#!/usr/bin/env python3
import sys
from ipaddress import IPv4Address, ip_network, IPv4Network
from pathlib import Path

import toml
from rfc2317 import gen_reverse_pointers

RESOLVE_FILE = Path("dns", "db.10.127")
ROUTE_FILE = Path("route")
RFC2317_FILE = Path("dns", "rfc2317.toml")

def iter_route(route_type: str):
    items = []
    for f in ROUTE_FILE.iterdir():
        routes = toml.loads(f.read_text())
        items.extend(
            (entity["name"], ip_network(route).network_address)
            for route, entity in routes.items()
            if entity["type"] == route_type and isinstance(ip_network(route), IPv4Network)
        )
    routes = []
    remove = []
    for item in items[::-1]:
        if item[1] in routes:
            remove.append(item)
        else:
            routes.append(item[1])
    for i in remove:
        items.remove(i)
    return sorted(items, key=lambda item: item[1])

def iter_rfc2317_entry():
    entries = toml.loads(RFC2317_FILE.read_text())
    for (route, attributes) in entries.items():
        ns = attributes.get('ns')
        yield(route, ns)

def main():
    orignal = RESOLVE_FILE.read_text()
    orignal = orignal[: orignal.find("\n; AUTOGENERATED")]
    records = [orignal, "; AUTOGENERATED", "", "; Loopback Addresses"]
    for name, address in iter_route("loopback"):
        if isinstance(address, IPv4Address):
            pointer = address.reverse_pointer.replace(".127.10.in-addr.arpa", "")
            records.append("%s\tIN\tPTR\t%s.neo." % (pointer, name))

    records.extend(("", "; rfc2317"))
    for route, ns in iter_rfc2317_entry():
        records.extend(gen_reverse_pointers(route, ns))
        records.append("")

    RESOLVE_FILE.write_text("\n".join(records))


if __name__ == "__main__":
    main()