Feat: anrok <> credit_notes model changes (#2558)

We need to adjust credit_note and credit_note::applied_tax to reflect
the changes in processing taxes:
- applied_tax might not belong to a stored in lago tax, so tax_id
becomes optional,
- during reporting we might receive some errors, so credit_note can have
many :error_details

app/models/credit_note.rb

@@ -21,6 +21,7 @@ class CreditNote < ApplicationRecord
   has_many :applied_taxes, class_name: 'CreditNote::AppliedTax', dependent: :destroy
   has_many :taxes, through: :applied_taxes
   has_many :integration_resources, as: :syncable
+  has_many :error_details, as: :owner, dependent: :destroy
 
   has_one_attached :file
 

app/models/credit_note/applied_tax.rb

@@ -7,7 +7,7 @@ class AppliedTax < ApplicationRecord
     include PaperTrailTraceable
 
     belongs_to :credit_note
-    belongs_to :tax
+    belongs_to :tax, optional: true
 
     monetize :amount_cents
     monetize :base_amount_cents, with_model_currency: :amount_currency
@@ -29,13 +29,14 @@ class AppliedTax < ApplicationRecord
 #  created_at        :datetime         not null
 #  updated_at        :datetime         not null
 #  credit_note_id    :uuid             not null
-#  tax_id            :uuid             not null
+#  tax_id            :uuid
 #
 # Indexes
 #
-#  index_credit_notes_taxes_on_credit_note_id             (credit_note_id)
-#  index_credit_notes_taxes_on_credit_note_id_and_tax_id  (credit_note_id,tax_id) UNIQUE
-#  index_credit_notes_taxes_on_tax_id                     (tax_id)
+#  index_credit_notes_taxes_on_credit_note_id               (credit_note_id)
+#  index_credit_notes_taxes_on_credit_note_id_and_tax_code  (credit_note_id,tax_code) UNIQUE
+#  index_credit_notes_taxes_on_tax_code                     (tax_code)
+#  index_credit_notes_taxes_on_tax_id                       (tax_id)
 #
 # Foreign Keys
 #

db/migrate/20240910093646_change_tax_id_null_on_credit_note_applied_taxes.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class ChangeTaxIdNullOnCreditNoteAppliedTaxes < ActiveRecord::Migration[7.1]
+  def change
+    change_column_null :credit_notes_taxes, :tax_id, true
+  end
+end

db/migrate/20240910111203_update_indexes_for_credit_notes_taxes.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class UpdateIndexesForCreditNotesTaxes < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  def change
+    remove_index :credit_notes_taxes, %i[credit_note_id tax_id], unique: true, algorithm: :concurrently
+
+    add_index :credit_notes_taxes, :tax_code, algorithm: :concurrently
+    add_index :credit_notes_taxes, %i[credit_note_id tax_code], unique: true, algorithm: :concurrently
+  end
+end

spec/models/credit_note/applied_tax_spec.rb

@@ -5,5 +5,10 @@
 RSpec.describe CreditNote::AppliedTax, type: :model do
   subject(:applied_tax) { create(:credit_note_applied_tax) }
 
+  describe 'associations' do
+    it { is_expected.to belong_to(:credit_note) }
+    it { is_expected.to belong_to(:tax).optional }
+  end
+
   it_behaves_like 'paper_trail traceable'
 end

spec/models/credit_note_spec.rb

@@ -8,6 +8,7 @@
   it_behaves_like 'paper_trail traceable'
 
   it { is_expected.to have_many(:integration_resources) }
+  it { is_expected.to have_many(:error_details) }
 
   describe 'sequential_id' do
     let(:invoice) { create(:invoice) }