core: allow cross-domain problem search

packages/hydrooj/src/model/domain.ts

@@ -275,6 +275,11 @@ class DomainModel {
     static async getUnion(domainId: string) {
         return await collUnion.findOne({ _id: domainId });
     }
+
+    @ArgMethod
+    static async searchUnion(query) {
+        return await collUnion.find(query).toArray();
+    }
 }
 
 bus.once('app/started', async () => {

packages/hydrooj/src/model/problem.ts

@@ -16,6 +16,7 @@ import {
 import { buildProjection } from '../utils';
 import { STATUS } from './builtin';
 import * as document from './document';
+import DomainModel from './domain';
 import storage from './storage';
 
 export interface ProblemDoc extends Document { }
@@ -132,6 +133,30 @@ export class ProblemModel {
         return document.getMulti(domainId, document.TYPE_PROBLEM, query, projection).sort({ sort: 1 });
     }
 
+    static async list(
+        domainId: string, query: FilterQuery<ProblemDoc>,
+        projection = ProblemModel.PROJECTION_LIST, page: number, pageSize: number,
+    ): Promise<[ProblemDoc[], number, number]> {
+        const union = await DomainModel.getUnion(domainId);
+        const domainIds = [domainId];
+        if (union?.problem) domainIds.push(...union.union);
+        let count = 0;
+        const pdocs = [];
+        for (const id of domainIds) {
+            // TODO enhance performance
+            // eslint-disable-next-line no-await-in-loop
+            const ccount = await document.getMulti(id, document.TYPE_PROBLEM, query).count();
+            if (pdocs.length < pageSize && (page - 1) * pageSize - count <= ccount) {
+                // eslint-disable-next-line no-await-in-loop
+                pdocs.push(...await document.getMulti(id, document.TYPE_PROBLEM, query, projection)
+                    .sort({ sort: 1, docId: 1 })
+                    .skip(Math.max((page - 1) * pageSize - count, 0)).limit(pageSize - pdocs.length).toArray());
+            }
+            count += ccount;
+        }
+        return [pdocs, Math.ceil(count / pageSize), count];
+    }
+
     static getStatus(domainId: string, docId: number, uid: number) {
         return document.getStatus(domainId, document.TYPE_PROBLEM, docId, uid);
     }