core: support mention notification

packages/hydrooj/src/model/message.ts

@@ -10,6 +10,7 @@ const coll = db.collection('message');
 class MessageModel {
     static FLAG_UNREAD = 1;
     static FLAG_ALERT = 2;
+    static FLAG_RICHTEXT = 4;
 
     @ArgMethod
     static async send(
@@ -33,7 +34,7 @@ class MessageModel {
 
     @ArgMethod
     static async getByUser(uid: number): Promise<MessageDoc[]> {
-        return await coll.find({ $or: [{ from: uid }, { to: uid }] }).sort('_id', 1).toArray();
+        return await coll.find({ $or: [{ from: uid }, { to: uid }] }).sort('_id', 1).limit(1000).toArray();
     }
 
     static async getMany(query: FilterQuery<MessageDoc>, sort: any, page: number, limit: number): Promise<MessageDoc[]> {