Migrate AnomalyNotification to contributor

* Also, this commit aims to fix the (broken) anomaly notifications.

db/migrate/20230821062816_rename_user_to_contributor_in_anomaly_notifications.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class RenameUserToContributorInAnomalyNotifications < ActiveRecord::Migration[7.0]
+  def change
+    # We need to drop and recreate the index because the name would be too long otherwise.
+    # Renaming is not possible because the index can have two different names.
+
+    change_table :anomaly_notifications do |t|
+      t.remove_index %i[user_type user_id]
+      t.rename :user_id, :contributor_id
+      t.rename :user_type, :contributor_type
+    end
+
+    add_index :anomaly_notifications, %i[contributor_type contributor_id], name: 'index_anomaly_notifications_on_contributor'
+  end
+end

db/migrate/20230821062901_add_foreign_keys_to_anomaly_notifications.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class AddForeignKeysToAnomalyNotifications < ActiveRecord::Migration[7.0]
+  def change
+    up_only do
+      # We cannot add a foreign key to a table that has rows that violate the constraint.
+      AnomalyNotification.where.not(exercise_id: Exercise.all.select(:id)).delete_all
+    end
+
+    change_column_null :anomaly_notifications, :contributor_id, false
+    change_column_null :anomaly_notifications, :contributor_type, false
+
+    change_column_null :anomaly_notifications, :exercise_id, false
+    add_foreign_key :anomaly_notifications, :exercises
+
+    change_column_null :anomaly_notifications, :exercise_collection_id, false
+    add_foreign_key :anomaly_notifications, :exercise_collections
+  end
+
+  class AnomalyNotification < ActiveRecord::Base; end
+  class Exercise < ActiveRecord::Base; end
+  class ExerciseCollection < ActiveRecord::Base; end
+end

db/migrate/20230821063101_convert_reason_to_json_in_anomaly_notifications.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class ConvertReasonToJsonInAnomalyNotifications < ActiveRecord::Migration[7.0]
+  def up
+    AnomalyNotification.where("reason LIKE '%value:%'").each do |anomaly_notification|
+      reason = anomaly_notification.reason
+      reason = reason.gsub('value:', '"value":')
+      reason = reason.gsub(/"(\d+\.\d+)"/) {|_| Regexp.last_match(1) }
+      anomaly_notification.update!(reason:)
+    end
+    change_column :anomaly_notifications, :reason, :jsonb, using: 'reason::jsonb'
+  end
+
+  def down
+    change_column :anomaly_notifications, :reason, :string
+  end
+
+  class AnomalyNotification < ActiveRecord::Base; end
+end