Minimal refactoring for rolling certificates

* Studio advanced setting added, "certificates_show_before_end", which
  determines whether a course should permit certificates to be
  downloadable by students before the coures's end date has passed.
* Modifications to dashboard view and templates to allow display of
  certificate download links before course has ended. (XXX: may declare
  failing students as failing before the course has ended.)
* To test, turn the setting on in a course which hasn't ended yet, and
  force certificate generation for a student, then check their
  dashboard.
* TODO:
  - needs tests
  - needs pep8/pylint

common/djangoapps/student/views.py

@@ -31,7 +31,6 @@ from django_future.csrf import ensure_csrf_cookie
 from django.utils.http import cookie_date, base36_to_int
 from django.utils.translation import ugettext as _
 from django.views.decorators.http import require_POST, require_GET
-from django.contrib.admin.views.decorators import staff_member_required
 
 from ratelimitbackend.exceptions import RateLimitException
 
@@ -185,7 +184,7 @@ def cert_info(user, course):
     'survey_url': url, only if show_survey_button is True
     'grade': if status is not 'processing'
     """
-    if not course.has_ended():
+    if not course.may_certify():
         return {}
 
     return _cert_info(user, course, certificate_status_for_student(user, course.id))

common/lib/xmodule/xmodule/course_module.py

@@ -350,6 +350,9 @@ class CourseFields(object):
     )
     enrollment_domain = String(help="External login method associated with user accounts allowed to register in course",
                                scope=Scope.settings)
+    certificates_show_before_end = Boolean(help="True if students may download certificates before course end",
+                                           scope=Scope.settings,
+                                           default=False)
     course_image = String(
         help="Filename of the course image",
         scope=Scope.settings,
@@ -572,6 +575,12 @@ class CourseDescriptor(CourseFields, SequenceDescriptor):
 
         return datetime.now(UTC()) > self.end
 
+    def may_certify(self):
+        """
+        Return True if it is acceptable to show the student a certificate download link
+        """
+        return self.certificates_show_before_end or self.has_ended()
+
     def has_started(self):
         return datetime.now(UTC()) > self.start
 

lms/djangoapps/certificates/views.py

@@ -62,6 +62,7 @@ def update_certificate(request):
     This view should only ever be accessed by the xqueue server
     """
 
+    status = CertificateStatuses
     if request.method == "POST":
 
         xqueue_body = json.loads(request.POST.get('xqueue_body'))

lms/templates/dashboard/_dashboard_certificate_information.html

@@ -14,7 +14,9 @@ else:
 %>
 <div class="message message-status ${status_css_class} is-shown">
 
-% if cert_status['status'] == 'processing':
+% if course.may_certify() and cert_status['status'] == 'processing':
+      <p class="message-copy">${_("Your final standing is unrequested or unavailable at this time.")}</p>
+% elif cert_status['status'] == 'processing':
       <p class="message-copy">${_("Final course details are being wrapped up at this time. Your final standing will be available shortly.")}</p>
 % elif cert_status['status'] in ('generating', 'ready', 'notpassing', 'restricted'):
       <p class="message-copy">${_("Your final grade:")}

lms/templates/dashboard/_dashboard_course_listing.html

@@ -57,7 +57,7 @@
         </h3>
       </hgroup>
 
-      % if course.has_ended() and cert_status and not enrollment.mode == 'audit':
+      % if course.may_certify() and cert_status and not enrollment.mode == 'audit':
       <%include file='_dashboard_certificate_information.html' args='cert_status=cert_status,course=course, enrollment=enrollment'/>
       % endif