from __future__ import annotations

import secrets
import threading
import time
from uuid import UUID

_lock = threading.Lock()
_last_millisecond = -1
_last_random = 0
_RANDOM_MASK = (1 << 74) - 1


def new_uuid7() -> UUID:
    """Return a process-monotonic RFC 9562 UUIDv7."""
    global _last_millisecond, _last_random
    with _lock:
        millisecond = time.time_ns() // 1_000_000
        if millisecond > _last_millisecond:
            _last_millisecond = millisecond
            _last_random = secrets.randbits(74)
        else:
            millisecond = _last_millisecond
            _last_random = (_last_random + 1) & _RANDOM_MASK
            if _last_random == 0:
                _last_millisecond += 1
                millisecond = _last_millisecond
        random_a = (_last_random >> 62) & 0xFFF
        random_b = _last_random & ((1 << 62) - 1)
        integer = (millisecond & ((1 << 48) - 1)) << 80
        integer |= 0x7 << 76
        integer |= random_a << 64
        integer |= 0b10 << 62
        integer |= random_b
        return UUID(int=integer)