feat(auth): add two-factor authentication support

1 files changed, 27 insertions, 0 deletions

diff --git a/src/lib/auth-helpers.ts b/src/lib/auth-helpers.ts
new file mode 100644
index 0000000..b2d7488
--- /dev/null
+++ b/src/lib/auth-helpers.ts
@@ -0,0 +1,27 @@
+import { authenticator } from "otplib"
+
+interface TwoFactorCheck {
+  twoFactorEnabled?: boolean
+  twoFactorSecret?: string
+}
+
+export function verifyTwoFactor(
+  user: TwoFactorCheck, 
+  code?: string
+): void {
+  if (user.twoFactorEnabled) {
+    // If the user signed up but hasn't set up 2FA yet (secret is missing),
+    // we can either skip 2FA or treat it as disabled.
+    // Here we treat it as disabled if no secret is present.
+    if (user.twoFactorSecret) {
+      if (!code) {
+        throw new Error("2FA_REQUIRED")
+      }
+
+      const isValid = authenticator.check(code, user.twoFactorSecret)
+      if (!isValid) {
+        throw new Error("Invalid 2FA Code")
+      }
+    }
+  }
+}