Adding XQueueCertificate interface.

Adding, removing and updating certs

lms/djangoapps/certificates/queue.py

+from django.utils.simplejson import dumps
+from django.core.management.base import BaseCommand, CommandError
+from certificates.models import GeneratedCertificate
+from certificates.models import certificate_status_for_student
+from courseware import grades, courses
+from django.contrib.auth.models import User
+from django.test.client import RequestFactory
+from pprint import pprint
+from capa.xqueue_interface import XQueueInterface
+from capa.xqueue_interface import make_xheader, make_hashkey
+from django.conf import settings
+from requests.auth import HTTPBasicAuth
+from student.models import UserProfile
+import json
+import random
+import logging
+
+
+def add_cert_to_queue(student, course_id, xqueue_interface, request=None):
+    """
+    Update or create a new GeneratedCertificates:
+      
+    If certificate generation is in progress this function will
+    return None. 
+
+    If certificate generation was completed for the user this
+    will add a request to delete the existing certificate.
+
+    A new certificate request will be made if the student's
+    grade is not None
+    """
+    log = logging.getLogger("mitx.certificates")
+    if request is None:
+        factory = RequestFactory()
+        request = factory.get('/')
+
+    cert_status = certificate_status_for_student(student, course_id)
+    if cert_status['status'] == 'generating':
+        return None
+
+    if cert_status['status'] == 'downloadable':
+        generated_certificate = GeneratedCertificate.objects.get(
+            user=student, course_id=course_id)
+        generated_certificate.status = 'unavailable'
+        key = generated_certificate.key
+        username = generated_certificate.user.username
+        generated_certificate.save()
+
+        contents = {
+             'remove': True,
+             'verify_uuid': cert.verify_uuid,
+             'download_uuid': cert.download_uuid,
+             'key': cert.key,
+             'username': cert.user.username
+        }
+        xheader = make_xheader('http://sandbox-jrjarvis-001.m.edx.org/certificate', key, 'test-pull')
+        (error, msg) = xqueue_interface.send_to_queue(header=xheader,
+                             body=json.dumps(contents))
+
+    # grade the student
+    course = courses.get_course_by_id(course_id)
+    grade = grades.grade(student, request, course)
+
+    if grade['grade'] is not None:
+        cert, created = GeneratedCertificate.objects.get_or_create(
+               user=student, course_id=course_id)
+        profile = UserProfile.objects.get(user=student)
+
+        key = make_hashkey(random.random())
+
+        cert.status = 'generating' 
+        cert.grade = grade['percent']
+        cert.user = student
+        cert.course_id = course_id
+        cert.key = key
+        cert.save()
+
+        contents = {
+            'username': student.username,
+            'course_id': course_id,
+            'name': profile.name,
+        }
+        xheader = make_xheader('http://sandbox-jrjarvis-001.m.edx.org/update_certificate', key, 'test-pull')
+        (error, msg) = xqueue_interface.send_to_queue(header=xheader,
+                             body=json.dumps(contents))
+        if error:
+            log.critical('Unable to send message')
+