Pull title, description and tags from an F95zone thread

Admin/uploader pastes a thread link and presses "Подтянуть" on the new
game and edit forms; the backend reads the public first post (no login).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

backend/app/f95.py

@@ -0,0 +1,142 @@
+"""Reads title, description and tags from a public F95zone thread (no login, first post only)."""
+import re
+import urllib.error
+import urllib.request
+from html import unescape
+from html.parser import HTMLParser
+from urllib.parse import urlparse
+
+THREAD_RE = re.compile(r"^/threads/[^/]+\.\d+/?|^/threads/\d+/?")
+UA = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124 Safari/537.36"
+MAX_BYTES = 3 * 1024 * 1024
+# first-post fields that are not part of the description itself
+STOP_LABELS = ("thread updated", "release date", "developer", "censored", "version", "os",
+               "language", "store", "genre", "installation", "changelog", "developer notes",
+               "download", "animations")
+
+
+class F95Error(Exception):
+    pass
+
+
+def validate_url(url: str) -> str:
+    p = urlparse(url.strip())
+    if p.scheme not in ("http", "https") or (p.hostname or "").lower() not in ("f95zone.to", "www.f95zone.to"):
+        raise F95Error("Ссылка должна вести на тему f95zone.to")
+    if not THREAD_RE.match(p.path):
+        raise F95Error("Это не ссылка на тему (нужен вид f95zone.to/threads/…)")
+    return f"https://f95zone.to{p.path}"
+
+
+def fetch(url: str) -> str:
+    req = urllib.request.Request(url, headers={"User-Agent": UA, "Accept-Language": "en-US,en;q=0.8"})
+    try:
+        with urllib.request.urlopen(req, timeout=15) as r:  # noqa: S310 - host is validated
+            final = urlparse(r.geturl())
+            if (final.hostname or "") not in ("f95zone.to", "www.f95zone.to"):
+                raise F95Error("Неожиданный редирект")
+            return r.read(MAX_BYTES).decode("utf-8", "replace")
+    except F95Error:
+        raise
+    except urllib.error.HTTPError as e:
+        raise F95Error(f"F95zone ответил {e.code} (тема недоступна или сайт блокирует запрос)")
+    except OSError:
+        raise F95Error("Не удалось связаться с F95zone")
+
+
+class _Parser(HTMLParser):
+    """Collects <title>-less data: og:title, tag items and the text of the first .bbWrapper."""
+
+    def __init__(self) -> None:
+        super().__init__(convert_charrefs=True)
+        self.og_title = ""
+        self.tags: list[str] = []
+        self.post: list[str] = []
+        self.template = ""
+        self._in_tag = False
+        self._tag_buf = ""
+        self._depth = 0      # div depth inside the first bbWrapper; 0 = outside
+        self._done = False
+        self._skip = 0       # inside hidden/spoiler blocks
+
+    def handle_starttag(self, tag, attrs):
+        a = dict(attrs)
+        cls = (a.get("class") or "").split()
+        if tag == "html":
+            self.template = a.get("data-template") or ""
+        elif tag == "meta" and a.get("property") == "og:title":
+            self.og_title = a.get("content") or ""
+        elif tag == "a" and "tagItem" in cls:
+            self._in_tag, self._tag_buf = True, ""
+        if self._done:
+            return
+        if self._depth == 0:
+            if tag == "div" and "bbWrapper" in cls and not self.post:
+                self._depth = 1
+            return
+        if tag == "div":
+            self._depth += 1
+            if self._skip or {"bbCodeSpoiler", "messageHide"} & set(cls):
+                self._skip += 1
+        elif tag == "br" and not self._skip:
+            self.post.append("\n")
+        elif tag in ("script", "style"):
+            self._skip += 1
+
+    def handle_endtag(self, tag):
+        if tag == "a" and self._in_tag:
+            self._in_tag = False
+            if t := self._tag_buf.strip().lower():
+                self.tags.append(t)
+        if self._depth and tag == "div":
+            if self._skip:
+                self._skip -= 1
+            self._depth -= 1
+            if self._depth == 0:
+                self._done = True
+        elif self._depth and tag in ("script", "style") and self._skip:
+            self._skip -= 1
+
+    def handle_data(self, data):
+        if self._in_tag:
+            self._tag_buf += data
+        if self._depth and not self._skip and not self._done:
+            self.post.append(data)
+
+
+def parse(html: str) -> dict:
+    p = _Parser()
+    p.feed(html)
+    if p.template == "login" or not p.post:
+        raise F95Error("Тема не найдена или закрыта для гостей")
+    title = unescape(p.og_title)
+    # "VN - Ren'Py - Hooked! [v0.6.0] [BlenderKnight]" -> "Hooked!"
+    title = re.sub(r"\s*\[[^\]]*\]", "", title)
+    title = re.sub(r"^(?:[A-Za-z0-9'’ ]{1,20} - )+", "", title).strip()
+    return {"title": title, "description": _description("".join(p.post)), "tags": sorted(set(p.tags))}
+
+
+def _description(text: str) -> str:
+    text = text.replace("​", "").replace("\xa0", " ")
+    lines = [ln.strip() for ln in text.splitlines()]
+    out: list[str] = []
+    started = False
+    for ln in lines:
+        label = ln.split(":", 1)[0].strip().lower() if ":" in ln else ""
+        if label in STOP_LABELS and started:
+            break
+        if label == "overview":
+            started = True
+            ln = ln.split(":", 1)[1].strip()
+            if not ln:
+                continue
+        elif not started and label in STOP_LABELS:
+            continue
+        started = started or bool(ln)
+        out.append(ln)
+    return re.sub(r"\n{3,}", "\n\n", "\n".join(out)).strip()
+
+
+def load(url: str) -> dict:
+    url = validate_url(url)
+    return {**parse(fetch(url)), "url": url}