WIP: Smooth scroll to checkout errors

app/assets/javascripts/darkswarm/controllers/checkout/accordion_controller.js.coffee

@@ -1,9 +1,10 @@
-Darkswarm.controller "AccordionCtrl", ($scope, storage, $timeout, CurrentHub) ->
+Darkswarm.controller "AccordionCtrl", ($scope, storage, $timeout, $document, CurrentHub) ->
   $scope.accordion = 
     details: true 
+    billing: false
     shipping: false
     payment: false
-    billing: false
+  $scope.accordionSections = ["details", "billing", "shipping", "payment"]
   storage.bind $scope, "accordion", {storeName: "accordion_#{$scope.order.id}#{CurrentHub.hub.id}#{$scope.order.user_id}"}
 
   $scope.show = (section)->
@@ -11,10 +12,17 @@ Darkswarm.controller "AccordionCtrl", ($scope, storage, $timeout, CurrentHub) ->
 
   $scope.$on 'purchaseFormInvalid', (event, form) ->
     # Scroll to first invalid section
-    # TODO: hide all first
-    # TODO: Use Object.keys($scope.accordion)
-    sections = ["details", "billing", "shipping", "payment"]
-    for section in sections
+    for section in $scope.accordionSections
       if not form[section].$valid
         $scope.show section
+
+        # If we call scrollTo() directly after show(), when one of the accordions above the
+        # scroll location is closed by show(), scrollTo() will scroll to the old location of
+        # the element. Putting this in a zero-length timeout is enough delay for the DOM to
+        # have updated.
+        $timeout ->
+          # Scrolling is confused by our position:fixed top bar - add an offset to scroll
+          # to the correct location, plus 5px buffer
+          offset_height = $("nav.top-bar").height() + 5
+          $document.scrollTo $("##{section}"), offset_height, 500
         break