add fix_grades management command

Shows any lost grades in a proctored and randomized edx course. Has a
dangerous db/grade-modifying option that will attempt to automatically
repair the issues:

--fix-it-for-real-i-mean-it

lms/djangoapps/courseware/management/commands/fix_grades.py

+import json
+import itertools
+
+from pprint import pprint
+
+from django.db.models import F
+from django.contrib.auth.models import User
+from django.core.management.base import BaseCommand, CommandError, make_option
+
+from courseware.grades import iterate_grades_for
+from courseware.models import StudentModule, StudentModuleHistory
+from courseware.module_tree_reset import ProctorModuleInfo
+
+from xmodule.modulestore import Location
+
+
+class Command(BaseCommand):
+    args = "<course_id>"
+    help = """Show and optionally fix any lost grades for 3.091r"""
+    option_list = BaseCommand.option_list + (
+        make_option('--fix-it-for-real-i-mean-it',
+                    dest='fix_it_for_real_i_mean_it',
+                    action='store_true',
+                    default=False,
+                    help='Restore lost grades'),
+    )
+
+    def get_lost_grades(self):
+        grades = list(iterate_grades_for(self.pmi.course.id, User.objects.all()))
+
+        history_entries = StudentModuleHistory.objects.filter(
+            # test if results are same without these three Q's
+            # (seems to be the case)
+            #Q(state__contains='"attempts"') &
+            #Q(state__contains='"correct_map"') &
+            #Q(state__contains='"student_answers"'),
+            grade__isnull=False, max_grade__isnull=False,
+            grade=F("max_grade"),
+        )
+
+        lost_grades = {}
+
+        for user, gradeset, err_msg in grades:
+            if err_msg:
+                print "!!! GRADING FAILURE FOR USER '%s': %s" % (user, err_msg)
+                continue
+            entries = history_entries.filter(student_module__student=user)
+            _scores = gradeset['totaled_scores'].values()
+            total_scores = dict([(i.section, i) for i in
+                                 itertools.chain.from_iterable(_scores)])
+            for e in entries:
+                loc = Location(e.student_module.module_state_key)
+                sec_name = loc.name.split(':')[1]
+                score = total_scores.get(sec_name)
+                if score is None:
+                    continue
+                if score.earned != score.possible:
+                    if e.grade != e.max_grade:
+                        raise Exception("e.grade = %s != e.max_grade = %s" %
+                                        (e.grade, e.max_grade))
+                    lost = lost_grades.get(user.username, {})
+                    lost[sec_name] = [score.earned, score.possible, e.grade,
+                                      e.max_grade, e]
+                    lost_grades[user.username] = lost
+
+        return lost_grades
+
+    def fix_grades(self, lost_grades):
+        for user in lost_grades:
+            lost_dict = lost_grades.get(user)
+            rpmod_dict = dict([(i.location.name, i) for i in self.pmi.rpmods])
+            for section in lost_dict:
+                lost = lost_dict.get(section)
+                pmod = rpmod_dict.get(section)
+                rloc = pmod.get_children()[0].get_children()[0].location.url()
+                rsm = StudentModule.objects.get(student__username=user,
+                                               module_state_key=rloc)
+                state = json.loads(rsm.state)
+                history = state.get('history', []) or []
+                successful_submission = lost[-1]
+                sm = lost[-1].student_module
+                choice = sm.module_state_key
+                if choice not in history:
+                    history.append(choice)
+                state['choice'] = choice
+                state['history'] = history
+                rsm.state = json.dumps(state)
+                rsm.save()
+                if sm.grade != successful_submission.grade:
+                    sm.grade = successful_submission.grade
+                    sm.state = successful_submission.state
+                    sm.save()
+
+    def handle(self, *args, **options):
+        if len(args) != 1:
+            raise CommandError("insufficient arguments")
+        self.pmi = ProctorModuleInfo(args[0])
+        lost_grades = self.get_lost_grades()
+        total = sum([len(i.keys()) for i in lost_grades.values()])
+        pprint(lost_grades)
+        print 'Total: %s' % total
+        fix_it_for_real_i_mean_it = options.get('fix_it_for_real_i_mean_it')
+        if fix_it_for_real_i_mean_it:
+            print '!!! Fixing grades now...'
+            self.fix_grades(lost_grades)