1 files changed, 119 insertions, 0 deletions
diff --git a/packages/backend/src/core/RelayService.ts b/packages/backend/src/core/RelayService.ts
new file mode 100644
index 0000000000..c1d85e8b48
--- /dev/null
+++ b/packages/backend/src/core/RelayService.ts
@@ -0,0 +1,119 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { IsNull } from 'typeorm';
+import type { ILocalUser, User } from '@/models/entities/User.js';
+import { RelaysRepository, UsersRepository } from '@/models/index.js';
+import { IdService } from '@/core/IdService.js';
+import { Cache } from '@/misc/cache.js';
+import type { Relay } from '@/models/entities/Relay.js';
+import { QueueService } from '@/core/QueueService.js';
+import { CreateSystemUserService } from '@/core/CreateSystemUserService.js';
+import { ApRendererService } from '@/core/remote/activitypub/ApRendererService.js';
+import { DI } from '@/di-symbols.js';
+
+const ACTOR_USERNAME = 'relay.actor' as const;
+
+@Injectable()
+export class RelayService {
+	#relaysCache: Cache<Relay[]>;
+
+	constructor(
+		@Inject(DI.usersRepository)
+		private usersRepository: UsersRepository,
+
+		@Inject(DI.relaysRepository)
+		private relaysRepository: RelaysRepository,
+
+		private idService: IdService,
+		private queueService: QueueService,
+		private createSystemUserService: CreateSystemUserService,
+		private apRendererService: ApRendererService,
+	) {
+		this.#relaysCache = new Cache<Relay[]>(1000 * 60 * 10);
+	}
+
+	async #getRelayActor(): Promise<ILocalUser> {
+		const user = await this.usersRepository.findOneBy({
+			host: IsNull(),
+			username: ACTOR_USERNAME,
+		});
+	
+		if (user) return user as ILocalUser;
+	
+		const created = await this.createSystemUserService.createSystemUser(ACTOR_USERNAME);
+		return created as ILocalUser;
+	}
+
+	public async addRelay(inbox: string): Promise<Relay> {
+		const relay = await this.relaysRepository.insert({
+			id: this.idService.genId(),
+			inbox,
+			status: 'requesting',
+		}).then(x => this.relaysRepository.findOneByOrFail(x.identifiers[0]));
+	
+		const relayActor = await this.#getRelayActor();
+		const follow = await this.apRendererService.renderFollowRelay(relay, relayActor);
+		const activity = this.apRendererService.renderActivity(follow);
+		this.queueService.deliver(relayActor, activity, relay.inbox);
+	
+		return relay;
+	}
+
+	public async removeRelay(inbox: string): Promise<void> {
+		const relay = await this.relaysRepository.findOneBy({
+			inbox,
+		});
+	
+		if (relay == null) {
+			throw new Error('relay not found');
+		}
+	
+		const relayActor = await this.#getRelayActor();
+		const follow = this.apRendererService.renderFollowRelay(relay, relayActor);
+		const undo = this.apRendererService.renderUndo(follow, relayActor);
+		const activity = this.apRendererService.renderActivity(undo);
+		this.queueService.deliver(relayActor, activity, relay.inbox);
+	
+		await this.relaysRepository.delete(relay.id);
+	}
+
+	public async listRelay(): Promise<Relay[]> {
+		const relays = await this.relaysRepository.find();
+		return relays;
+	}
+	
+	public async relayAccepted(id: string): Promise<string> {
+		const result = await this.relaysRepository.update(id, {
+			status: 'accepted',
+		});
+	
+		return JSON.stringify(result);
+	}
+
+	public async relayRejected(id: string): Promise<string> {
+		const result = await this.relaysRepository.update(id, {
+			status: 'rejected',
+		});
+	
+		return JSON.stringify(result);
+	}
+
+	public async deliverToRelays(user: { id: User['id']; host: null; }, activity: any): Promise<void> {
+		if (activity == null) return;
+	
+		const relays = await this.#relaysCache.fetch(null, () => this.relaysRepository.findBy({
+			status: 'accepted',
+		}));
+		if (relays.length === 0) return;
+	
+		// TODO
+		//const copy = structuredClone(activity);
+		const copy = JSON.parse(JSON.stringify(activity));
+		if (!copy.to) copy.to = ['https://www.w3.org/ns/activitystreams#Public'];
+	
+		const signed = await this.apRendererService.attachLdSignature(copy, user);
+	
+		for (const relay of relays) {
+			this.queueService.deliver(user, signed, relay.inbox);
+		}
+	}
+}