Make product modal show close button only if there is a scroll bar

app/assets/javascripts/darkswarm/controllers/products/product_node_controller.js.coffee

@@ -4,3 +4,9 @@ Darkswarm.controller "ProductNodeCtrl", ($scope, $modal, FilterSelectorsService)
   $scope.triggerProductModal = ->
     $scope.productPropertySelectors = FilterSelectorsService.createSelectors()
     $modal.open(templateUrl: "product_modal.html", scope: $scope)
+
+  $scope.hasVerticalScrollBar = (selector) ->
+    elem = angular.element(document.querySelector(selector))
+    return false unless elem[0]
+
+    elem[0].scrollHeight > elem[0].clientHeight

app/assets/javascripts/templates/product_modal.html.haml

@@ -19,6 +19,6 @@
 
 %ng-include{src: "'partials/close.html'"}
 
-.buttons
+.buttons{ "ng-show": "hasVerticalScrollBar('.reveal-modal')" }
   .button.bottom-close-button{"ng-click" => "$close()"}
     = t('js.shop.products.product_modal.close')

spec/javascripts/unit/darkswarm/controllers/products/product_node_controller_spec.js.coffee

@@ -16,3 +16,24 @@ describe "ProductNodeCtrl", ->
 
   it "puts a reference to supplier in the scope", ->
     expect(scope.enterprise).toBe product.supplier
+
+  describe "#hasVerticalScrollBar", ->
+    it "returns false if modal element is not found", ->
+      spyOn(angular, 'element').and.returnValue([])
+
+      expect(scope.hasVerticalScrollBar()).toBe false
+
+    it "returns false if scrollHeight is equal to clientHeight", ->
+      spyOn(angular, 'element').and.returnValue([{ scrollHeight: 100, clientHeight: 100 }])
+
+      expect(scope.hasVerticalScrollBar()).toBe false
+
+    it "returns false if scrollHeight is smaller than clientHeight", ->
+      spyOn(angular, 'element').and.returnValue([{ scrollHeight: 50, clientHeight: 100 }])
+
+      expect(scope.hasVerticalScrollBar()).toBe false
+
+    it "returns true if scrollHeight is bigger than clientHeight", ->
+      spyOn(angular, 'element').and.returnValue([{ scrollHeight: 100, clientHeight: 50 }])
+
+      expect(scope.hasVerticalScrollBar()).toBe true