"""Seed scheme.

instance_seed = SHA1(f"{base_seed}|{family}|{instance_index}") mod 2**31
RNG fixed to numpy.random.default_rng (PCG64). `family` is the dotted family
name (e.g. "positives.clear_large_training").
"""

from __future__ import annotations

import hashlib

import numpy as np

DEFAULT_BASE_SEED = 20260609
RNG_NAME = "numpy.random.default_rng"


def instance_seed(base_seed: int, family: str, instance_index: int) -> int:
    digest = hashlib.sha1(f"{base_seed}|{family}|{instance_index}".encode("utf-8")).hexdigest()
    return int(digest, 16) % (2 ** 31)


def rng_for(base_seed: int, family: str, instance_index: int) -> np.random.Generator:
    return np.random.default_rng(instance_seed(base_seed, family, instance_index))