import base64
import time
import secrets
import threading


class RandomUidGenerator:

    __UID_VERSION = 0b10

    def __init__(self):
        self.__lock = threading.Lock()
        self.__timestamp_ms = None
        self.__seed = None
        self.__counter = None

    def generate(self, now_dt = None):
        now_ms = (RandomUidGenerator.__now_ms()
                if now_dt is None
                else int(now_dt.timestamp() * 1000))
        timestamp, counter = self.__advance(now_ms)
        return RandomUidGenerator.__encode(timestamp, counter)

    def __advance(self, now_ms):
        with self.__lock:
            if self.__timestamp_ms is None or now_ms > self.__timestamp_ms:
                self.__reseed(now_ms)
            else:
                self.__counter = self.__counter + 1 & (1 << 33) - 1
                if self.__counter == self.__seed:
                    self.__reseed(self.__timestamp_ms + 1)
            return self.__timestamp_ms, self.__counter

    def __reseed(self, timestamp_ms):
        if timestamp_ms >> 45:
            raise ValueError(f"Timestamp out of range: {timestamp_ms}")
        self.__counter = self.__seed = secrets.randbits(33)
        self.__timestamp_ms = timestamp_ms

    @staticmethod
    def __now_ms():
        return time.time_ns() // 1_000_000

    @staticmethod
    def __encode(timestamp, counter):
        uid_mid = counter >> 13
        uid_low = RandomUidGenerator.__UID_VERSION << 13 | counter & (1 << 13) - 1
        uid_bigint = timestamp << 35 | uid_mid << 15 | uid_low
        return base64.b32hexencode(uid_bigint.to_bytes(10)).decode('utf-8').lower()


import datetime
import pytz
generator = RandomUidGenerator()
print(generator.generate(pytz.timezone('America/Chicago').localize(datetime.datetime(2010, 4, 1, 1, 28, 38, 422000))))
print(generator.generate())
print(generator.generate())