Working untested version for 1-1-stable

app/models/spree/line_item_decorator.rb

@@ -1,16 +1,16 @@
 Spree::LineItem.class_eval do
-  def update_adjustment(adjustment, source)
-    current_amount = adjustment.amount
-    adjustment.amount = if adjustment.adjustable(true).line_items.include? adjustment.source
+  def update_adjustment(adjustment, source) #source being the order
+    new_amount = if adjustment.originator and source.line_items.include? adjustment.originator
       calculate_core_charge
     else
       0
     end
-    if current_amount != adjustment.amount
-      Spree::Adjustment.skip_callback :save, :after, :update_adjustable
-      adjustment.save
-      Spree::Adjustment.set_callback :save, :after, :update_adjustable
-    end
+
+    adjustment.update_attribute_without_callbacks(:amount, new_amount)
+
+   # Spree::Adjustment.skip_callback :save, :after, :update_adjustable
+   # adjustment.save
+   # Spree::Adjustment.set_callback :save, :after, :update_adjustable
    end
 
   def eligible?(source = nil)

app/models/spree/order_decorator.rb

@@ -1,26 +1,36 @@
 Spree::Order.class_eval do
 
-  def core_charges
-    adjustments.where(:source_type => 'Spree::LineItem')
-  end
-
+  # Called each time an orderis updated
   def create_core_charges
-    applicable_charges, charges_to_destroy = self.core_charges.partition{|cc| cc.originator && cc.originator.eligible? }
-    charges_to_destroy.each(&:delete)
-    line_item_with_core_charge_ids = applicable_charges.map(&:source_id)
-
-    self.line_items.reload.each do |li|
-      next unless li.product.core_amount
-
-      self.core_charges << Spree::Adjustment.create({
-        :label =>  "#{I18n.t(:core_charge)} [#{li.variant.sku}]",
-        :source => li,
-        :adjustable => self,
-        :originator => li,
-        :amount => li.calculate_core_charge,
-        :eligible => true
-      }) unless line_item_with_core_charge_ids.include?(li.id)
+    to_keep, to_destroy = adjustments.core.partition{|x| x.originator and x.originator.eligible?}
+    to_destroy.each(&:delete)
+    core_variant_ids = to_keep.map{|x| x.originator.variant_id }
+
+    Spree::Adjustment.skip_callback :save, :after, :update_adjustable
+
+    line_items.each do |li|
+      next unless li.product.core_amount # The product has no core charge associated with it
+      next if core_variant_ids.include? li.variant_id # The charge for this line item already exists
+
+      new_core_charge = Spree::Adjustment.new
+      new_core_charge.label = "#{I18n.t(:core_charge)} [#{li.variant.sku}]"
+      new_core_charge.source = li
+      new_core_charge.adjustable = self
+      new_core_charge.originator = li
+      new_core_charge.amount = li.calculate_core_charge
+      new_core_charge.eligible = true
+
+      new_core_charge.save
     end
+
+    Spree::Adjustment.set_callback :save, :after, :update_adjustable
+
+    update_totals
+
+    update_attributes_without_callbacks({
+      :adjustment_total => adjustment_total,
+      :total => total
+    })
   end
 
 end

lib/spree_core_charges.rb

@@ -1,20 +1,2 @@
 require 'spree_core'
-
-module Spree
-  module CoreCharges
-    class Engine < Rails::Engine
-      isolate_namespace Spree
-      engine_name 'spree_core_charges'
-
-      def self.activate
-        Dir.glob(File.join(File.dirname(__FILE__), "../app/**/*_decorator*.rb")) do |c|
-          Rails.configuration.cache_classes ? require(c) : load(c)
-        end
-        Order.register_update_hook('create_core_charges')
-      end
-
-      config.autoload_paths += %W(#{config.root}/lib #{config.root}/app/overrides)
-      config.to_prepare &method(:activate).to_proc
-    end
-  end
-end
+require 'spree_core_charges/engine'

lib/spree_core_charges/engine.rb

@@ -0,0 +1,19 @@
+module Spree
+  module CoreCharges
+    class Engine < Rails::Engine
+      isolate_namespace Spree
+      engine_name 'spree_core_charges'
+
+      def self.activate
+        Dir.glob(File.join(File.dirname(__FILE__), "../../app/**/*_decorator*.rb")) do |c|
+          Rails.configuration.cache_classes ? require(c) : load(c)
+        end
+
+        Spree::Order.register_update_hook(:create_core_charges)
+      end
+
+      config.autoload_paths += %W(#{config.root}/lib #{config.root}/app/overrides)
+      config.to_prepare &method(:activate).to_proc
+    end
+  end
+end