refactor: extract business logic from routes into reusable service modules

server/src/services/notificationPreferencesService.ts

@@ -0,0 +1,40 @@
+import { db } from '../db/database';
+
+export function getPreferences(userId: number) {
+  let prefs = db.prepare('SELECT * FROM notification_preferences WHERE user_id = ?').get(userId);
+  if (!prefs) {
+    db.prepare('INSERT INTO notification_preferences (user_id) VALUES (?)').run(userId);
+    prefs = db.prepare('SELECT * FROM notification_preferences WHERE user_id = ?').get(userId);
+  }
+  return prefs;
+}
+
+export function updatePreferences(
+  userId: number,
+  fields: {
+    notify_trip_invite?: boolean;
+    notify_booking_change?: boolean;
+    notify_trip_reminder?: boolean;
+    notify_webhook?: boolean;
+  }
+) {
+  const existing = db.prepare('SELECT id FROM notification_preferences WHERE user_id = ?').get(userId);
+  if (!existing) {
+    db.prepare('INSERT INTO notification_preferences (user_id) VALUES (?)').run(userId);
+  }
+
+  db.prepare(`UPDATE notification_preferences SET
+    notify_trip_invite = COALESCE(?, notify_trip_invite),
+    notify_booking_change = COALESCE(?, notify_booking_change),
+    notify_trip_reminder = COALESCE(?, notify_trip_reminder),
+    notify_webhook = COALESCE(?, notify_webhook)
+    WHERE user_id = ?`).run(
+    fields.notify_trip_invite !== undefined ? (fields.notify_trip_invite ? 1 : 0) : null,
+    fields.notify_booking_change !== undefined ? (fields.notify_booking_change ? 1 : 0) : null,
+    fields.notify_trip_reminder !== undefined ? (fields.notify_trip_reminder ? 1 : 0) : null,
+    fields.notify_webhook !== undefined ? (fields.notify_webhook ? 1 : 0) : null,
+    userId
+  );
+
+  return db.prepare('SELECT * FROM notification_preferences WHERE user_id = ?').get(userId);
+}