1 files changed, 45 insertions, 5 deletions

diff --git a/packages/backend/src/server/api/endpoints/ap/get.ts b/packages/backend/src/server/api/endpoints/ap/get.ts
index 06dd37a140..e3e68b50af 100644
--- a/packages/backend/src/server/api/endpoints/ap/get.ts
+++ b/packages/backend/src/server/api/endpoints/ap/get.ts
@@ -3,11 +3,17 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import { Injectable } from '@nestjs/common';
+import { Inject, Injectable } from '@nestjs/common';
 import ms from 'ms';
 import { Endpoint } from '@/server/api/endpoint-base.js';
 import { ApResolverService } from '@/core/activitypub/ApResolverService.js';
 import { isCollectionOrOrderedCollection, isOrderedCollection, isOrderedCollectionPage } from '@/core/activitypub/type.js';
+import { ApiError } from '@/server/api/error.js';
+import { CacheService } from '@/core/CacheService.js';
+import { UserEntityService } from '@/core/entities/UserEntityService.js';
+import { DI } from '@/di-symbols.js';
+import type { NotesRepository } from '@/models/_.js';
+import { NoteEntityService } from '@/core/entities/NoteEntityService.js';
 
 export const meta = {
 	tags: ['federation'],
@@ -22,6 +28,16 @@ export const meta = {
 	},
 
 	errors: {
+		noInputSpecified: {
+			message: 'uri, userId, or noteId must be specified.',
+			code: 'NO_INPUT_SPECIFIED',
+			id: 'b43ff2a7-e7a2-4237-ad7f-7b079563c09e',
+		},
+		multipleInputsSpecified: {
+			message: 'Only one of uri, userId, or noteId can be specified',
+			code: 'MULTIPLE_INPUTS_SPECIFIED',
+			id: 'f1aa27ed-8f20-44f3-a92a-fe073c8ca52b',
+		},
 	},
 
 	res: {
@@ -33,22 +49,46 @@ export const meta = {
 export const paramDef = {
 	type: 'object',
 	properties: {
-		uri: { type: 'string' },
+		uri: { type: 'string', nullable: true },
+		userId: { type: 'string', format: 'misskey:id', nullable: true },
+		noteId: { type: 'string', format: 'misskey:id', nullable: true },
 		expandCollectionItems: { type: 'boolean' },
 		expandCollectionLimit: { type: 'integer', nullable: true },
 		allowAnonymous: { type: 'boolean' },
 	},
-	required: ['uri'],
 } as const;
 
 @Injectable()
 export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-disable-line import/no-default-export
 	constructor(
+		@Inject(DI.notesRepository)
+		private readonly notesRepository: NotesRepository,
+
+		private readonly cacheService: CacheService,
+		private readonly userEntityService: UserEntityService,
+		private readonly noteEntityService: NoteEntityService,
 		private apResolverService: ApResolverService,
 	) {
-		super(meta, paramDef, async (ps, me) => {
+		super(meta, paramDef, async (ps) => {
+			if (ps.uri && ps.userId && ps.noteId) {
+				throw new ApiError(meta.errors.multipleInputsSpecified);
+			}
+
+			let uri: string;
+			if (ps.uri) {
+				uri = ps.uri;
+			} else if (ps.userId) {
+				const user = await this.cacheService.findUserById(ps.userId);
+				uri = user.uri ?? this.userEntityService.genLocalUserUri(ps.userId);
+			} else if (ps.noteId) {
+				const note = await this.notesRepository.findOneByOrFail({ id: ps.noteId });
+				uri = note.uri ?? this.noteEntityService.genLocalNoteUri(ps.noteId);
+			} else {
+				throw new ApiError(meta.errors.noInputSpecified);
+			}
+
 			const resolver = this.apResolverService.createResolver();
-			const object = await resolver.resolve(ps.uri, ps.allowAnonymous ?? false);
+			const object = await resolver.resolve(uri, ps.allowAnonymous ?? false);
 
 			if (ps.expandCollectionItems && isCollectionOrOrderedCollection(object)) {
 				const items = await resolver.resolveCollectionItems(object, ps.expandCollectionLimit, ps.allowAnonymous ?? false);