Add ability to change distributor based on whether products in the cart are available

app/controllers/spree/orders_controller_decorator.rb

@@ -35,7 +35,7 @@ Spree::OrdersController.class_eval do
 
     order = current_order(true)
 
-    if order.can_change_distributor?
+    if order.can_change_to_distributor?(distributor)
       order.distributor = distributor
       order.save!
     end

app/models/spree/order_decorator.rb

@@ -2,17 +2,43 @@ Spree::Order.class_eval do
   belongs_to :distributor, :class_name => 'Enterprise'
 
   before_validation :shipping_address_from_distributor
-  validate :can_change_distributor?, :if => :distributor_id_changed?
+  validate :change_distributor_validation, :if => :distributor_id_changed?
+  attr_accessible :distributor_id
 
   after_create :set_default_shipping_method
 
+  def change_distributor_validation
+    # Check that the line_items in the current order are available from a newly selected distributor
+    errors.add(:distributor_id, "The products in your cart are not available from '" + distributor.name + "'") unless can_change_to_distributor? distributor
+  end
+
+  def can_change_to_distributor? distributor
+    # Distributor may not be changed once an item has been added to the cart/order, unless all items are available from the specified distributor
+    line_items.empty? || (available_distributors || []).include?(distributor)
+  end
+
   def can_change_distributor?
     # Distributor may not be changed once an item has been added to the cart/order
     line_items.empty?
   end
 
+  def available_distributors
+    # Find all other enterprises which offer all product variants contained within the current order
+    distributors_with_all_variants = get_distributors_with_all_variants(Enterprise.all)
+  end
+
+  def get_distributors_with_all_variants(enterprises)
+    variants_in_current_order = line_items.map{ |li| li.variant }
+    distributors_with_all_variants = []
+    enterprises.each do |e|
+      variants_available_from_enterprise = ProductDistribution.find_all_by_distributor_id( e.id ).map{ |pd| pd.product.variants }.flatten
+      distributors_with_all_variants << e if ( variants_in_current_order - variants_available_from_enterprise ).empty?
+    end
+    distributors_with_all_variants
+  end
+
   def distributor=(distributor)
-    raise "You cannot change the distributor of an order with products" unless distributor == self.distributor || can_change_distributor?
+    raise "You cannot change the distributor of an order with products" unless distributor == self.distributor || can_change_to_distributor?(distributor)
     super(distributor)
   end
 
@@ -21,9 +47,9 @@ Spree::Order.class_eval do
     save!
   end
 
-
   def can_add_product_to_cart?(product)
-    can_change_distributor? || product.distributors.include?(distributor)
+    # Products may be added if no line items are currently in the cart or if the product is available from the current distributor
+    line_items.empty? || product.distributors.include?(distributor)
   end
 
   def set_variant_attributes(variant, attributes)

app/overrides/replace_delivery_address.rb

@@ -1,4 +1,9 @@
 Deface::Override.new(:virtual_path  => "spree/checkout/_address",
-            :replace       => "[data-hook='shipping_fieldset_wrapper']",
-            :partial       => "spree/checkout/distributor",
-            :name          => "delivery_address")
+            :replace    => "[data-hook='shipping_fieldset_wrapper']",
+            :partial    => "spree/checkout/distributor",
+            :name       => "replace_shipping_form")
+
+Deface::Override.new(:virtual_path  => "spree/checkout/edit",
+            :insert_after   => "[data-hook='checkout_summary_box']",
+            :partial        => "spree/checkout/other_available_distributors",
+            :name           => "other_available_distributors")

app/views/spree/checkout/_other_available_distributors.html.erb

@@ -0,0 +1,16 @@
+<div class="columns omega four" style="padding-top: 30px">
+  <%
+    other_available_distributors = @order.available_distributors
+	other_available_distributors.delete(@order.distributor)
+    unless other_available_distributors.empty?
+  %>
+    <%= form_for(@order) do |f| %>
+      <%= f.label :distributor_label, "Alternative distributors for this order:" %>
+	  <% available_distributors_array = other_available_distributors.map { |distributor| [distributor.name + ": " + distributor.address.address1 + ", " + distributor.address.city, distributor.id.to_i] } %>
+	  <%= f.select :distributor_id, options_for_select( available_distributors_array ) %>
+	  <%= f.submit "Change Distributor" %>
+	<% end %>
+  <% else %>
+	No alternative distributors available.
+  <% end %>
+</div>

