fix: show correct authentication action for account required (#1191)

## Description

When using account required auth for a given document this change now
shows the sign up or sign in button depending on if an account actually
exists within
Documenso.

This change should reduce friction and confusion when a recipient has
been invited to a document.

## Related Issue

<!--- If this pull request is related to a specific issue, reference it
here using #issue_number. -->
<!--- For example, "Fixes #123" or "Addresses #456". -->

## Changes Made

- Updated the ssr for the signing page to fetch whether a user account
exists when document auth is required
- Pass the user exists flag to the document auth required page

## Testing Performed

- Created and sent a document to a user with an account and one without an account in both a logged in and logged out state and confirmed that the dialogs are displayed as expected.

apps/web/src/app/(signing)/sign/[token]/page.tsx

@@ -10,6 +10,7 @@ import { getCompletedFieldsForToken } from '@documenso/lib/server-only/field/get
 import { getFieldsForToken } from '@documenso/lib/server-only/field/get-fields-for-token';
 import { getRecipientByToken } from '@documenso/lib/server-only/recipient/get-recipient-by-token';
 import { getRecipientSignatures } from '@documenso/lib/server-only/recipient/get-recipient-signatures';
+import { getUserByEmail } from '@documenso/lib/server-only/user/get-user-by-email';
 import { symmetricDecrypt } from '@documenso/lib/universal/crypto';
 import { extractNextHeaderRequestMetadata } from '@documenso/lib/universal/extract-request-metadata';
 import { extractDocumentAuthMethods } from '@documenso/lib/utils/document-auth';
@@ -70,8 +71,14 @@ export default async function SigningPage({ params: { token } }: SigningPageProp
     userId: user?.id,
   });
 
+  let recipientHasAccount: boolean | null = null;
+
   if (!isDocumentAccessValid) {
-    return <SigningAuthPageView email={recipient.email} />;
+    recipientHasAccount = await getUserByEmail({ email: recipient?.email })
+      .then((user) => !!user)
+      .catch(() => false);
+
+    return <SigningAuthPageView email={recipient.email} emailHasAccount={!!recipientHasAccount} />;
   }
 
   await viewedDocument({

apps/web/src/app/(signing)/sign/[token]/signing-auth-page.tsx

@@ -11,9 +11,10 @@ import { useToast } from '@documenso/ui/primitives/use-toast';
 
 export type SigningAuthPageViewProps = {
   email: string;
+  emailHasAccount?: boolean;
 };
 
-export const SigningAuthPageView = ({ email }: SigningAuthPageViewProps) => {
+export const SigningAuthPageView = ({ email, emailHasAccount }: SigningAuthPageViewProps) => {
   const { toast } = useToast();
 
   const [isSigningOut, setIsSigningOut] = useState(false);
@@ -30,7 +31,9 @@ export const SigningAuthPageView = ({ email }: SigningAuthPageViewProps) => {
       });
 
       await signOut({
-        callbackUrl: `/signin?email=${encodeURIComponent(encryptedEmail)}`,
+        callbackUrl: emailHasAccount
+          ? `/signin?email=${encodeURIComponent(encryptedEmail)}`
+          : `/signup?email=${encodeURIComponent(encryptedEmail)}`,
       });
     } catch {
       toast({
@@ -59,7 +62,7 @@ export const SigningAuthPageView = ({ email }: SigningAuthPageViewProps) => {
           onClick={async () => handleChangeAccount(email)}
           loading={isSigningOut}
         >
-          Login
+          {emailHasAccount ? 'Login' : 'Sign up'}
         </Button>
       </div>
     </div>