"""HTTP 客户端：httpx 全局连接池 + 超时控制。

替代原 Netlify 版的 fetch + AbortController。
"""
from __future__ import annotations

from typing import Optional

import httpx

from .config import get_settings

_client: Optional[httpx.AsyncClient] = None


def get_http_client() -> httpx.AsyncClient:
    global _client
    if _client is None or _client.is_closed:
        settings = get_settings()
        timeout = httpx.Timeout(
            timeout=settings.upstream_timeout_ms / 1000.0,
            connect=10.0,
            read=settings.upstream_stream_timeout_ms / 1000.0,
        )
        _client = httpx.AsyncClient(
            timeout=timeout,
            limits=httpx.Limits(
                max_connections=100,
                max_keepalive_connections=20,
                keepalive_expiry=30.0,
            ),
            http2=False,
            follow_redirects=False,
        )
    return _client


async def close_http_client() -> None:
    global _client
    if _client is not None and not _client.is_closed:
        await _client.aclose()
    _client = None