chore: import upstream snapshot with attribution

api/src/routes/helpers/auth-helpers.ts

@@ -0,0 +1,76 @@
+import { FastifyInstance } from 'fastify';
+import { createUserInput } from '../../utils/create-user.js';
+import { assignVariantBucket } from '../../utils/drip-campaign.js';
+
+/**
+ * Finds an existing user with the given email or creates a new user if none exists.
+ * @param fastify - The Fastify instance.
+ * @param email - The email of the user.
+ * @returns The existing or newly created user.
+ */
+export const findOrCreateUser = async (
+  fastify: FastifyInstance,
+  email: string
+): Promise<{ id: string; acceptedPrivacyTerms: boolean }> => {
+  // TODO: handle the case where there are multiple users with the same email.
+  // e.g. use findMany and throw an error if more than one is found.
+  const existingUser = await fastify.prisma.user.findMany({
+    where: { email },
+    select: { id: true, acceptedPrivacyTerms: true }
+  });
+  if (existingUser.length > 1) {
+    const userIds = existingUser.map(user => user.id);
+    fastify.log.error(
+      { audit: true, userIds, email },
+      'Multiple user records found'
+    );
+    fastify.Sentry?.captureException(
+      new Error('Multiple user records found for: ' + userIds.join(', '))
+    );
+    fastify.Sentry?.metrics?.count('user.duplicate_email_detected', 1);
+  }
+
+  if (existingUser[0]) {
+    return existingUser[0];
+  }
+
+  // Create new user
+  const newUser = await fastify.prisma.user.create({
+    data: createUserInput(email),
+    select: { id: true, acceptedPrivacyTerms: true }
+  });
+
+  fastify.Sentry?.metrics?.count('user.created', 1);
+
+  // Create drip campaign record if feature flag is enabled
+  if (fastify.gb.isOn('drip-campaign')) {
+    try {
+      const variant = assignVariantBucket(newUser.id);
+      await fastify.prisma.dripCampaign.create({
+        data: {
+          userId: newUser.id,
+          email,
+          variant
+        }
+      });
+      fastify.log.info(
+        { userId: newUser.id, variant },
+        'Drip campaign record created for user'
+      );
+      fastify.Sentry?.metrics?.count('growthbook.signup_flag_evaluated', 1, {
+        attributes: { flag: 'drip-campaign', result: 'success' }
+      });
+    } catch (err) {
+      fastify.Sentry?.captureException(err);
+      fastify.log.error(
+        { err, userId: newUser.id },
+        'Failed to create drip campaign record for user'
+      );
+      fastify.Sentry?.metrics?.count('growthbook.signup_flag_evaluated', 1, {
+        attributes: { flag: 'drip-campaign', result: 'failed' }
+      });
+    }
+  }
+
+  return newUser;
+};