#!/usr/bin/python3 -Bsu

## Copyright (C) 2026 - 2026 ENCRYPTED SUPPORT LLC <adrelanos@whonix.org>
## See the file COPYING for copying conditions.

import sys
import secrets
from typing import NoReturn

def print_usage() -> None:
    """
    Print usage information.
    """

    print("Usage: random-between <lower_bound> <upper_bound>", file=sys.stderr)

def main() -> NoReturn:
    """
    Gets a securely generated bounded random number and prints its decimal
    representation to stdout. Both bounds are inclusive.
    """

    if len(sys.argv) != 3:
        print_usage()
        sys.exit(1)

    try:
        lower_bound: int = int(sys.argv[1])
    except Exception:
        print("ERROR: Lower bound is not an integer!", file=sys.stderr)
        sys.exit(1)

    try:
        upper_bound: int = int(sys.argv[2])
    except Exception:
        print("ERROR: Upper bound is not an integer!", file=sys.stderr)
        sys.exit(1)

    if lower_bound > upper_bound:
        print(
            "ERROR: Lower bound must be less than or equal to upper bound!",
            file=sys.stderr,
        )
        sys.exit(1)

    ## secrets.randbelow() excludes the upper bound, so we need to add 1 to
    ## get a number that is between the upper and lower bound inclusive.
    secret_bound: int = (upper_bound - lower_bound) + 1
    secret_val: int = secrets.randbelow(secret_bound)
    print(secret_val + lower_bound)

if __name__ == "__main__":
    main()
