feat: add event watcher

backend/src/userbot/modules/watches/evaluator.py

@@ -0,0 +1,24 @@
+import re
+from typing import Any
+
+KIND_KEYWORD = "keyword"
+KIND_PEER_ONLINE = "peer_online"
+
+
+def match_keyword(text: str, chat_id: int, params: dict[str, Any]) -> bool:
+    target_chat = params.get("chat_id")
+    if target_chat is not None and target_chat != chat_id:
+        return False
+    pattern = params.get("pattern")
+    if not pattern:
+        return False
+    if params.get("regex"):
+        try:
+            return re.search(pattern, text) is not None
+        except re.error:
+            return False
+    return pattern.casefold() in text.casefold()
+
+
+def match_peer_online(peer_id: int, params: dict[str, Any]) -> bool:
+    return params.get("peer_id") == peer_id