Add management command for backpopulating missing program credentials

This command triggers program certification tasks for any users in the system who may qualify for a program credential. ECOM-3924.

openedx/core/djangoapps/programs/management/commands/backpopulate_program_credentials.py

+"""Management command for backpopulating missing program credentials."""
+from collections import namedtuple
+import logging
+
+from django.core.management import BaseCommand, CommandError
+from django.db.models import Q
+from opaque_keys.edx.keys import CourseKey
+from provider.oauth2.models import Client
+
+from certificates.models import GeneratedCertificate  # pylint: disable=import-error
+from openedx.core.djangoapps.programs.models import ProgramsApiConfig
+from openedx.core.djangoapps.programs.tasks.v1.tasks import award_program_certificates
+from openedx.core.djangoapps.programs.utils import get_programs
+
+
+# TODO: Log to console, even with debug mode disabled?
+logger = logging.getLogger(__name__)  # pylint: disable=invalid-name
+RunMode = namedtuple('RunMode', ['course_key', 'mode_slug'])
+
+
+class Command(BaseCommand):
+    """Management command for backpopulating missing program credentials.
+
+    The command's goal is to pass a narrow subset of usernames to an idempotent
+    Celery task for further (parallelized) processing.
+    """
+    help = 'Backpopulate missing program credentials.'
+    client = None
+    run_modes = None
+    usernames = None
+
+    def add_arguments(self, parser):
+        parser.add_argument(
+            '-c', '--commit',
+            action='store_true',
+            dest='commit',
+            default=False,
+            help='Submit tasks for processing.'
+        )
+
+    def handle(self, *args, **options):
+        programs_config = ProgramsApiConfig.current()
+        self.client = Client.objects.get(name=programs_config.OAUTH2_CLIENT_NAME)
+
+        if self.client.user is None:
+            msg = (
+                'No user is associated with the {} OAuth2 client. '
+                'A service user is necessary to make requests to the Programs API. '
+                'No tasks have been enqueued. '
+                'Associate a user with the client and try again.'
+            ).format(programs_config.OAUTH2_CLIENT_NAME)
+
+            raise CommandError(msg)
+
+        self._load_run_modes()
+
+        logger.info('Looking for users who may be eligible for a program certificate.')
+
+        self._load_usernames()
+
+        if options.get('commit'):
+            logger.info('Enqueuing program certification tasks for %d candidates.', len(self.usernames))
+        else:
+            logger.info(
+                'Found %d candidates. To enqueue program certification tasks, pass the -c or --commit flags.',
+                len(self.usernames)
+            )
+            return
+
+        succeeded, failed = 0, 0
+        for username in self.usernames:
+            try:
+                award_program_certificates.delay(username)
+            except:  # pylint: disable=bare-except
+                failed += 1
+                logger.exception('Failed to enqueue task for user [%s]', username)
+            else:
+                succeeded += 1
+                logger.debug('Successfully enqueued task for user [%s]', username)
+
+        logger.info(
+            'Done. Successfully enqueued tasks for %d candidates. '
+            'Failed to enqueue tasks for %d candidates.',
+            succeeded,
+            failed
+        )
+
+    def _load_run_modes(self):
+        """Find all run modes which are part of a program."""
+        programs = get_programs(self.client.user)
+        self.run_modes = self._flatten(programs)
+
+    def _flatten(self, programs):
+        """Flatten program dicts into a set of run modes."""
+        run_modes = set()
+        for program in programs:
+            for course_code in program['course_codes']:
+                for run in course_code['run_modes']:
+                    course_key = CourseKey.from_string(run['course_key'])
+                    run_modes.add(
+                        RunMode(course_key, run['mode_slug'])
+                    )
+
+        return run_modes
+
+    def _load_usernames(self):
+        """Identify a subset of users who may be eligible for a program certificate.
+
+        This is done by finding users who have earned a certificate in at least one
+        program course code's run mode.
+        """
+        query = reduce(
+            lambda x, y: x | y,
+            [Q(course_id=r.course_key, mode=r.mode_slug) for r in self.run_modes]
+        )
+
+        # TODO: Filter further, by passing status?
+        username_dicts = GeneratedCertificate.eligible_certificates.filter(query).values('user__username').distinct()
+        self.usernames = [d['user__username'] for d in username_dicts]