Add Optional 2FA Support (#61)

* Add TOTP MFA Support

* Add Passkey MFA Support

It's not impossible I missed some minor cleanup, but most things make sense and there isn't a lot of obvious duplication anymore.

---------

Co-authored-by: Bruno Bernardino <me@brunobernardino.com>

routes/api/auth/multi-factor/passkey/setup-complete.ts

@@ -0,0 +1,102 @@
+import { Handlers } from 'fresh/server.ts';
+import { isoBase64URL } from '@simplewebauthn/server/helpers';
+import { RegistrationResponseJSON } from '@simplewebauthn/server';
+
+import { FreshContextState } from '/lib/types.ts';
+import { PasskeyModel } from '/lib/models/multi-factor-auth/passkey.ts';
+import { UserModel } from '/lib/models/user.ts';
+import { AppConfig } from '/lib/config.ts';
+
+export interface RequestBody {
+  methodId: string;
+  challenge: string;
+  registrationResponse: RegistrationResponseJSON;
+}
+
+export interface ResponseBody {
+  success: boolean;
+  error?: string;
+}
+
+export const handler: Handlers<unknown, FreshContextState> = {
+  async POST(request, context) {
+    if (!context.state.user) {
+      return new Response('Unauthorized', { status: 401 });
+    }
+
+    const isMultiFactorAuthEnabled = await AppConfig.isMultiFactorAuthEnabled();
+
+    if (!isMultiFactorAuthEnabled) {
+      const responseBody: ResponseBody = {
+        success: false,
+        error: 'Passwordless passkey login requires multi-factor authentication to be enabled.',
+      };
+
+      return new Response(JSON.stringify(responseBody), { status: 403 });
+    }
+
+    const { user } = context.state;
+
+    const body = await request.clone().json() as RequestBody;
+    const { methodId, challenge, registrationResponse } = body;
+
+    if (!methodId || !challenge || !registrationResponse) {
+      const responseBody: ResponseBody = {
+        success: false,
+        error: 'Method ID, challenge, and registration response are required',
+      };
+
+      return new Response(JSON.stringify(responseBody), { status: 400 });
+    }
+
+    const config = await AppConfig.getConfig();
+    const expectedOrigin = config.auth.baseUrl;
+    const expectedRPID = new URL(config.auth.baseUrl).hostname;
+
+    const verification = await PasskeyModel.verifyRegistration(
+      registrationResponse,
+      challenge,
+      expectedOrigin,
+      expectedRPID,
+    );
+
+    if (!verification.verified || !verification.registrationInfo) {
+      const responseBody: ResponseBody = {
+        success: false,
+        error: 'Passkey registration verification failed',
+      };
+
+      return new Response(JSON.stringify(responseBody), { status: 400 });
+    }
+
+    const { registrationInfo } = verification;
+    const credentialID = registrationInfo.credential.id;
+    const credentialPublicKey = isoBase64URL.fromBuffer(registrationInfo.credential.publicKey);
+
+    const method = PasskeyModel.createMethod(
+      methodId,
+      'Passkey',
+      credentialID,
+      credentialPublicKey,
+      registrationInfo.credential.counter,
+      registrationInfo.credentialDeviceType,
+      registrationInfo.credentialBackedUp,
+      // @ts-expect-error SimpleWebAuthn supports a few more transports, and that's OK
+      registrationResponse.response?.transports || [],
+    );
+
+    if (!user.extra.multi_factor_auth_methods) {
+      user.extra.multi_factor_auth_methods = [];
+    }
+
+    user.extra.multi_factor_auth_methods.push(method);
+
+    await UserModel.update(user);
+
+    const responseBody: ResponseBody = {
+      success: true,
+    };
+
+    return new Response(JSON.stringify(responseBody));
+  },
+};