Use new NestedClassSet for configuring calculators

app/models/solidus_friendly_promotions/actions/adjust_line_item.rb

@@ -7,10 +7,6 @@ def can_discount?(object)
         object.is_a? Spree::LineItem
       end
 
-      def available_calculators
-        SolidusFriendlyPromotions.config.line_item_discount_calculators
-      end
-
       def level
         :line_item
       end

app/models/solidus_friendly_promotions/actions/adjust_shipment.rb

@@ -7,10 +7,6 @@ def can_discount?(object)
         object.is_a?(Spree::Shipment) || object.is_a?(Spree::ShippingRate)
       end
 
-      def available_calculators
-        SolidusFriendlyPromotions.config.shipment_discount_calculators
-      end
-
       def level
         :shipment
       end

app/models/solidus_friendly_promotions/promotion_action.rb

@@ -67,7 +67,7 @@ def relevant_rules
     end
 
     def available_calculators
-      raise NotImplementedError
+      SolidusFriendlyPromotions.config.promotion_calculators[self.class] || (raise NotImplementedError)
     end
   end
 end

lib/generators/solidus_friendly_promotions/install/templates/initializer.rb

@@ -63,21 +63,27 @@
   # How many promotions should be displayed on the index page in the admin.
   config.promotions_per_page = 25
 
-  config.shipment_discount_calculators = [
-    "SolidusFriendlyPromotions::Calculators::FlatRate",
-    "SolidusFriendlyPromotions::Calculators::FlexiRate",
-    "SolidusFriendlyPromotions::Calculators::Percent",
-    "SolidusFriendlyPromotions::Calculators::TieredFlatRate",
-    "SolidusFriendlyPromotions::Calculators::TieredPercent"
-  ]
-  config.line_item_discount_calculators = [
-    "SolidusFriendlyPromotions::Calculators::DistributedAmount",
-    "SolidusFriendlyPromotions::Calculators::FlatRate",
-    "SolidusFriendlyPromotions::Calculators::FlexiRate",
-    "SolidusFriendlyPromotions::Calculators::Percent",
-    "SolidusFriendlyPromotions::Calculators::TieredFlatRate",
-    "SolidusFriendlyPromotions::Calculators::TieredPercent"
-  ]
+  config.promotion_calculators = SolidusFriendlyPromotions::NestedClassSet.new(
+    "SolidusFriendlyPromotions::Actions::AdjustShipment" => [
+      "SolidusFriendlyPromotions::Calculators::FlatRate",
+      "SolidusFriendlyPromotions::Calculators::FlexiRate",
+      "SolidusFriendlyPromotions::Calculators::Percent",
+      "SolidusFriendlyPromotions::Calculators::TieredFlatRate",
+      "SolidusFriendlyPromotions::Calculators::TieredPercent"
+    ],
+    "SolidusFriendlyPromotions::Actions::AdjustLineItem" => [
+      "SolidusFriendlyPromotions::Calculators::DistributedAmount",
+      "SolidusFriendlyPromotions::Calculators::FlatRate",
+      "SolidusFriendlyPromotions::Calculators::FlexiRate",
+      "SolidusFriendlyPromotions::Calculators::Percent",
+      "SolidusFriendlyPromotions::Calculators::TieredFlatRate",
+      "SolidusFriendlyPromotions::Calculators::TieredPercent"
+    ],
+    "SolidusFriendlyPromotions::Actions::AdjustLineItemQuantityGroups" => [
+      "SolidusFriendlyPromotions::Calculators::FlatRate",
+      "SolidusFriendlyPromotions::Calculators::Percent"
+    ]
+  )
 
   config.order_rules = [
     "SolidusFriendlyPromotions::Rules::FirstOrder",

lib/solidus_friendly_promotions.rb

@@ -6,6 +6,7 @@
 require "turbo-rails"
 require "importmap-rails"
 require "stimulus-rails"
+require "solidus_friendly_promotions/nested_class_set"
 require "solidus_friendly_promotions/configuration"
 require "solidus_friendly_promotions/version"
 require "solidus_friendly_promotions/engine"

lib/solidus_friendly_promotions/configuration.rb

@@ -5,9 +5,11 @@
 module SolidusFriendlyPromotions
   class Configuration < Spree::Preferences::Configuration
     attr_accessor :sync_order_promotions
+    attr_accessor :promotion_calculators
 
     def initialize
       @sync_order_promotions = true
+      @promotion_calculators = NestedClassSet.new
     end
 
     include Spree::Core::EnvironmentExtension

lib/solidus_friendly_promotions/nested_class_set.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require "spree/core/class_constantizer"
+
+module SolidusFriendlyPromotions
+  class NestedClassSet
+    attr_reader :klass_sets
+
+    def initialize(hash = {})
+      @klass_sets = hash.map do |key, value|
+        [
+          key,
+          Spree::Core::ClassConstantizer::Set.new.tap do |set|
+            value.each { |klass_name| set << klass_name }
+          end
+        ]
+      end.to_h
+    end
+
+    def [](klass)
+      klass_sets[klass.name]
+    end
+  end
+end

spec/lib/solidus_friendly_promotions/configuration_spec.rb

@@ -19,16 +19,10 @@
     end
   end
 
-  describe ".shipment_discount_calculators" do
-    subject { config.shipment_discount_calculators }
+  describe ".promotion_calculators" do
+    subject { config.promotion_calculators }
 
-    it { is_expected.to be_a(Spree::Core::ClassConstantizer::Set) }
-  end
-
-  describe ".line_item_discount_calculators" do
-    subject { config.line_item_discount_calculators }
-
-    it { is_expected.to be_a(Spree::Core::ClassConstantizer::Set) }
+    it { is_expected.to be_a(SolidusFriendlyPromotions::NestedClassSet) }
   end
 
   describe ".order_rules" do