backend/app/article_fetchers/wechat.py

from __future__ import annotations

import re
from urllib.parse import parse_qs, quote, unquote, urljoin, urlparse

import requests
from bs4 import BeautifulSoup

from app.article_fetchers.base import ArticleContent, ArticleFetchError


def _clean_text(value: str) -> str:
    return re.sub(r"\s+", " ", value or "").strip()


def _element_text(element) -> str:
    return _clean_text(element.get_text(" ")) if element else ""


def _script_value(html: str, name: str) -> str:
    patterns = [
        rf'var\s+{re.escape(name)}\s*=\s*"([^"]*)"',
        rf"{re.escape(name)}\s*:\s*'([^']*)'",
    ]
    for pattern in patterns:
        match = re.search(pattern, html)
        if match:
            return match.group(1).strip()
    return ""


def parse_wechat_article_html(html: str, url: str) -> ArticleContent:
    soup = BeautifulSoup(html, "html.parser")
    title = _element_text(soup.find(id="activity-name") or soup.find("h1"))
    author = _element_text(soup.find(id="js_name"))
    published_at = _element_text(soup.find(id="publish_time"))
    content = soup.find(id="js_content")
    body = _clean_text(content.get_text("\n")) if content else ""
    if not body:
        raise ValueError("微信公众号文章正文为空，无法生成总结")

    image_urls: list[str] = []
    for image in content.find_all("img") if content else []:
        src = image.get("data-src") or image.get("src") or ""
        if src and src not in image_urls:
            image_urls.append(src)

    biz = _script_value(html, "biz")
    mid = _script_value(html, "mid")
    idx = _script_value(html, "idx")
    sn = _script_value(html, "sn")
    article_id = ":".join(part for part in [biz, mid, idx, sn] if part) or url

    return ArticleContent(
        platform="wechat_mp",
        url=url,
        article_id=article_id,
        title=title or "微信公众号文章",
        author_name=author,
        author_id=biz,
        content_text=body,
        image_urls=image_urls,
        cover_url=image_urls[0] if image_urls else "",
        published_at=published_at,
        raw_metadata={"biz": biz, "mid": mid, "idx": idx, "sn": sn},
    )


def _normalize_wechat_result_url(href: str) -> str:
    if not href:
        return ""
    absolute = urljoin("https://weixin.sogou.com", href)
    parsed = urlparse(absolute)
    query = parse_qs(parsed.query)
    for key in ("url", "target"):
        if query.get(key):
            candidate = unquote(query[key][0])
            if "mp.weixin.qq.com" in candidate:
                return candidate
    return absolute if "mp.weixin.qq.com" in absolute else ""


def parse_wechat_search_html(html: str, keyword: str, limit: int = 20) -> list[ArticleContent]:
    soup = BeautifulSoup(html, "html.parser")
    items: list[ArticleContent] = []
    seen: set[str] = set()
    for anchor in soup.find_all("a", href=True):
        url = _normalize_wechat_result_url(anchor.get("href") or "")
        if not url or url in seen:
            continue
        title = _clean_text(anchor.get_text(" "))
        if not title:
            continue
        container = anchor.find_parent(["div", "li"]) or anchor.parent
        info_nodes = container.find_all(class_=re.compile(r"(txt-info|s-p|account)")) if container else []
        info = [_clean_text(node.get_text(" ")) for node in info_nodes if _clean_text(node.get_text(" "))]
        author = info[0] if info else ""
        summary = info[-1] if len(info) > 1 else title
        seen.add(url)
        items.append(
            ArticleContent(
                platform="wechat_mp",
                url=url,
                article_id=url,
                title=title,
                author_name=author,
                content_text=summary,
                raw_metadata={"keyword": keyword, "source": "sogou_weixin"},
            )
        )
        if len(items) >= limit:
            break
    return items


class WechatArticleFetcher:
    platform = "wechat_mp"

    def fetch(self, url: str) -> ArticleContent:
        try:
            response = requests.get(url, timeout=10, headers={"User-Agent": "Mozilla/5.0"})
            response.raise_for_status()
            return parse_wechat_article_html(response.text, url)
        except ValueError:
            raise
        except Exception as exc:
            raise ArticleFetchError(f"微信公众号文章抓取失败：{exc}") from exc

    def search(self, keyword: str, limit: int = 20) -> list[ArticleContent]:
        try:
            response = requests.get(
                f"https://weixin.sogou.com/weixin?type=2&query={quote(keyword)}",
                timeout=10,
                headers={"User-Agent": "Mozilla/5.0"},
            )
            response.raise_for_status()
            return parse_wechat_search_html(response.text, keyword, limit)
        except Exception as exc:
            raise ArticleFetchError(f"微信公众号关键字查询失败：{exc}") from exc

    def fetch_publisher(self, query: str, limit: int = 20) -> list[ArticleContent]:
        return self.search(query, limit)