Use DiscountCalculator and fix duplication

There's no reason for both the TaxCalculator and the API to have nearly
the same logic... so I unified that while was in there.

2 files changed, 16 insertions, 26 deletions

diff --git a/lib/super_good/solidus_taxjar/api.rb b/lib/super_good/solidus_taxjar/api.rb
index ffefd5f..2504216 100644
--- a/lib/super_good/solidus_taxjar/api.rb
+++ b/lib/super_good/solidus_taxjar/api.rb
@@ -26,10 +26,6 @@ module SuperGood
         )
       end
 
-      private
-
-      attr_reader :taxjar_client
-
       def order_params(order)
         tax_address = order.tax_address
 
@@ -47,12 +43,20 @@ module SuperGood
               id: line_item.id,
               quantity: line_item.quantity,
               unit_price: line_item.price,
-              discount: -line_item.promo_total,
+              discount: discount(line_item),
               product_tax_code: line_item.tax_category&.tax_code
             }
           end
         }
       end
+
+      private
+
+      attr_reader :taxjar_client
+
+      def discount(line_item)
+        ::SuperGood::SolidusTaxJar.discount_calculator.new(line_item).discount
+      end
     end
   end
 end
diff --git a/lib/super_good/solidus_taxjar/tax_calculator.rb b/lib/super_good/solidus_taxjar/tax_calculator.rb
index 4a46953..54aace4 100644
--- a/lib/super_good/solidus_taxjar/tax_calculator.rb
+++ b/lib/super_good/solidus_taxjar/tax_calculator.rb
@@ -120,27 +120,13 @@ module SuperGood
       end
 
       def cache_key
-        tax_address = order.tax_address
-
-        {
-          to_country: tax_address.country.iso,
-          to_zip: tax_address.zipcode,
-          to_city: tax_address.city,
-          to_state: tax_address&.state&.abbr || tax_address.state_name,
-          to_street: tax_address.address1,
-
-          shipping: order.shipment_total,
-
-          line_items: order.line_items.map do |line_item|
-            {
-              id: line_item.id,
-              quantity: line_item.quantity,
-              unit_price: line_item.price,
-              discount: -line_item.promo_total,
-              product_tax_code: line_item.tax_category&.tax_code
-            }
-          end.hash
-        }
+        api.order_params(order).transform_values do |value|
+          case value
+          when Array, Hash then value.hash
+          else
+            value
+          end
+        end
       end
     end
   end