from __future__ import annotations

import asyncio
import os
import re
from datetime import datetime, timezone

from .state import NetworkState

# dnsmasq style: "query[A] example.com from 192.168.88.10"
DNS_QUERY_RE = re.compile(r"query\[[^\]]+\]\s+(?P<qname>\S+)\s+from\s+(?P<src_ip>\d+\.\d+\.\d+\.\d+)")


async def tail_dns_log(state: NetworkState, path: str) -> None:
    if not path:
        return
    if not os.path.isfile(path):
        return

    with open(path, "r", encoding="utf-8", errors="ignore") as f:
        f.seek(0, os.SEEK_END)
        while True:
            line = f.readline()
            if not line:
                await asyncio.sleep(0.5)
                continue

            m = DNS_QUERY_RE.search(line)
            if not m:
                continue
            src_ip = m.group("src_ip")
            qname = m.group("qname")
            await state.add_dns_event(src_ip=src_ip, qname=qname, answers=[], ts=datetime.now(timezone.utc))