Introduce new middleware stock coordinator

core/app/models/spree/exchange.rb

@@ -22,7 +22,10 @@ def display_amount
 
     def perform!
       begin
-        shipments = Spree::Config.stock.coordinator_class.new(@order, @reimbursement_objects.map(&:build_exchange_inventory_unit)).shipments
+        shipments = Spree::Config.stock.coordinator_class.new(
+          @order,
+          inventory_units: @reimbursement_objects.map(&:build_exchange_inventory_unit)
+        ).shipments
       rescue Spree::Order::InsufficientStock
         raise UnableToCreateShipments.new("Could not generate shipments for all items. Out of stock?")
       end

core/app/models/spree/order.rb

@@ -513,9 +513,9 @@ def create_proposed_shipments
     end
 
     def create_shipments_for_line_item(line_item)
-      units = Spree::Config.stock.inventory_unit_builder_class.new(self).missing_units_for_line_item(line_item)
+      inventory_units = Spree::Config.stock.inventory_unit_builder_class.new(self).missing_units_for_line_item(line_item)
 
-      Spree::Config.stock.coordinator_class.new(self, units).shipments.each do |shipment|
+      Spree::Config.stock.coordinator_class.new(self, inventory_units:).shipments.each do |shipment|
         shipments << shipment
       end
     end

core/app/models/spree/stock/coordinator.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Spree
+  module Stock
+    class Coordinator
+      def initialize(order, inventory_units: nil)
+        @context = {order:, inventory_units:}
+        @order = order
+
+        Middleware::InventoryUnit.new.call(@context)
+        Middleware::InventoryUnitGroup.new.call(@context)
+        Middleware::StockLocation.new.call(@context)
+        Middleware::Desired.new.call(@context)
+        Middleware::Availability.new.call(@context)
+      end
+
+      def shipments
+        @shipments ||= begin
+                         Middleware::Allocate.new.call(@context)
+                         Middleware::Package.new.call(@context)
+                         Middleware::Shipment.new.call(@context)
+
+                         shipments = @context[:shipments]
+
+                         # Make sure we don't add the proposed shipments to the order
+                         @order.shipments = @order.shipments - shipments
+
+                         shipments
+                       end
+      end
+    end
+  end
+end

core/app/models/spree/stock/middleware/allocate.rb

@@ -0,0 +1,17 @@
+module Spree
+  module Stock
+    module Middleware
+      class Allocate
+        def call(context)
+          allocator = Spree::Config.stock.allocator_class.new(context[:availability])
+          on_hand_packages, backordered_packages, leftover = allocator.allocate_inventory(context[:desired])
+
+          raise Spree::Order::InsufficientStock.new(items: leftover.quantities) unless leftover.empty?
+
+          context[:on_hand_packages] = on_hand_packages
+          context[:backordered_packages] = backordered_packages
+        end
+      end
+    end
+  end
+end

core/app/models/spree/stock/middleware/availability.rb

@@ -0,0 +1,14 @@
+module Spree
+  module Stock
+    module Middleware
+      class Availability
+        def call(context)
+          context[:availability] = Spree::Stock::Availability.new(
+            variants: context[:desired].variants,
+            stock_locations: context[:stock_locations]
+          )
+        end
+      end
+    end
+  end
+end

core/app/models/spree/stock/middleware/desired.rb

@@ -0,0 +1,11 @@
+module Spree
+  module Stock
+    module Middleware
+      class Desired
+        def call(context)
+          context[:desired] = Spree::StockQuantities.new(context[:inventory_unit_groups].transform_values(&:count))
+        end
+      end
+    end
+  end
+end

core/app/models/spree/stock/middleware/inventory_unit.rb

@@ -0,0 +1,15 @@
+module Spree
+  module Stock
+    module Middleware
+      class InventoryUnit
+        def call(context)
+          order = context[:order]
+
+          context[:inventory_units] = context[:inventory_units] ||
+            Spree::Config.stock.inventory_unit_builder_class.new(order).units
+        end
+      end
+    end
+  end
+end
+

core/app/models/spree/stock/middleware/inventory_unit_group.rb

@@ -0,0 +1,11 @@
+module Spree
+  module Stock
+    module Middleware
+      class InventoryUnitGroup
+        def call(context)
+          context[:inventory_unit_groups] = context[:inventory_units].group_by(&:variant)
+        end
+      end
+    end
+  end
+end

core/app/models/spree/stock/middleware/package.rb

@@ -0,0 +1,41 @@
+module Spree
+  module Stock
+    module Middleware
+      class Package
+        def call(context)
+          packages = context[:stock_locations].map do |stock_location|
+            on_hand = context[:on_hand_packages][stock_location.id] || Spree::StockQuantities.new
+            backordered = context[:backordered_packages][stock_location.id] || Spree::StockQuantities.new
+
+            next if on_hand.empty? && backordered.empty?
+
+            package = Spree::Stock::Package.new(stock_location)
+            package.add_multiple(get_units(context, on_hand), :on_hand)
+            package.add_multiple(get_units(context, backordered), :backordered)
+
+            package
+          end.compact
+
+          context[:packages] = split_packages(packages)
+        end
+
+        private
+
+        def get_units(context, quantities)
+          quantities.flat_map do |variant, quantity|
+            context[:inventory_unit_groups][variant].shift(quantity)
+          end
+        end
+
+        def split_packages(initial_packages)
+          splitters = Spree::Config.environment.stock_splitters
+
+          initial_packages.flat_map do |initial_package|
+            stock_location = initial_package.stock_location
+            Spree::Stock::SplitterChain.new(stock_location, splitters).split([initial_package])
+          end
+        end
+      end
+    end
+  end
+end

core/app/models/spree/stock/middleware/shipment.rb

@@ -0,0 +1,15 @@
+module Spree
+  module Stock
+    module Middleware
+      class Shipment
+        def call(context)
+          context[:shipments] = context[:packages].map do |package|
+            shipment = package.shipment = package.to_shipment
+            shipment.shipping_rates = Spree::Config.stock.estimator_class.new.shipping_rates(package)
+            shipment
+          end
+        end
+      end
+    end
+  end
+end

core/app/models/spree/stock/middleware/stock_location.rb

@@ -0,0 +1,24 @@
+module Spree
+  module Stock
+    module Middleware
+      class StockLocation
+        def call(context)
+          filtered_stock_locations = Spree::Config.stock.location_filter_class.new(
+            load_stock_locations, context[:order]
+          ).filter
+          sorted_stock_locations = Spree::Config.stock.location_sorter_class.new(
+            filtered_stock_locations
+          ).sort
+
+          context[:stock_locations] = sorted_stock_locations
+        end
+
+        private
+
+        def load_stock_locations
+          Spree::StockLocation.all
+        end
+      end
+    end
+  end
+end

core/app/models/spree/stock/simple_coordinator.rb

@@ -27,7 +27,14 @@ class SimpleCoordinator
         :filtered_stock_locations, :inventory_units_by_variant, :desired,
         :availability, :allocator, :packages
 
-      def initialize(order, inventory_units = nil)
+      def initialize(order, inventory_units_deprecated = nil, inventory_units: nil)
+        if inventory_units_deprecated
+          Spree.deprecator.warn "Using the `inventory_units` positional " \
+            "argument is deprecated in favor of using the keyword argument. "
+
+          inventory_units ||= inventory_units_deprecated
+        end
+
         @order = order
         @inventory_units =
           inventory_units || Spree::Config.stock.inventory_unit_builder_class.new(order).units