make seed phrase optional

src/lib/utils.ts

@@ -1,6 +1,79 @@
 import { clsx, type ClassValue } from "clsx"
 import { twMerge } from "tailwind-merge"
+import { mnemonicToAccount } from 'viem/accounts';
 
 export function cn(...inputs: ClassValue[]) {
   return twMerge(clsx(inputs))
 }
+
+export function getSecretEnvVars() {
+  const seedPhrase = process.env.SEED_PHRASE;
+  const fid = process.env.FID;
+  
+  if (!seedPhrase || !fid) {
+    return null;
+  }
+
+  return { seedPhrase, fid };
+}
+
+export async function generateFarcasterMetadata() {
+  const appUrl = process.env.NEXT_PUBLIC_URL;
+  if (!appUrl) {
+    throw new Error('NEXT_PUBLIC_URL not configured');
+  }
+
+  // Get the domain from the URL (without https:// prefix)
+  const domain = new URL(appUrl).hostname;
+  console.log('Using domain for manifest:', domain);
+
+  const secretEnvVars = getSecretEnvVars();
+  if (!secretEnvVars) {
+    console.warn('No seed phrase or FID found in environment variables -- generating unsigned metadata');
+  }
+
+  let accountAssociation;
+  if (secretEnvVars) {
+    // Generate account from seed phrase
+    const account = mnemonicToAccount(secretEnvVars.seedPhrase);
+    const custodyAddress = account.address;
+
+    const header = {
+      fid: parseInt(secretEnvVars.fid),
+      type: 'custody',
+      key: custodyAddress,
+    };
+    const encodedHeader = Buffer.from(JSON.stringify(header), 'utf-8').toString('base64');
+
+    const payload = {
+      domain
+    };
+    const encodedPayload = Buffer.from(JSON.stringify(payload), 'utf-8').toString('base64url');
+
+    const signature = await account.signMessage({ 
+      message: `${encodedHeader}.${encodedPayload}`
+    });
+    const encodedSignature = Buffer.from(signature, 'utf-8').toString('base64url');
+
+    accountAssociation = {
+      header: encodedHeader,
+      payload: encodedPayload,
+      signature: encodedSignature
+    };
+  }
+
+  return {
+    accountAssociation,
+    frame: {
+      version: "1",
+      name: process.env.NEXT_PUBLIC_FRAME_NAME || "Frames v2 Demo",
+      iconUrl: `${appUrl}/icon.png`,
+      homeUrl: appUrl,
+      imageUrl: `${appUrl}/opengraph-image`,
+      buttonTitle: process.env.NEXT_PUBLIC_FRAME_BUTTON_TEXT || "Launch Frame",
+      splashImageUrl: process.env.NEXT_PUBLIC_FRAME_SPLASH_IMAGE_URL || `${appUrl}/splash.png`,
+      splashBackgroundColor: "#f7f7f7",
+      webhookUrl: `${appUrl}/api/webhook`,
+    },
+  };
+}