from __future__ import annotations

import hashlib

import httpx
from bs4 import BeautifulSoup

from app.services.ai_tools.schemas import FetchedEvidence


class WebFetchError(RuntimeError):
    pass


def _extract_title_and_text(html: str) -> tuple[str, str]:
    soup = BeautifulSoup(html, "html.parser")
    for tag in soup(["script", "style", "noscript", "svg"]):
        tag.decompose()
    title = soup.title.get_text(" ", strip=True) if soup.title else ""
    main = soup.find("main") or soup.find("article") or soup.body or soup
    text = main.get_text("\n", strip=True)
    lines = [line.strip() for line in text.splitlines() if line.strip()]
    return title, "\n".join(lines)


async def fetch_url_evidence(
    url: str,
    *,
    timeout_seconds: int = 20,
    max_bytes: int = 1_500_000,
) -> FetchedEvidence:
    if not url:
        raise WebFetchError("url is required")
    try:
        async with httpx.AsyncClient(
            timeout=timeout_seconds,
            follow_redirects=True,
            headers={"User-Agent": "PlanetEvidenceFetcher/1.0"},
        ) as client:
            response = await client.get(url)
            response.raise_for_status()
            content = response.content[:max_bytes]
    except httpx.HTTPError as exc:
        raise WebFetchError(f"failed to fetch page: {exc}") from exc

    title, text = _extract_title_and_text(content.decode(response.encoding or "utf-8", errors="ignore"))
    content_hash = hashlib.sha256(text.encode("utf-8")).hexdigest()
    return FetchedEvidence(
        url=url,
        final_url=str(response.url),
        title=title,
        text=text,
        content_hash=content_hash,
        extractor="beautifulsoup_basic",
    )