Add config switch + signal for generating program certs.

ECOM-3523

openedx/core/djangoapps/programs/tasks.py

@@ -0,0 +1,55 @@
+"""
+This file contains celery tasks for programs-related functionality.
+"""
+
+from celery import task
+from celery.utils.log import get_task_logger  # pylint: disable=no-name-in-module, import-error
+
+from lms.djangoapps.certificates.api import get_certificates_for_user
+
+LOGGER = get_task_logger(__name__)
+
+
+@task
+def award_program_certificates(username):
+    """
+    This task is designed to be called whenever a user's completion status
+    changes with respect to one or more courses (primarily, when a course
+    certificate is awarded).
+
+    It will consult with a variety of APIs to determine whether or not the
+    specified user should be awarded a certificate in one or more programs, and
+    use the credentials service to create said certificates if so.
+
+    This task may also be invoked independently of any course completion status
+    change - for example, to backpopulate missing program credentials for a
+    user.
+
+    TODO: this is shelled out and incomplete for now.
+    """
+
+    # fetch the set of all course runs for which the user has earned a certificate
+    LOGGER.debug('fetching all completed courses for user %s', username)
+    user_certs = get_certificates_for_user(username)
+    course_certs = [
+        {'course_id': uc['course_id'], 'mode': uc['mode']}
+        for uc in user_certs
+        if uc['status'] in ('downloadable', 'generating')
+    ]
+
+    # invoke the Programs API completion check endpoint to identify any programs
+    # that are satisfied by these course completions
+    LOGGER.debug('determining completed programs for courses: %r', course_certs)
+    program_ids = []  # TODO
+
+    # determine which program certificates the user has already been awarded, if
+    # any, and remove those, since they already exist.
+    LOGGER.debug('fetching existing program certificates for %s', username)
+    existing_program_ids = []  # TODO
+    new_program_ids = list(set(program_ids) - set(existing_program_ids))
+
+    # generate a new certificate for each of the remaining programs.
+    LOGGER.debug('generating new program certificates for %s in programs: %r', username, new_program_ids)
+    for program_id in new_program_ids:
+        LOGGER.debug('calling credentials service to issue certificate for user %s in program %s', username, program_id)
+        # TODO