app/views/spree/products/_source_sidebar.html.haml

@@ -11,7 +11,7 @@
     - order = current_order(false)
     - @distributors.each do |distributor|
       %li.nowrap
-        - if order.nil? || order.can_change_distributor?
+        - if order.nil? || order.can_change_to_distributor?(distributor)
           = link_to distributor.name, select_distributor_order_path(distributor)
         - elsif order.distributor == distributor
           = link_to distributor.name, [main_app, distributor]

spec/models/order_spec.rb

@@ -26,7 +26,7 @@ describe Spree::Order do
     subject.can_change_distributor?.should be_false
   end
 
-  it "raises an exception if distributor is changed without permission" do
+  it "checks that distributor is available when changing, and raises an exception if distributor is changed without permission" do
     d = create(:distributor_enterprise)
     p = create(:product, :distributors => [d])
     subject.distributor = d
@@ -34,6 +34,7 @@ describe Spree::Order do
 
     subject.add_variant(p.master, 1)
     subject.can_change_distributor?.should be_false
+    subject.should_receive(:available_distributors)
 
     expect do
       subject.distributor = nil
@@ -79,4 +80,63 @@ describe Spree::Order do
     li = Spree::LineItem.last
     li.max_quantity.should == 3
   end
+
+  context "finding alternative distributors" do
+    it "checks that variants are available" do
+      distributors_with_all_variants = double(:distributors_with_all_variants)
+      subject.should_receive(:get_distributors_with_all_variants).with(Enterprise.all)
+      subject.available_distributors
+    end
+
+    context "finding distributors which have the same variants" do
+      before(:each) do
+        @enterprise1 = FactoryGirl.create(:enterprise, id: 1)
+        subject.distributor = @enterprise1
+        @product1 = FactoryGirl.create(:product)
+        @product2 = FactoryGirl.create(:product)
+        @product3 = FactoryGirl.create(:product)
+        variant11 = FactoryGirl.create(:variant, product: @product1)
+        variant12 = FactoryGirl.create(:variant, product: @product1)
+        variant21 = FactoryGirl.create(:variant, product: @product2)
+        variant31 = FactoryGirl.create(:variant, product: @product3)
+        variant32 = FactoryGirl.create(:variant, product: @product3)
+
+        # Product Distributions
+        # Enterprise 1 sells product 1 and product 3
+        FactoryGirl.create(:product_distribution, product: @product1, distributor: @enterprise1)
+        FactoryGirl.create(:product_distribution, product: @product3, distributor: @enterprise1)
+
+        # Build the current order
+        line_item1 = FactoryGirl.create(:line_item, order: subject, variant: variant11)
+        line_item2 = FactoryGirl.create(:line_item, order: subject, variant: variant12)
+        line_item3 = FactoryGirl.create(:line_item, order: subject, variant: variant31)
+        subject.line_items = [line_item1,line_item2,line_item3]
+      end
+
+      it "matches the distributor enterprise of the current order" do
+        subject.get_distributors_with_all_variants([@enterprise1]).should == [@enterprise1]
+      end
+
+      it "does not match enterprises with no products available" do
+        test_enterprise = FactoryGirl.create(:enterprise, id: 2)
+        subject.get_distributors_with_all_variants([@enterprise1, test_enterprise]).should_not include test_enterprise
+      end
+
+      it "does not match enterprises with only some of the same variants in the current order available" do
+        test_enterprise = FactoryGirl.create(:enterprise, id: 2)
+        # Test Enterprise sells only product 1
+        FactoryGirl.create(:product_distribution, product: @product1, distributor: test_enterprise)
+        subject.get_distributors_with_all_variants([@enterprise1, test_enterprise]).should_not include test_enterprise
+      end
+
+      it "matches enteprises which offer all products in the current order" do
+        test_enterprise = FactoryGirl.create(:enterprise, id: 2)
+        # Enterprise 3 Sells Products 1, 2 and 3
+        FactoryGirl.create(:product_distribution, product: @product1, distributor: test_enterprise)
+        FactoryGirl.create(:product_distribution, product: @product2, distributor: test_enterprise)
+        FactoryGirl.create(:product_distribution, product: @product3, distributor: test_enterprise)
+        subject.get_distributors_with_all_variants([@enterprise1, test_enterprise]).should include test_enterprise
+     end
+    end
+  end
 end