import ipaddress

import httpx
from starlette.requests import Request

from app.config.setting import settings
from app.core.logger import logger
from app.core.redis_crud import RedisCURD

# 归属地缓存：IP 几乎不变化，缓存 7 天可显著减少外网请求
_IP_CACHE_TTL: int = settings.IP_LOCATION_CACHE_TTL
# 硬超时（秒），避免外网查询阻塞主流程
_IP_QUERY_TIMEOUT: float = settings.IP_LOCATION_QUERY_TIMEOUT


def get_client_ip(request: Request) -> str:
    """从请求中提取客户端真实 IP（优先取反向代理透传的头部，返回空字串表示无法识别）。"""
    forwarded = request.headers.get("X-Forwarded-For", "")
    if forwarded:
        return forwarded.split(",")[0].strip()
    real_ip = request.headers.get("X-Real-IP", "")
    if real_ip:
        return real_ip.strip()
    if request.client:
        return request.client.host or ""
    return ""


class IpLocalUtil:
    """获取 IP 归属地工具类（带 Redis 缓存、硬超时、降级）。"""

    @classmethod
    def is_valid_ip(cls, ip: str) -> bool:
        try:
            ipaddress.ip_address(ip)
            return True
        except ValueError:
            return False

    @classmethod
    def is_private_ip(cls, ip: str) -> bool:
        try:
            return ipaddress.ip_address(ip).is_private
        except ValueError:
            return False

    @classmethod
    async def resolve_location_for_log(cls, redis, ip: str | None) -> str | None:
        """登录日志写入入口：仅返回可同步获取的值（内网/缓存/降级），

        外网查询由后台任务异步执行（见 ``resolve_location_async``）。
        """
        if not ip:
            return None
        if not settings.IP_LOCATION_ENABLE:
            return "内网IP" if cls.is_private_ip(ip) else "未解析(已关闭归属地查询)"
        if cls.is_private_ip(ip):
            return "内网IP"
        if redis:
            cached = await cls._cache_get(redis, ip)
            if cached is not None:
                return cached
        return "归属地查询中"

    @classmethod
    async def resolve_location_async(cls, redis, ip: str) -> str:
        """异步查询归属地（含缓存、降级、硬超时）。"""
        if not cls.is_valid_ip(ip):
            return "未知"
        if cls.is_private_ip(ip):
            return "内网IP"

        cached = await cls._cache_get(redis, ip) if redis else None
        if cached is not None:
            return cached

        result = await cls._query_with_timeout(ip)
        if redis:
            await cls._cache_set(redis, ip, result)
        return result

    @classmethod
    async def _query_with_timeout(cls, ip: str) -> str:
        """在硬超时内依次尝试多个 API，全部失败返回未知。"""
        apis = [
            ("http://ip-api.com/json", cls._parse_ipapi, {"lang": "zh-CN"}),
            ("https://whois.pconline.com.cn/ipJson.jsp", cls._parse_pconline, {"ip": ip, "json": "true"}),
        ]
        for url, parser, params in apis:
            try:
                async with httpx.AsyncClient(timeout=_IP_QUERY_TIMEOUT) as client:
                    resp = await client.get(f"{url}/{ip}" if "ip-api" in url else url, params=params)
                    if resp.status_code == 200:
                        data = resp.json() if "ip-api" in url else resp.text
                        location = parser(data)
                        if location:
                            return location
            except Exception as e:
                logger.warning(f"IP 归属地 API 失败: {url} - {e}")
        return "未知"

    @staticmethod
    def _parse_ipapi(data: dict) -> str | None:
        if data.get("status") != "success":
            return None
        parts = [data.get("country"), data.get("regionName"), data.get("city"), data.get("isp")]
        joined = "-".join(filter(None, parts))
        return joined or None

    @staticmethod
    def _parse_pconline(text: str) -> str | None:
        """解析 pconline 返回的 JSONP 文本，格式如 'if( {\"ip\":\"...\",\"pro\":\"省\",\"city\":\"市\"} )'。"""
        try:
            import re

            match = re.search(r"\{.*\}", text)
            if not match:
                return None
            import json

            data = json.loads(match.group())
            parts = [data.get("pro"), data.get("city"), data.get("addr")]
            joined = " ".join(filter(None, parts))
            return joined or None
        except Exception:
            return None

    @staticmethod
    async def _cache_get(redis, ip: str) -> str | None:
        try:
            value = await RedisCURD(redis).get(f"ip:location:{ip}")
            if value is None:
                return None
            return value.decode("utf-8") if isinstance(value, bytes) else str(value)
        except Exception:
            return None

    @staticmethod
    async def _cache_set(redis, ip: str, value: str) -> None:
        try:
            await RedisCURD(redis).set(f"ip:location:{ip}", value, expire=_IP_CACHE_TTL)
        except Exception:
            pass