from __future__ import annotations
import random
import secrets
CONFUSE_CHARS = 'OoIl01'

def make_rng(seed: int | None=None) -> tuple[random.Random, int]:
    if seed is None:
        seed = secrets.randbits(63)
    return (random.Random(seed), seed)

def gen_name(rng: random.Random, length: int | None=None, used: set[str] | None=None) -> str:
    if length is None:
        length = rng.randint(12, 20)
    used = used or set()
    for _ in range(64):
        name = '_' + ''.join((rng.choice(CONFUSE_CHARS) for _ in range(length)))
        if name not in used:
            return name
    while True:
        name = '_' + ''.join((rng.choice(CONFUSE_CHARS) for _ in range(length + rng.randint(1, 4))))
        if name not in used:
            return name

def gen_bytes(rng: random.Random, length: int) -> bytes:
    return bytes((rng.randrange(256) for _ in range(length)))