Add notification savings + webhook validation

src/lib/notifs.ts

@@ -0,0 +1,65 @@
+import {
+  SendNotificationRequest,
+  sendNotificationResponseSchema,
+} from "@farcaster/frame-sdk";
+import { getUserNotificationDetails } from "~/lib/kv";
+
+const appUrl = process.env.NEXT_PUBLIC_URL || "";
+
+type SendFrameNotificationResult =
+  | {
+      state: "error";
+      error: unknown;
+    }
+  | { state: "no_token" }
+  | { state: "rate_limit" }
+  | { state: "success" };
+
+export async function sendFrameNotification({
+  fid,
+  title,
+  body,
+}: {
+  fid: number;
+  title: string;
+  body: string;
+}): Promise<SendFrameNotificationResult> {
+  const notificationDetails = await getUserNotificationDetails(fid);
+  if (!notificationDetails) {
+    return { state: "no_token" };
+  }
+
+  const response = await fetch(notificationDetails.url, {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({
+      notificationId: crypto.randomUUID(),
+      title,
+      body,
+      targetUrl: appUrl,
+      tokens: [notificationDetails.token],
+    } satisfies SendNotificationRequest),
+  });
+
+  const responseJson = await response.json();
+
+  if (response.status === 200) {
+    const responseBody = sendNotificationResponseSchema.safeParse(responseJson);
+    if (responseBody.success === false) {
+      // Malformed response
+      return { state: "error", error: responseBody.error.errors };
+    }
+
+    if (responseBody.data.result.rateLimitedTokens.length) {
+      // Rate limited
+      return { state: "rate_limit" };
+    }
+
+    return { state: "success" };
+  } else {
+    // Error response
+    return { state: "error", error: responseJson };
+  }
+}