Make payments payer→person/organization migration reversible

db/migrate/20260530000000_change_payments_payer_to_person_organization.rb

@@ -1,11 +1,28 @@
 class ChangePaymentsPayerToPersonOrganization < ActiveRecord::Migration[8.1]
-  def change
-    remove_index :payments, name: "index_payments_on_payer"
-    remove_index :payments, name: "index_payments_on_payer_type_and_payer_id"
+  def up
+    remove_index :payments, name: "index_payments_on_payer", if_exists: true
+    remove_index :payments, name: "index_payments_on_payer_type_and_payer_id", if_exists: true
 
-    remove_column :payments, :payer_id
+    remove_column :payments, :payer_id, if_exists: true
 
-    add_reference :payments, :person, foreign_key: true
-    add_reference :payments, :organization, type: :integer, foreign_key: true
+    unless column_exists?(:payments, :person_id)
+      add_column :payments, :person_id, :bigint
+    end
+    add_index :payments, :person_id, if_not_exists: true
+    add_foreign_key :payments, :people, column: :person_id unless foreign_key_exists?(:payments, :people, column: :person_id)
+    unless column_exists?(:payments, :organization_id)
+      add_column :payments, :organization_id, :integer
+    end
+    add_index :payments, :organization_id, if_not_exists: true
+    add_foreign_key :payments, :organizations, column: :organization_id unless foreign_key_exists?(:payments, :organizations, column: :organization_id)
+  end
+
+  def down
+    remove_reference :payments, :organization, foreign_key: true, if_exists: true
+    remove_reference :payments, :person, foreign_key: true, if_exists: true
+
+    add_column :payments, :payer_id, :bigint unless column_exists?(:payments, :payer_id)
+    add_index :payments, [ :payer_type, :payer_id ], name: "index_payments_on_payer", if_not_exists: true
+    add_index :payments, [ :payer_type, :payer_id ], name: "index_payments_on_payer_type_and_payer_id", if_not_exists: true
   end
 end