功能：实现 Group_Horse_Racing 群赛马插件

- 新增群赛马游戏插件，支持多人参与赛马竞猜

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

danding_bot/plugins/group_horse_racing/message_service.py

@@ -0,0 +1,65 @@
+import asyncio
+from typing import Optional, Callable
+from datetime import datetime, timedelta
+
+from .config import Config
+
+
+class MessageService:
+    def __init__(self, config: Config):
+        self.config = config
+        self.pending_recalls: dict[str, list[asyncio.Task]] = {}
+
+    async def send_with_recall(
+        self,
+        scope: str,
+        message_type: str,
+        send_func: Callable,
+        *args,
+        **kwargs,
+    ) -> Optional[str]:
+        """Send message and schedule recall if configured."""
+        try:
+            message_id = await send_func(*args, **kwargs)
+            if not message_id:
+                return None
+
+            recall_time = self.config.MESSAGE_RECALL.get(message_type, 0)
+            if recall_time > 0:
+                task = asyncio.create_task(
+                    self._schedule_recall(scope, message_id, recall_time, send_func)
+                )
+                if scope not in self.pending_recalls:
+                    self.pending_recalls[scope] = []
+                self.pending_recalls[scope].append(task)
+
+            return message_id
+        except Exception as e:
+            return None
+
+    async def _schedule_recall(
+        self,
+        scope: str,
+        message_id: str,
+        delay: int,
+        recall_func: Callable,
+    ):
+        """Schedule message recall."""
+        try:
+            await asyncio.sleep(delay)
+            await recall_func(message_id)
+        except Exception:
+            pass
+
+    def clear_pending_recalls(self, scope: str):
+        """Cancel all pending recall tasks for a scope."""
+        if scope in self.pending_recalls:
+            for task in self.pending_recalls[scope]:
+                if not task.done():
+                    task.cancel()
+            del self.pending_recalls[scope]
+
+    def clear_all_recalls(self):
+        """Cancel all pending recall tasks."""
+        for scope in list(self.pending_recalls.keys()):
+            self.clear_pending_recalls(scope)