Build lightweight AI agent admin

2026-06-08 18:14:59 +08:00
commit e164840f43
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+"""
+Link Preview API - 获取 URL 元数据用于 Embed/书签预览卡片
+"""
+import re
+from html.parser import HTMLParser
+from typing import Optional
+from urllib.parse import urljoin, urlparse
+
+import httpx
+from fastapi import APIRouter, Query
+from pydantic import BaseModel
+
+router = APIRouter(prefix="/link-preview", tags=["链接预览"])
+
+_cache: dict[str, dict] = {}
+_CACHE_MAX = 200
+
+
+class LinkPreviewResponse(BaseModel):
+    url: str
+    title: Optional[str] = None
+    description: Optional[str] = None
+    image: Optional[str] = None
+    favicon: Optional[str] = None
+    site_name: Optional[str] = None
+
+
+class _MetaParser(HTMLParser):
+    """轻量 HTML 解析器，提取 title 和 meta 中的 OG 元数据"""
+
+    def __init__(self):
+        super().__init__()
+        self.title: Optional[str] = None
+        self.og_title: Optional[str] = None
+        self.og_description: Optional[str] = None
+        self.og_image: Optional[str] = None
+        self.og_site_name: Optional[str] = None
+        self.description: Optional[str] = None
+        self.favicon: Optional[str] = None
+        self._in_title = False
+        self._title_parts: list[str] = []
+        self._done = False
+
+    def handle_starttag(self, tag: str, attrs: list[tuple[str, Optional[str]]]):
+        if self._done:
+            return
+        attrs_dict = {k.lower(): v for k, v in attrs if k}
+
+        if tag == "title":
+            self._in_title = True
+            self._title_parts = []
+            return
+
+        if tag == "meta":
+            prop = (attrs_dict.get("property") or "").lower()
+            name = (attrs_dict.get("name") or "").lower()
+            content = attrs_dict.get("content") or ""
+
+            if prop == "og:title":
+                self.og_title = content
+            elif prop == "og:description":
+                self.og_description = content
+            elif prop == "og:image":
+                self.og_image = content
+            elif prop == "og:site_name":
+                self.og_site_name = content
+            elif name == "description":
+                self.description = content
+
+        if tag == "link":
+            rel = (attrs_dict.get("rel") or "").lower()
+            href = attrs_dict.get("href") or ""
+            if "icon" in rel and href:
+                self.favicon = href
+
+    def handle_data(self, data: str):
+        if self._in_title:
+            self._title_parts.append(data)
+
+    def handle_endtag(self, tag: str):
+        if tag == "title" and self._in_title:
+            self._in_title = False
+            self.title = "".join(self._title_parts).strip()
+        if tag == "head":
+            self._done = True
+
+
+def _resolve_url(base: str, path: Optional[str]) -> Optional[str]:
+    if not path:
+        return None
+    if path.startswith(("http://", "https://", "//")):
+        return path
+    return urljoin(base, path)
+
+
+def _domain_favicon(url: str) -> str:
+    parsed = urlparse(url)
+    return f"{parsed.scheme}://{parsed.netloc}/favicon.ico"
+
+
+async def _fetch_metadata(url: str) -> dict:
+    headers = {
+        "User-Agent": "Mozilla/5.0 (compatible; ZQBot/1.0)",
+        "Accept": "text/html,application/xhtml+xml",
+        "Accept-Language": "zh-CN,zh;q=0.9,en;q=0.8",
+    }
+
+    async with httpx.AsyncClient(
+        follow_redirects=True, timeout=5.0, verify=False
+    ) as client:
+        resp = await client.get(url, headers=headers)
+        resp.raise_for_status()
+
+        content_type = resp.headers.get("content-type", "")
+        if "text/html" not in content_type and "application/xhtml" not in content_type:
+            return {"url": url}
+
+        text = resp.text[:50_000]
+
+    parser = _MetaParser()
+    try:
+        parser.feed(text)
+    except Exception:
+        pass
+
+    return {
+        "url": url,
+        "title": parser.og_title or parser.title,
+        "description": parser.og_description or parser.description,
+        "image": _resolve_url(url, parser.og_image),
+        "favicon": _resolve_url(url, parser.favicon) or _domain_favicon(url),
+        "site_name": parser.og_site_name,
+    }
+
+
+@router.get("", response_model=LinkPreviewResponse)
+async def get_link_preview(url: str = Query(..., description="要预览的 URL")):
+    """获取指定 URL 的元数据"""
+    if not re.match(r"^https?://", url):
+        url = f"https://{url}"
+
+    if url in _cache:
+        return LinkPreviewResponse(**_cache[url])
+
+    try:
+        metadata = await _fetch_metadata(url)
+    except Exception:
+        metadata = {"url": url}
+
+    if len(_cache) >= _CACHE_MAX:
+        oldest = next(iter(_cache))
+        del _cache[oldest]
+    _cache[url] = metadata
+
+    return LinkPreviewResponse(**metadata)