add rate limiting as a property that always appears in all responses, instead of only in errors

Author: gabrielmfern

src/interfaces.ts

@@ -1,3 +1,5 @@
+import { RateLimit } from './rate-limiting';
+
 export const RESEND_ERROR_CODES_BY_KEY = {
   missing_required_field: 422,
   invalid_idempotency_key: 400,
@@ -19,35 +21,22 @@ export const RESEND_ERROR_CODES_BY_KEY = {
 
 export type RESEND_ERROR_CODE_KEY = keyof typeof RESEND_ERROR_CODES_BY_KEY;
 
-export type ErrorResponse =
+export type ErrorResponse = {
+  message: string;
+  name: RESEND_ERROR_CODE_KEY;
+};
+
+export type Response<Data> = (
   | {
-      message: string;
-      name: Exclude<RESEND_ERROR_CODE_KEY, 'rate_limit_exceeded'>;
+      data: Data;
+      error: null;
     }
   | {
-      name: Extract<RESEND_ERROR_CODE_KEY, 'rate_limit_exceeded'>;
-      message: string;
-      /**
-       * Information to help you with remediation of the error, for example,
-       * waiting for `retry_after` before retrying a rate limited request.
-       */
-      remediation: {
-        /**
-         * Time in seconds after which the request can be retried.
-         */
-        retry_after: number;
-
-        /**
-         * The number of requests allowed per {@member reset}.
-         */
-        limit: number;
-        /**
-         * Time in seconds for the limit
-         */
-        reset: number;
-
-        policy: string;
-      };
-    };
+      data: null;
+      error: ErrorResponse;
+    }
+) & {
+  rateLimiting: RateLimit;
+};
 
 export type Tag = { name: string; value: string };

src/rate-limiting.ts

@@ -0,0 +1,28 @@
+export type RateLimit = {
+  limit: number;
+  remainingRequests: number;
+  shouldResetAfter: number;
+};
+
+export function parseRateLimit(headers: Headers): RateLimit | undefined {
+  const limitHeader = headers.get('ratelimit-limit');
+  const remainingHeader = headers.get('ratelimit-remaining');
+  const resetHeader = headers.get('ratelimit-reset');
+
+  if (!limitHeader || !remainingHeader || !resetHeader) {
+    console.warn(
+      "The rate limit headers are not present in the response, something must've gone wrong, please email us at support@resend.com",
+    );
+    return undefined;
+  }
+
+  const limit = Number.parseInt(limitHeader, 10);
+  const remaining = Number.parseInt(remainingHeader, 10);
+  const reset = Number.parseInt(resetHeader, 10);
+
+  return {
+    limit,
+    remainingRequests: remaining,
+    shouldResetAfter: reset,
+  };
+}