feat(ProgressiveBilling): Add progressive billing invoice relation to…

… credit (#2440)

## Context

AI companies want their users to pay before the end of a period if usage
skyrockets. The problem being that self-serve companies can overuse
their API without paying, triggering lots of costs on their side.

## Description

This PR adds the `progressive_billing_invoice_id` foreign key column to
the `credits` table. It will allow us to take a progressive billing
invoice into account when generating a subscription invoice

app/models/credit.rb

@@ -6,6 +6,7 @@ class Credit < ApplicationRecord
   belongs_to :invoice
   belongs_to :applied_coupon, optional: true
   belongs_to :credit_note, optional: true
+  belongs_to :progressive_billing_invoice, class_name: 'Invoice', optional: true
 
   has_one :coupon, -> { with_discarded }, through: :applied_coupon
 
@@ -18,25 +19,32 @@ class Credit < ApplicationRecord
 
   def item_id
     return coupon&.id if applied_coupon_id
+    return progressive_billing_invoice_id if progressive_billing_invoice_id?
 
     credit_note.id
   end
 
   def item_type
     return 'coupon' if applied_coupon_id?
+    return 'invoice' if progressive_billing_invoice_id?
 
     'credit_note'
   end
 
   def item_code
     return coupon&.code if applied_coupon_id?
+    return progressive_billing_invoice.number if progressive_billing_invoice_id?
 
     credit_note.number
   end
 
   def item_name
     return coupon&.name if applied_coupon_id?
 
+    if progressive_billing_invoice_id?
+      return progressive_billing_invoice.fees.first&.invoice_name
+    end
+
     # TODO: change it depending on invoice template
     credit_note.invoice.number
   end
@@ -62,25 +70,28 @@ def invoice_coupon_display_name
 #
 # Table name: credits
 #
-#  id                :uuid             not null, primary key
-#  amount_cents      :bigint           not null
-#  amount_currency   :string           not null
-#  before_taxes      :boolean          default(FALSE), not null
-#  created_at        :datetime         not null
-#  updated_at        :datetime         not null
-#  applied_coupon_id :uuid
-#  credit_note_id    :uuid
-#  invoice_id        :uuid
+#  id                             :uuid             not null, primary key
+#  amount_cents                   :bigint           not null
+#  amount_currency                :string           not null
+#  before_taxes                   :boolean          default(FALSE), not null
+#  created_at                     :datetime         not null
+#  updated_at                     :datetime         not null
+#  applied_coupon_id              :uuid
+#  credit_note_id                 :uuid
+#  invoice_id                     :uuid
+#  progressive_billing_invoice_id :uuid
 #
 # Indexes
 #
-#  index_credits_on_applied_coupon_id  (applied_coupon_id)
-#  index_credits_on_credit_note_id     (credit_note_id)
-#  index_credits_on_invoice_id         (invoice_id)
+#  index_credits_on_applied_coupon_id               (applied_coupon_id)
+#  index_credits_on_credit_note_id                  (credit_note_id)
+#  index_credits_on_invoice_id                      (invoice_id)
+#  index_credits_on_progressive_billing_invoice_id  (progressive_billing_invoice_id)
 #
 # Foreign Keys
 #
 #  fk_rails_...  (applied_coupon_id => applied_coupons.id)
 #  fk_rails_...  (credit_note_id => credit_notes.id)
 #  fk_rails_...  (invoice_id => invoices.id)
+#  fk_rails_...  (progressive_billing_invoice_id => invoices.id)
 #

app/models/invoice.rb

@@ -26,6 +26,7 @@ class Invoice < ApplicationRecord
   has_many :plans, through: :subscriptions
   has_many :metadata, class_name: 'Metadata::InvoiceMetadata', dependent: :destroy
   has_many :credit_notes
+  has_many :progressive_billing_credits, class_name: 'Credit', foreign_key: :progressive_billing_invoice_id
 
   has_many :applied_taxes, class_name: 'Invoice::AppliedTax', dependent: :destroy
   has_many :taxes, through: :applied_taxes

db/migrate/20240820090312_attach_progressive_billing_invoices_to_credits.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class AttachProgressiveBillingInvoicesToCredits < ActiveRecord::Migration[7.1]
+  def change
+    add_column :credits, :progressive_billing_invoice_id, :uuid
+    add_foreign_key :credits, :invoices, column: :progressive_billing_invoice_id
+    add_index :credits, :progressive_billing_invoice_id
+  end
+end

spec/factories/credits.rb

@@ -16,4 +16,12 @@
     amount_cents { 200 }
     amount_currency { 'EUR' }
   end
+
+  factory :progressive_billing_invoice_credit, class: 'Credit' do
+    invoice
+    progressive_billing_invoice factory: :invoice
+
+    amount_cents { 200 }
+    amount_currency { 'EUR' }
+  end
 end

spec/models/credit_spec.rb

@@ -3,6 +3,15 @@
 require 'rails_helper'
 
 RSpec.describe Credit, type: :model do
+  subject(:credit) { create(:credit) }
+
+  describe 'associations' do
+    it { is_expected.to belong_to(:invoice) }
+    it { is_expected.to belong_to(:applied_coupon).optional }
+    it { is_expected.to belong_to(:credit_note).optional }
+    it { is_expected.to belong_to(:progressive_billing_invoice).optional }
+  end
+
   describe 'invoice item' do
     context 'when credit is a coupon' do
       subject(:credit) { create(:credit, applied_coupon:) }
@@ -63,5 +72,29 @@
         end
       end
     end
+
+    context 'when credit is a progressive billing invoice' do
+      subject(:credit) { create(:progressive_billing_invoice_credit, progressive_billing_invoice:) }
+
+      let(:progressive_billing_invoice) { create(:invoice, invoice_type: :progressive_billing) }
+      let(:progressive_billing_fee) do
+        create(
+          :fee,
+          invoice: progressive_billing_invoice,
+          fee_type: :progressive_billing
+        )
+      end
+
+      before { progressive_billing_fee }
+
+      it 'returns invoice details', aggregate_failures: true do
+        aggregate_failures do
+          expect(credit.item_id).to eq(progressive_billing_invoice.id)
+          expect(credit.item_type).to eq('invoice')
+          expect(credit.item_code).to eq(progressive_billing_invoice.number)
+          expect(credit.item_name).to eq(progressive_billing_fee.invoice_name)
+        end
+      end
+    end
   end
 end

spec/models/invoice_spec.rb

@@ -14,6 +14,8 @@
   it { is_expected.to have_many(:payment_requests) }
   it { is_expected.to belong_to(:payable_group).optional }
 
+  it { is_expected.to have_many(:progressive_billing_credits) }
+
   it 'has fixed status mapping' do
     expect(described_class::VISIBLE_STATUS).to match(draft: 0, finalized: 1, voided: 2, failed: 4)
     expect(described_class::INVISIBLE_STATUS).to match(generating: 3, open: 5)