from typing import Optional
from urllib.parse import urljoin
import httpx
from common.security import is_safe_url

DEFAULT_USER_AGENT = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36 bangwen/1.0"
MAX_REDIRECTS = 5


class PoliteFetcher:
    def __init__(self, timeout: float = 15.0, verify: bool | str = True):
        self.headers = {
            "User-Agent": DEFAULT_USER_AGENT,
            "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
            "Accept-Language": "zh-CN,zh;q=0.9,en;q=0.8",
        }
        self.client = httpx.Client(
            headers=self.headers,
            timeout=timeout,
            follow_redirects=False,
            verify=verify,
        )

    def get_text(
        self,
        url: str,
        allowed_domains: Optional[list[str]] = None,
        start_host: Optional[str] = None,
    ) -> str:
        current_url = url
        for _ in range(MAX_REDIRECTS):
            if not is_safe_url(current_url, allowed_domains, start_host):
                raise ValueError(f"Unsafe request URL blocked: {current_url}")

            resp = self.client.get(current_url)
            if resp.is_redirect and "location" in resp.headers:
                next_url = urljoin(current_url, resp.headers["location"])
                current_url = next_url
                continue

            resp.raise_for_status()

            content_type = resp.headers.get("content-type", "").lower()
            if (
                "gbk" in content_type
                or "gb2312" in content_type
                or "gb18030" in content_type
            ):
                return resp.content.decode("gb18030", errors="replace")

            try:
                return resp.text
            except UnicodeDecodeError:
                return resp.content.decode("gb18030", errors="replace")

        raise httpx.TooManyRedirects(
            f"Exceeded max redirects ({MAX_REDIRECTS}) for {url}"
        )

    def close(self):
        self.client.close()