#!/usr/bin/env python3
"""IP helper functions for the intrusion-detection system."""

from __future__ import annotations

import ipaddress
from typing import Iterable

from whitelists import WHITELIST_NETS as _WHITELIST_NETS


def parse_ip(value: str):
    """Return an ip_address object, or None if `value` is not an IP."""
    try:
        return ipaddress.ip_address(value)
    except (ValueError, TypeError):
        return None


def ip_version(value: str) -> int | None:
    addr = parse_ip(value)
    return addr.version if addr else None


def is_ipv6(value: str) -> bool:
    return ip_version(value) == 6


def is_ipv4(value: str) -> bool:
    return ip_version(value) == 4


def whitelist_of(value: str) -> str | None:
    """Return the whitelist name an IP belongs to, else None."""
    addr = parse_ip(value)
    if addr is None:
        return None
    for name, nets in _WHITELIST_NETS.items():
        for net in nets:
            if addr.version == net.version and addr in net:
                return name
    return None


def is_whitelisted(value: str) -> bool:
    return whitelist_of(value) is not None


def sort_ips(ips: Iterable[str]) -> list[str]:
    """Numeric sort, IPv4 before IPv6, unparseable last."""
    def key(ip: str):
        addr = parse_ip(ip)
        if addr is None:
            return (9, b"", ip)
        return (addr.version, addr.packed, "")
    return sorted(ips, key=key)


def split_versions(ips: Iterable[str]) -> tuple[list[str], list[str]]:
    """Split an IP iterable into (sorted IPv4, sorted IPv6)."""
    ips = list(ips)
    return (sort_ips(ip for ip in ips if is_ipv4(ip)),
            sort_ips(ip for ip in ips if is_ipv6(ip)))