#!/usr/bin/env python3

import ipaddress

ZONE = ".127.10.in-addr.arpa"


def truncate(rev: str) -> str:
    assert rev.endswith(ZONE)
    rev = rev[: -len(ZONE)]
    return rev


def gen_reverse_pointers(network: str, ns: list, ds: list = [], ttl: int = -1) -> list:
    ttl = f"{ttl} " if 900 <= ttl <= 86400 else ""
    buf = list()
    net = ipaddress.IPv4Network(network, strict=True)
    assert net.prefixlen > 24
    netrev = truncate(net.reverse_pointer)
    for _ns in ns:
        buf.append(f"{netrev} {ttl}IN NS {_ns}")
    for _ds in ds:
        buf.append(f"{netrev} {ttl}IN DS {_ds}")

    for addr in net:
        cnamefr = truncate(addr.reverse_pointer)
        cnameto = f"{int.from_bytes(addr.packed, byteorder='big', signed=False) & 0xff}.{netrev}"
        buf.append(f"{cnamefr} {ttl}IN CNAME {cnameto}")
    return buf


if __name__ == "__main__":
    print(
        "\n".join(
            gen_reverse_pointers(
                "10.127.8.64/26",
                ["ns1.jerry.neo."],
                [
                    "18792 13 2 2F335456EEE70FC4833886E5EEDC28E7195E90E2A337860B3E805D5EB9F3A804"
                ],
                ttl=1500,
            )
        )
    )