# 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.
extends Node

const BYTE_MASK: int = 0b11111111


static func uuidbin():
	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):
	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():
	# 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):
	# 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]
		]
	)


var _uuid: Array


func _init(rng := RandomNumberGenerator.new()) -> void:
	_uuid = uuidbinrng(rng)


func as_array() -> Array:
	return _uuid.duplicate()


func as_dict(big_endian := true) -> Dictionary:
	if big_endian:
		return {
			"low": (_uuid[0] << 24) + (_uuid[1] << 16) + (_uuid[2] << 8) + _uuid[3],
			"mid": (_uuid[4] << 8) + _uuid[5],
			"hi": (_uuid[6] << 8) + _uuid[7],
			"clock": (_uuid[8] << 8) + _uuid[9],
			"node":
			(
				(_uuid[10] << 40)
				+ (_uuid[11] << 32)
				+ (_uuid[12] << 24)
				+ (_uuid[13] << 16)
				+ (_uuid[14] << 8)
				+ _uuid[15]
			)
		}
	else:
		return {
			"low": _uuid[0] + (_uuid[1] << 8) + (_uuid[2] << 16) + (_uuid[3] << 24),
			"mid": _uuid[4] + (_uuid[5] << 8),
			"hi": _uuid[6] + (_uuid[7] << 8),
			"clock": _uuid[8] + (_uuid[9] << 8),
			"node":
			(
				_uuid[10]
				+ (_uuid[11] << 8)
				+ (_uuid[12] << 16)
				+ (_uuid[13] << 24)
				+ (_uuid[14] << 32)
				+ (_uuid[15] << 40)
			)
		}


func as_string() -> String:
	return (
		"%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x"
		% [
			# low
			_uuid[0],
			_uuid[1],
			_uuid[2],
			_uuid[3],
			# mid
			_uuid[4],
			_uuid[5],
			# hi
			_uuid[6],
			_uuid[7],
			# clock
			_uuid[8],
			_uuid[9],
			# node
			_uuid[10],
			_uuid[11],
			_uuid[12],
			_uuid[13],
			_uuid[14],
			_uuid[15]
		]
	)


func is_equal(other) -> bool:
	# Godot Engine compares Array recursively
	# There's no need for custom comparison here.
	return _uuid == other._uuid