Columns service holds a column count and notifies rootscope when it changes

app/assets/javascripts/admin/index_utils/directives/toggle_column.js.coffee

@@ -1,11 +1,8 @@
-angular.module("admin.indexUtils").directive "ofnToggleColumn", ->
+angular.module("admin.indexUtils").directive "ofnToggleColumn", (Columns) ->
   link: (scope, element, attrs) ->
     element.addClass "selected" if scope.column.visible
+
     element.click "click", ->
       scope.$apply ->
-        if scope.column.visible
-          scope.column.visible = false
-          element.removeClass "selected"
-        else
-          scope.column.visible = true
-          element.addClass "selected"
+        Columns.toggleColumn(scope.column)
+        element.toggleClass "selected"

app/assets/javascripts/admin/index_utils/services/columns.js.coffee

@@ -1,8 +1,18 @@
-angular.module("admin.indexUtils").factory 'Columns', ->
+angular.module("admin.indexUtils").factory 'Columns', ($rootScope) ->
   new class Columns
     columns: {}
+    visibleCount: 0
 
-    setColumns: (columns) ->
+    setColumns: (columns) =>
       @columns = {}
       @columns[name] = column for name, column of columns
+      @calculateVisibleCount()
       @columns
+
+    toggleColumn: (column) =>
+      column.visible = !column.visible
+      @calculateVisibleCount()
+
+    calculateVisibleCount: =>
+      @visibleCount = (column for name, column of @columns when column.visible).length
+      $rootScope.$broadcast "columnCount:changed", @visibleCount

spec/javascripts/unit/admin/index_utils/services/columns_spec.js.coffee

@@ -7,9 +7,34 @@ describe "Columns service", ->
     inject (_Columns_) ->
       Columns = _Columns_
 
-    Columns.columns = ["something"]
-
   describe "setting columns", ->
     it "sets resets @columns and copies each column of the provided object across", ->
       Columns.setColumns({ name: { visible: true } })
       expect(Columns.columns).toEqual { name: { visible: true } }
+
+    it "calls calculateVisibleCount", ->
+      spyOn(Columns, "calculateVisibleCount")
+      Columns.setColumns({ name: { visible: true } })
+      expect(Columns.calculateVisibleCount).toHaveBeenCalled()
+
+  describe "toggling a column", ->
+    it "switches the visibility of the given column", ->
+      column = { visible: false }
+      Columns.toggleColumn(column)
+      expect(column.visible).toBe true
+
+    it "calls calculateVisibleCount", ->
+      spyOn(Columns, "calculateVisibleCount")
+      Columns.toggleColumn({ visible: false })
+      expect(Columns.calculateVisibleCount).toHaveBeenCalled()
+
+  describe "calculating visibleCount", ->
+    it "counts the number of columns ", ->
+      Columns.columns = { col1: { visible: false }, col2: { visible: true }, col3: { visible: true }, col4: { visible: false } }
+      Columns.calculateVisibleCount()
+      expect(Columns.visibleCount).toBe 2
+
+    it "$broadcasts the updated visible count to $rootScope", inject ($rootScope) ->
+      spyOn($rootScope, "$broadcast")
+      Columns.calculateVisibleCount()
+      expect($rootScope.$broadcast).toHaveBeenCalled()