[14], b[15]
  ]

static func v4_rng(rng: RandomNumberGenerator) -> String:
  # 16 random bytes with the bytes on index 6 and 8 modified
  var b = uuidbinrng(rng)

  return '%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x' % [
	# low
	b[0], b[1], b[2], b[3],

	# mid
	b[4], b[5],

	# hi
	b[6], b[7],

	# clock
	b[8], b[9],

	# clock
	b[10], b[11], b[12], b[13], b[14], b[15]
	]