feat(dunning): reset customer dunning campaign last attempt data on t…

…hreshold changes (#2861)

## Roadmap

👉 https://getlago.canny.io/feature-requests/p/set-up-payment-retry-logic

👉
https://getlago.canny.io/feature-requests/p/send-reminders-for-overdue-invoices

 ## Context

We want to automate dunning process so that our users don't have to look
at each customer to maximize their chances of being paid retrying
payments of overdue balances and sending email reminders.

We are extending dunning campaigns management to edit and delete
campaigns.

 ## Description

When a dunning campaign threshold changes, it resets customers
last_dunning_campaign_attempt fields with the updated campaign
applicable (through direct association or falling back to it through the
organization default) when the thresholds does not match anymore
(currency and/or amount_cents changed or deletion of the threshold).

app/models/dunning_campaign_threshold.rb

@@ -10,7 +10,7 @@ class DunningCampaignThreshold < ApplicationRecord
 
   validates :amount_cents, numericality: {greater_than_or_equal_to: 0}
   validates :currency, inclusion: {in: currency_list}
-  validates :currency, uniqueness: {scope: :dunning_campaign_id}, unless: :deleted_at
+  validates :currency, uniqueness: {scope: :dunning_campaign_id, conditions: -> { where(deleted_at: nil) }}
 
   default_scope -> { kept }
 end

app/services/dunning_campaigns/update_service.rb

@@ -15,22 +15,9 @@ def call
       return result.not_found_failure!(resource: "dunning_campaign") unless dunning_campaign
 
       ActiveRecord::Base.transaction do
-        dunning_campaign.name = params[:name] if params.key?(:name)
-        dunning_campaign.code = params[:code] if params.key?(:code)
-        dunning_campaign.description = params[:description] if params.key?(:description)
-        dunning_campaign.days_between_attempts = params[:days_between_attempts] if params.key?(:days_between_attempts)
-        dunning_campaign.max_attempts = params[:max_attempts] if params.key?(:max_attempts)
-
+        dunning_campaign.assign_attributes(permitted_attributes)
         handle_thresholds if params.key?(:thresholds)
-
-        unless params[:applied_to_organization].nil?
-          organization.dunning_campaigns.applied_to_organization
-            .update_all(applied_to_organization: false) # rubocop:disable Rails/SkipsModelValidations
-
-          organization.reset_customers_last_dunning_campaign_attempt
-
-          dunning_campaign.applied_to_organization = params[:applied_to_organization]
-        end
+        handle_applied_to_organization_update if params.key?(:applied_to_organization)
 
         dunning_campaign.save!
       end
@@ -45,21 +32,79 @@ def call
 
     attr_reader :dunning_campaign, :organization, :params
 
+    def permitted_attributes
+      params.slice(:name, :code, :description, :days_between_attempts, :max_attempts)
+    end
+
     def handle_thresholds
+      thresholds_updated = false
+
       input_threshold_ids = params[:thresholds].map { |t| t[:id] }.compact
 
       # Delete thresholds not included in the payload
-      dunning_campaign.thresholds.where.not(id: input_threshold_ids).discard_all
+      discarded_thresholds = dunning_campaign
+        .thresholds
+        .where.not(id: input_threshold_ids)
+        .discard_all
+
+      thresholds_updated = discarded_thresholds.present?
 
       # Update or create new thresholds from the input
       params[:thresholds].each do |threshold_input|
-        dunning_campaign.thresholds.find_or_initialize_by(
+        threshold = dunning_campaign.thresholds.find_or_initialize_by(
           id: threshold_input[:id]
-        ).update!(
-          amount_cents: threshold_input[:amount_cents],
-          currency: threshold_input[:currency]
         )
+
+        threshold.assign_attributes(threshold_input.to_h.slice(:amount_cents, :currency))
+
+        thresholds_updated ||= threshold.changed? && threshold.persisted?
+        threshold.save!
       end
+
+      reset_customers_if_no_threshold_match if thresholds_updated
+    end
+
+    def reset_customers_if_no_threshold_match
+      customers_applied_campaign = organization
+        .customers
+        .with_dunning_campaign_not_completed
+        .where(applied_dunning_campaign: dunning_campaign)
+
+      customers_fallback_campaign = organization
+        .customers
+        .falling_back_to_default_dunning_campaign
+        .with_dunning_campaign_not_completed
+
+      customers_to_reset = customers_applied_campaign.or(customers_fallback_campaign)
+
+      customers_to_reset
+        .includes(:invoices)
+        .where(invoices: {payment_overdue: true}).find_each do |customer|
+          threshold_matches = dunning_campaign.thresholds.any? do |threshold|
+            threshold.currency == customer.currency &&
+              customer.overdue_balance_cents >= threshold.amount_cents
+          end
+
+          unless threshold_matches
+            customer.update!(
+              last_dunning_campaign_attempt: 0,
+              last_dunning_campaign_attempt_at: nil
+            )
+          end
+        end
+    end
+
+    def handle_applied_to_organization_update
+      dunning_campaign.applied_to_organization = params[:applied_to_organization]
+
+      return unless dunning_campaign.applied_to_organization_changed?
+
+      organization
+        .dunning_campaigns
+        .applied_to_organization
+        .update_all(applied_to_organization: false) # rubocop:disable Rails/SkipsModelValidations
+
+      organization.reset_customers_last_dunning_campaign_attempt
     end
   end
 end

spec/models/dunning_campaign_threshold_spec.rb

@@ -18,15 +18,14 @@
     let(:dunning_campaign) { create(:dunning_campaign) }
 
     it "validates uniqueness of currency scoped to dunning_campaign_id excluding deleted records" do
-      create(:dunning_campaign_threshold, currency:, dunning_campaign:)
+      existing_record = create(:dunning_campaign_threshold, currency:, dunning_campaign:)
       new_record = build(:dunning_campaign_threshold, currency:, dunning_campaign:)
 
       expect(new_record).not_to be_valid
       expect(new_record.errors[:currency]).to include("value_already_exist")
 
-      # Records with deleted_at set should not conflict
-      deleted_record = create(:dunning_campaign_threshold, :deleted, currency:, dunning_campaign:)
-      expect(deleted_record).to be_valid
+      existing_record.discard
+      expect(new_record).to be_valid
     end
   end