core: import: support using extracted folder

packages/hydrooj/src/model/problem.ts

@@ -407,7 +407,9 @@ export class ProblemModel {
     }
 
     static async import(domainId: string, filepath: string, operator: number) {
-        const tmpdir = path.join(os.tmpdir(), 'hydro', `${Math.random()}.import`);
+        let tmpdir = '';
+        if (filepath.endsWith('.zip')) {
+            tmpdir = path.join(os.tmpdir(), 'hydro', `${Math.random()}.import`);
             let zip: AdmZip;
             try {
                 zip = new AdmZip(filepath);
@@ -420,6 +422,11 @@ export class ProblemModel {
                     resolve(null);
                 });
             });
+        } else if (fs.statSync(filepath).isDirectory()) {
+            tmpdir = filepath;
+        } else {
+            throw new ValidationError('file', null, 'Invalid file');
+        }
         try {
             const problems = await fs.readdir(tmpdir, { withFileTypes: true });
             for (const p of problems) {