import os
import numpy as np


def group_seed():
    bd_env_var = os.getenv("BIRTHDAYS")

    # If no birthdays are set, complain and exit
    if not bd_env_var:
        print("Environment variable BIRTHDAYS is missing")
        exit(-1)

    # convert birthdays to ints
    birthdays = [int(bd) for bd in bd_env_var.split(",")]

    # multiply them to get the group seed
    seed = 1
    for bd in birthdays:
        seed *= bd

    return seed


rng = np.random.default_rng(group_seed())