separate SkRateLimiterService from RateLimiterService and update all usages

packages/backend/src/misc/rate-limit-utils.ts

@@ -0,0 +1,21 @@
+/*
+ * SPDX-FileCopyrightText: hazelnoot and other Sharkey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { FastifyReply } from 'fastify';
+import { LimitInfo } from '@/server/api/SkRateLimiterService.js';
+
+export function sendRateLimitHeaders(reply: FastifyReply, info: LimitInfo): void {
+	// Number of seconds until the limit has fully reset.
+	reply.header('X-RateLimit-Clear', info.fullResetSec.toString());
+	// Number of calls that can be made before being limited.
+	reply.header('X-RateLimit-Remaining', info.remaining.toString());
+
+	if (info.blocked) {
+		// Number of seconds to wait before trying again. Left for backwards compatibility.
+		reply.header('Retry-After', info.resetSec.toString());
+		// Number of milliseconds to wait before trying again.
+		reply.header('X-RateLimit-Reset', info.resetMs.toString());
+	}
+}