Refactor line item total calculations

This updates Spree::OrderUpdater to use the new ItemTotal class,
avoiding duplicating all of that logic.

Co-authored-by: Chris Todorov <[email protected]>
Co-authored-by: Adam Mueller <[email protected]>
Co-authored-by: Alistair Norman <[email protected]>
Co-authored-by: benjamin wil <[email protected]>
Co-authored-by: Harmony Bouvier <[email protected]>
Co-authored-by: Sofia Besenski <[email protected]>

core/app/models/spree/order_updater.rb

@@ -113,7 +113,7 @@ def recalculate_adjustments
       # It also fits the criteria for sales tax as outlined here:
       # http://www.boe.ca.gov/formspubs/pub113/
       update_promotions
-      update_taxes
+      update_tax_adjustments
       update_item_totals
     end
 
@@ -198,24 +198,8 @@ def update_promotions
       Spree::Config.promotions.order_adjuster_class.new(order).call
     end
 
-    def update_taxes
+    def update_tax_adjustments
       Spree::Config.tax_adjuster_class.new(order).adjust!
-
-      [*line_items, *shipments].each do |item|
-        tax_adjustments = item.adjustments.select { |adjustment|
-          adjustment.tax? && !adjustment.marked_for_destruction?
-        }
-
-        # Tax adjustments come in not one but *two* exciting flavours:
-        # Included & additional
-
-        # Included tax adjustments are those which are included in the price.
-        # These ones should not affect the eventual total price.
-        #
-        # Additional tax adjustments are the opposite, affecting the final total.
-        item.included_tax_total   = tax_adjustments.select(&:included?).sum(&:amount)
-        item.additional_tax_total = tax_adjustments.reject(&:included?).sum(&:amount)
-      end
     end
 
     def update_cancellations
@@ -224,21 +208,17 @@ def update_cancellations
 
     def update_item_totals
       [*line_items, *shipments].each do |item|
-        # The cancellation_total isn't persisted anywhere but is included in
-        # the adjustment_total
-        item.adjustment_total = item.adjustments.
-          reject { |adjustment| adjustment.included? || adjustment.marked_for_destruction? }.
-          sum(&:amount)
-
-        if item.changed?
-          item.update_columns(
-            promo_total:          item.promo_total,
-            included_tax_total:   item.included_tax_total,
-            additional_tax_total: item.additional_tax_total,
-            adjustment_total:     item.adjustment_total,
-            updated_at:           Time.current,
-          )
-        end
+        Spree::ItemTotal.new(item).recalculate!
+
+        next unless item.changed?
+
+        item.update_columns(
+          promo_total:          item.promo_total,
+          included_tax_total:   item.included_tax_total,
+          additional_tax_total: item.additional_tax_total,
+          adjustment_total:     item.adjustment_total,
+          updated_at:           Time.current,
+        )
       end
     end
   end