fix: inline EventHelper concern into Event model

app/models/event.rb

@@ -2,7 +2,6 @@ class Event < ApplicationRecord
   include DateTimeConcerns
   include Listable
   include Invitable
-  include EventHelper
 
   attr_accessor :local_date, :local_time, :local_end_time
 
@@ -102,4 +101,26 @@ def fetch_duplicated_sponsors
     ids = sponsorships.reject(&:marked_for_destruction?).map(&:sponsor_id)
     ids.select { |e| ids.count(e) > 1 }
   end
+
+  def venue_or_remote_must_be_present
+    if !virtual && !venue
+      errors.add(:venue, 'must be set, or event must be marked as virtual')
+    end
+  end
+
+  def sponsors_uniqueness
+    errors.add(:sponsors, :duplicated_sponsor) unless (sponsors.map(&:id) & duplicated_sponsors).empty?
+  end
+
+  def bronze_sponsors_uniqueness
+    errors.add(:bronze_sponsors, :duplicated_sponsor) unless (bronze_sponsors.map(&:id) & duplicated_sponsors).empty?
+  end
+
+  def silver_sponsors_uniqueness
+    errors.add(:silver_sponsors, :duplicated_sponsor) unless (silver_sponsors.map(&:id) & duplicated_sponsors).empty?
+  end
+
+  def gold_sponsors_uniqueness
+    errors.add(:gold_sponsors, :duplicated_sponsor) unless (gold_sponsors.map(&:id) & duplicated_sponsors).empty?
+  end
 end