Add explanatory copy to TeacherCoursesView

app/collections/Prepaids.coffee

@@ -0,0 +1,23 @@
+CocoCollection = require 'collections/CocoCollection'
+Prepaid = require 'models/Prepaid'
+
+sum = (numbers) -> _.reduce(numbers, (a, b) -> a + b)
+
+module.exports = class Prepaids extends CocoCollection
+  model: Prepaid
+
+  url: "/db/prepaid"
+  
+  totalMaxRedeemers: ->
+    sum((prepaid.get('maxRedeemers') for prepaid in @models)) or 0
+    
+  totalRedeemers: ->
+    sum((_.size(prepaid.get('redeemers')) for prepaid in @models)) or 0
+    
+  totalAvailable: -> Math.max(@totalMaxRedeemers() - @totalRedeemers(), 0)
+
+  fetchByCreator: (creatorID, opts) ->
+    opts ?= {}
+    opts.data ?= {}
+    opts.data.creator = creatorID
+    @fetch opts

app/templates/courses/teacher-courses-view.jade

@@ -54,6 +54,17 @@ block content
 
   br
   .section-header Available Courses
+  
+  p.text-center
+    strong.spr Unused enrollments available:
+    strong.spr= view.prepaids.totalAvailable()
+    a.btn.btn-success.btn(href="/courses/purchase") Purchase Enrollments
+    
+  p
+    | All students get access to Introduction to Computer Science for free.
+    | One enrollment per student is required to assign them to paid CodeCombat courses.
+    | A single student does not need multiple enrollments to access all paid courses.
+    
   .container-fluid
     - var courses = view.courses.models;
     - var i = 0;

app/views/courses/ActivateLicensesModal.coffee

@@ -1,7 +1,7 @@
 ModalView = require 'views/core/ModalView'
 template = require 'templates/courses/activate-licenses-modal'
 CocoCollection = require 'collections/CocoCollection'
-Prepaid = require 'models/Prepaid'
+Prepaids = require 'collections/Prepaids'
 User = require 'models/User'
 
 module.exports = class ActivateLicensesModal extends ModalView
@@ -16,12 +16,10 @@ module.exports = class ActivateLicensesModal extends ModalView
     @classroom = options.classroom
     @users = options.users
     @user = options.user
-    @prepaids = new CocoCollection([], { url: "/db/prepaid", model: Prepaid })
+    @prepaids = new Prepaids()
-    sum = (numbers) -> _.reduce(numbers, (a, b) -> a + b)
-    @prepaids.totalMaxRedeemers = -> sum((prepaid.get('maxRedeemers') for prepaid in @models)) or 0
-    @prepaids.totalRedeemers = -> sum((_.size(prepaid.get('redeemers')) for prepaid in @models)) or 0
     @prepaids.comparator = '_id'
-    @supermodel.loadCollection(@prepaids, 'prepaids', {data: {creator: me.id}})
+    @prepaids.fetchByCreator(me.id)
+    @supermodel.loadCollection(@prepaids, 'prepaids')
     
   afterRender: ->
     super()

app/views/courses/TeacherCoursesView.coffee

@@ -10,6 +10,7 @@ CourseInstance = require 'models/CourseInstance'
 RootView = require 'views/core/RootView'
 template = require 'templates/courses/teacher-courses-view'
 ClassroomSettingsModal = require 'views/courses/ClassroomSettingsModal'
+Prepaids = require 'collections/Prepaids'
 
 module.exports = class TeacherCoursesView extends RootView
   id: 'teacher-courses-view'
@@ -32,6 +33,11 @@ module.exports = class TeacherCoursesView extends RootView
     @courseInstances.comparator = 'courseID'
     @courseInstances.sliceWithMembers = -> return @filter (courseInstance) -> _.size(courseInstance.get('members')) and courseInstance.get('classroomID')
     @supermodel.loadCollection(@courseInstances, 'course_instances', {data: {ownerID: me.id}})
+    @prepaids = new Prepaids()
+    @prepaids.comparator = '_id'
+    if not me.isAnonymous()
+      @prepaids.fetchByCreator(me.id)
+      @supermodel.loadCollection(@prepaids, 'prepaids') # just registers
     @members = new CocoCollection([], { model: User })
     @listenTo @members, 'sync', @render
     @