Improve Stock Coordinator Extensibility

core/app/models/spree/order_shipping.rb

@@ -21,7 +21,7 @@ def create_proposed_shipments
       raise Spree::Order::CannotRebuildShipments.new(I18n.t("spree.cannot_rebuild_shipments_shipments_not_pending"))
     else
       @order.shipments.destroy_all
-      @order.shipments.push(*Spree::Config.stock.coordinator_class.new(@order).shipments)
+      @order.shipments.push(*Spree::Config.stock.coordinator_class.new(@order, stock_locations:).shipments)
     end
   end
 
@@ -92,4 +92,11 @@ def ship(inventory_units:, stock_location:, address:, shipping_method:,
     Spree::Bus.publish(:carton_shipped, carton:)
     carton
   end
+
+  private
+
+  def stock_locations
+    # TODO: add stock location filtering and sorting here, pulling out what was
+    # done in the Coordinator class
+  end
 end

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

@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+
+module Spree
+  module Stock
+    class Coordinator
+      attr_reader :order
+
+      # @api private
+      attr_reader :inventory_units, :splitters, :stock_locations,
+        :filtered_stock_locations
+
+      def initialize(
+        order,
+        inventory_units: nil,
+        inventory_unit_builder_class: Spree::Config.stock.inventory_unit_builder_class,
+        splitters: Spree::Config.environment.stock_splitters,
+        allocator_class: Spree::Config.stock.allocator_class,
+        estimator_class: Spree::Config.stock.estimator_class,
+        location_filter_class: Spree::Config.stock.location_filter_class,
+        location_sorter_class: Spree::Config.stock.location_sorter_class,
+        stock_locations: nil
+      )
+        @order = order
+        @inventory_units = inventory_units
+
+        @inventory_unit_builder_class = inventory_unit_builder_class
+        @location_filter_class = location_filter_class
+        @location_sorter_class = location_sorter_class
+        @allocator_class = allocator_class
+
+        @estimator = estimator_class.new
+
+        @splitters = splitters
+      end
+
+      def shipments
+        @shipments ||= begin
+          packages = build_packages
+          packages = split_packages(packages)
+          shipments = build_shipments(packages)
+
+          # Make sure we don't add the proposed shipments to the order
+          order.shipments = order.shipments - shipments
+
+          shipments
+        end
+      end
+
+      private
+
+      def build_shipments(packages)
+        # Turn the Stock::Packages into a Shipment with rates
+        packages.map do |package|
+          shipment = package.shipment = package.to_shipment
+          shipment.shipping_rates = @estimator.shipping_rates(package)
+          shipment
+        end
+      end
+
+      def build_packages
+        filtered_stock_locations = @location_filter_class.new(Spree::StockLocation.all, order).filter
+        stock_locations = @location_sorter_class.new(filtered_stock_locations).sort
+
+        @inventory_units ||= inventory_unit_builder_class.new(order).units
+
+        @inventory_units_by_variant = @inventory_units.group_by(&:variant)
+        desired = Spree::StockQuantities.new(@inventory_units_by_variant.transform_values(&:count))
+        availability = Spree::Stock::Availability.new(
+          variants: desired.variants,
+          stock_locations:
+        )
+        allocator = @allocator_class.new(availability)
+
+        on_hand_packages, backordered_packages, leftover = allocator.allocate_inventory(desired)
+
+        raise Spree::Order::InsufficientStock.new(items: leftover.quantities) unless leftover.empty?
+
+        packages = stock_locations.map do |stock_location|
+          # Combine on_hand and backorders into a single package per-location
+          on_hand = on_hand_packages[stock_location.id] || Spree::StockQuantities.new
+          backordered = backordered_packages[stock_location.id] || Spree::StockQuantities.new
+
+          # Skip this location it has no inventory
+          next if on_hand.empty? && backordered.empty?
+
+          # Turn our raw quantities into a Stock::Package
+          package = Spree::Stock::Package.new(stock_location)
+          package.add_multiple(get_units(on_hand), :on_hand)
+          package.add_multiple(get_units(backordered), :backordered)
+
+          package
+        end.compact
+      end
+
+      def split_packages(initial_packages)
+        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
+
+      def get_units(quantities)
+        # Change our raw quantities back into inventory units
+        quantities.flat_map do |variant, quantity|
+          @inventory_units_by_variant[variant].shift(quantity)
+        end
+      end
+    end
+  end
+end
+