chore: do not store text in memory

bot/mongodb/__init__.py

@@ -1 +1 @@
-from .load_db import load_chat_messages_from_db
+from .load_db import load_chat_messages_from_db, read_random_message_from_collection

bot/mongodb/load_db.py

@@ -54,7 +54,7 @@ def write_deleted_message_to_collection(
         return []
 
 
-def read_message_from_collection(
+def read_messages_from_collection(
     database="discord_bot",
     collection="messages",
 ):
@@ -91,10 +91,55 @@ def read_message_from_collection(
         return []
 
 
+def read_random_message_from_collection(
+    database="discord_bot",
+    collection="messages",
+):
+    """
+    Loads a random chat message from MongoDB.
+
+    Args:
+        database (str): Name of the MongoDB database
+        collection (str): Name of the collection
+
+    Returns:
+        str or None: random message string, or None if collection is empty
+    """
+    mongo_uri = get_mongodb_uri()
+
+    try:
+        with MongoClient(mongo_uri) as client:
+            db = client[database]
+            col = db[collection]
+
+            logger.debug(
+                f"Connecting to MongoDB at {mongo_uri}, DB='{database}', Collection='{collection}'"
+            )
+
+            # Use aggregation with $sample to get a random document
+            pipeline = [{"$sample": {"size": 1}}]
+
+            cursor = col.aggregate(pipeline)
+            # almost random
+            random_docs = list(cursor)
+
+            if random_docs and "message" in random_docs[0]:
+                message = random_docs[0]["message"]
+                logger.info(f"Loaded random message from MongoDB: {message[:100]}...")
+                return message
+
+            logger.warning("No messages found in collection")
+            return None
+
+    except Exception as e:
+        logger.error(f"Failed to load random message from MongoDB: {e}")
+        return None
+
+
 def load_chat_messages_from_db():
     messages = []
 
-    messages = read_message_from_collection()
+    messages = read_messages_from_collection()
     if not messages:
         logger.warning("messages collection is empty after loading from MongoDB!")