"""带限速、重试、SSL 宽松回退的 HTTP 抓取。"""

import time

import requests
import urllib3

from config import MAX_RETRIES, REQUEST_DELAY, REQUEST_TIMEOUT, USER_AGENT

# 站点证书在部分环境下校验失败（curl 需 -k），先严格再回退宽松
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

_session = requests.Session()
_session.headers.update({"User-Agent": USER_AGENT})

_last_request_ts = 0.0


def _throttle() -> None:
    """简单限速：保证两次请求之间至少间隔 REQUEST_DELAY 秒。"""
    global _last_request_ts
    now = time.monotonic()
    wait = REQUEST_DELAY - (now - _last_request_ts)
    if wait > 0:
        time.sleep(wait)
    _last_request_ts = time.monotonic()


def _get(url: str, **kwargs) -> requests.Response:
    """GET，SSL 校验失败时自动回退到不校验证书。"""
    try:
        return _session.get(url, timeout=REQUEST_TIMEOUT, verify=True, **kwargs)
    except requests.exceptions.SSLError:
        return _session.get(url, timeout=REQUEST_TIMEOUT, verify=False, **kwargs)


def fetch_text(url: str) -> str:
    """抓取并返回 UTF-8 文本，带重试。"""
    last_err: Exception | None = None
    for attempt in range(1, MAX_RETRIES + 1):
        _throttle()
        try:
            resp = _get(url)
            resp.raise_for_status()
            resp.encoding = resp.apparent_encoding or "utf-8"
            return resp.text
        except requests.RequestException as e:
            last_err = e
            time.sleep(0.8 * attempt)
    raise RuntimeError(f"抓取失败 {url}: {last_err}")


def fetch_bytes(url: str) -> bytes:
    """抓取二进制（图片等），带重试。"""
    last_err: Exception | None = None
    for attempt in range(1, MAX_RETRIES + 1):
        _throttle()
        try:
            resp = _get(url)
            resp.raise_for_status()
            return resp.content
        except requests.RequestException as e:
            last_err = e
            time.sleep(0.8 * attempt)
    raise RuntimeError(f"抓取失败 {url}: {last_err}")