"""Resolve Nexus center IP for Baota API whitelist."""

from __future__ import annotations

import ipaddress
import logging
import socket
from urllib.parse import urlparse

from server.config import settings

logger = logging.getLogger("nexus.btpanel.source_ip")


def _is_ip(value: str) -> bool:
    try:
        ipaddress.ip_address(value.strip())
        return True
    except ValueError:
        return False


def _host_from_url(url: str) -> str | None:
    parsed = urlparse(url.strip())
    host = (parsed.hostname or "").strip()
    return host or None


def resolve_center_ip_from_dns(host: str) -> str | None:
    if not host:
        return None
    if _is_ip(host):
        return host
    try:
        infos = socket.getaddrinfo(host, None, type=socket.SOCK_STREAM)
        for info in infos:
            addr = info[4][0]
            if _is_ip(addr):
                return addr
    except OSError as exc:
        logger.warning("bt panel source ip dns failed host=%s: %s", host, exc)
    return None


def get_bt_panel_source_ip() -> str | None:
    """Center outbound IP for Baota ``limit_addr`` (settings → API_BASE_URL DNS)."""
    explicit = (getattr(settings, "BT_PANEL_SOURCE_IP", None) or "").strip()
    if explicit and _is_ip(explicit):
        return explicit

    base = (settings.API_BASE_URL or "").strip()
    host = _host_from_url(base) if base else None
    if host:
        resolved = resolve_center_ip_from_dns(host)
        if resolved:
            return resolved

    return None