Merge pull request #81 from friendlycart/allow-updating-goodie-quantity

Allow changing quantity for automatic line items

promotions/app/decorators/models/solidus_friendly_promotions/line_item_decorator.rb

@@ -3,18 +3,24 @@
 module SolidusFriendlyPromotions
   module LineItemDecorator
     def self.prepended(base)
+      base.attr_accessor :quantity_setter
       base.belongs_to :managed_by_order_action, class_name: "SolidusFriendlyPromotions::PromotionAction", optional: true
       base.validate :validate_managed_quantity_same, on: :update
+      base.after_save :reset_quantity_setter
     end
 
     private
 
     def validate_managed_quantity_same
-      if managed_by_order_action && quantity_changed?
+      if managed_by_order_action && quantity_changed? && quantity_setter != managed_by_order_action
         errors.add(:quantity, :cannot_be_changed_for_automated_items)
       end
     end
 
+    def reset_quantity_setter
+      @quantity_setter = nil
+    end
+
     Spree::LineItem.prepend self
     Spree::LineItem.prepend SolidusFriendlyPromotions::DiscountableAmount
   end

promotions/app/models/solidus_friendly_promotions/actions/create_discounted_item.rb

@@ -6,9 +6,11 @@ class CreateDiscountedItem < PromotionAction
       include OrderLevelAction
       preference :variant_id, :integer
       preference :quantity, :integer, default: 1
+      preference :necessary_quantity, :integer, default: 1
 
       def perform(order)
         line_item = find_item(order) || create_item(order)
+        set_quantity(line_item, determine_item_quantity(order))
         line_item.current_discounts << discount(line_item)
       end
 
@@ -24,7 +26,20 @@ def find_item(order)
       end
 
       def create_item(order)
-        order.line_items.create!(quantity: preferred_quantity, variant: variant, managed_by_order_action: self)
+        order.line_items.create!(quantity: determine_item_quantity(order), variant: variant, managed_by_order_action: self)
+      end
+
+      def determine_item_quantity(order)
+        applicable_line_items = promotion.applicable_line_items(order)
+        # Integer division will floor automatically, which is what we want here:
+        # 1 Item, 2 needed: 1 * 1 / 2 => 0
+        # 5 items, 2 preferred, 2 needed: 5 / 2 * 2 => 4
+        applicable_line_items.sum(&:quantity) / preferred_necessary_quantity * preferred_quantity
+      end
+
+      def set_quantity(line_item, quantity)
+        line_item.quantity_setter = self
+        line_item.quantity = quantity
       end
 
       def variant

promotions/app/views/solidus_friendly_promotions/admin/promotion_actions/actions/_create_discounted_item.html.erb

@@ -5,6 +5,10 @@
     <%= form.label :preferred_quantity %>
     <%= form.number_field :preferred_quantity, class: "fullwidth" %>
   </div>
+  <div class="field">
+    <%= form.label :preferred_necessary_quantity %>
+    <%= form.number_field :preferred_necessary_quantity, class: "fullwidth" %>
+  </div>
 <% end %>
 
 <%= render(

promotions/config/locales/en.yml

@@ -203,7 +203,9 @@ en:
       solidus_friendly_promotions/actions/adjust_shipment:
         description: Creates a promotion credit on matching shipments
       solidus_friendly_promotions/actions/create_discounted_item:
-        description: Creates a discounted item
+        description: Creates a discounted item with the quantity the applicable line items.
+        preferred_quantity: Quantity per applicable line item quantity
+        preferred_necessary_quantity: Number of items needed for a discounted item
       solidus_friendly_promotions/rules/first_order:
         description: Must be the customer's first order
       solidus_friendly_promotions/rules/first_repeat_purchase_since:

promotions/spec/models/promotion/integration_spec.rb

@@ -38,6 +38,7 @@
         let(:goodie) { create(:variant, price: 4) }
         let(:action) { SolidusFriendlyPromotions::Actions::CreateDiscountedItem.new(preferred_variant_id: goodie.id, calculator: hundred_percent) }
         let(:hundred_percent) { SolidusFriendlyPromotions::Calculators::Percent.new(preferred_percent: 100) }
+        let(:rule) { SolidusFriendlyPromotions::Rules::Product.new(products: [shirt], preferred_line_item_applicable: true) }
 
         it "creates a new discounted line item" do
           expect(order.adjustments).to be_empty
@@ -48,6 +49,21 @@
           expect(order.line_items.flat_map(&:adjustments).length).to eq(1)
         end
 
+        context "when a second base item is added" do
+          before do
+            order.contents.add(shirt.master)
+          end
+
+          it "creates a new discounted line item" do
+            expect(order.adjustments).to be_empty
+            expect(order.line_items.count).to eq(3)
+            expect(order.total).to eq(59.97)
+            expect(order.item_total).to eq(67.97)
+            expect(order.item_total_before_tax).to eq(59.97)
+            expect(order.line_items.flat_map(&:adjustments).length).to eq(1)
+          end
+        end
+
         context "when the goodie becomes unavailable" do
           before do
             order.contents.remove(shirt.master)