import string

from django.utils.crypto import get_random_string


def generate_access_code():
    ''' Generates an access code for users' payments as well as their
    fulfilment code for check-in.
    The access code will 4 characters long, which allows for 1,500,625
    unique codes, which really should be enough for anyone. '''

    length = 4
    # all upper-case letters + digits 1-9 (no 0 vs O confusion)
    chars = string.uppercase + string.digits[1:]
    # 4 chars => 35 ** 4 = 1500625 (should be enough for anyone)
    return get_random_string(length=length, allowed_chars=chars)