"""DNS resolution check — pure probe returning a result dict."""
from __future__ import annotations
import asyncio
import logging
import socket

logger = logging.getLogger(__name__)


async def dns_check(address: str, expected_ip: str | None = None) -> dict:
    """Resolve `address`. Returns {is_up, resolved_ip, error_msg}.

    Up = resolution succeeded AND (no expected_ip, or at least one returned
    record matches expected_ip). resolved_ip is the first A/AAAA record.
    """
    result = await _resolve(address)
    if not result["resolved"]:
        return {"is_up": False, "resolved_ip": None, "error_msg": "Resolution failed"}

    resolved_ip = result["ip"]
    if expected_ip and expected_ip not in result["all_ips"]:
        return {
            "is_up": False,
            "resolved_ip": resolved_ip,
            "error_msg": f"Expected {expected_ip} not in {', '.join(result['all_ips'])}",
        }
    return {"is_up": True, "resolved_ip": resolved_ip, "error_msg": None}


async def _resolve(address: str) -> dict:
    """Resolve hostname. Returns all A/AAAA records; first is the resolved_ip."""
    try:
        loop = asyncio.get_running_loop()
        infos = await loop.run_in_executor(
            None, socket.getaddrinfo, address, None, socket.AF_UNSPEC, socket.SOCK_STREAM
        )
        if infos:
            all_ips = [info[4][0] for info in infos]
            return {"resolved": True, "ip": all_ips[0], "all_ips": all_ips}
        return {"resolved": False, "ip": None, "all_ips": []}
    except Exception as exc:
        logger.debug("DNS resolution failed for %s: %s", address, exc)
        return {"resolved": False, "ip": None, "all_ips": []}