feat: added archived topics in v3 api (#31443)

* feat: added archived topis in v3 api

* fix: resolved issue with failed test

* fix: updated functions docs

* feat: added test for util function

lms/djangoapps/discussion/rest_api/tests/test_utils.py

@@ -17,6 +17,7 @@ from lms.djangoapps.discussion.rest_api.utils import (
     get_course_ta_users_list,
     get_course_staff_users_list,
     get_moderator_users_list,
+    get_archived_topics
 )
 
 
@@ -71,3 +72,25 @@ class DiscussionAPIUtilsTestCase(ModuleStoreTestCase):
     def test_course_ta_users_list(self):
         ta_user_list = get_course_ta_users_list(self.course.id)
         assert len(ta_user_list) == 2
+
+    def test_get_archived_topics(self):
+        # Define some example inputs
+        filtered_topic_ids = ['t1', 't2', 't3', 't4']
+        topics = [
+            {'id': 't1', 'usage_key': 'u1', 'title': 'Topic 1'},
+            {'id': 't2', 'usage_key': None, 'title': 'Topic 2'},
+            {'id': 't3', 'usage_key': 'u3', 'title': 'Topic 3'},
+            {'id': 't4', 'usage_key': 'u4', 'title': 'Topic 4'},
+            {'id': 't5', 'usage_key': None, 'title': 'Topic 5'},
+        ]
+        expected_output = [
+            {'id': 't1', 'usage_key': 'u1', 'title': 'Topic 1'},
+            {'id': 't3', 'usage_key': 'u3', 'title': 'Topic 3'},
+            {'id': 't4', 'usage_key': 'u4', 'title': 'Topic 4'},
+        ]
+
+        # Call the function with the example inputs
+        output = get_archived_topics(filtered_topic_ids, topics)
+
+        # Assert that the output matches the expected output
+        assert output == expected_output

lms/djangoapps/discussion/rest_api/utils.py

@@ -1,6 +1,7 @@
 """
 Utils for discussion API.
 """
+from typing import List, Dict
 
 from django.contrib.auth.models import User  # lint-amnesty, pylint: disable=imported-auth-user
 from django.core.paginator import Paginator
@@ -92,7 +93,7 @@ def get_usernames_for_course(course_id, page_number, page_size):
             matched_users_count (int): count of matched users in course
             matched_users_pages (int): pages of matched users in course
     """
-    matched_users_in_course = User.objects.filter(courseenrollment__course_id=course_id,)\
+    matched_users_in_course = User.objects.filter(courseenrollment__course_id=course_id, ) \
         .order_by(Length('username').asc()).values_list('username', flat=True)
     if not matched_users_in_course:
         return '', 0, 0
@@ -240,15 +241,67 @@ def create_topics_v3_structure(blocks, topics):
             value['courseware'] = True
             courseware_topics.append(value)
             value['children'] = create_discussion_children_from_ids(
-                value['children'],
+                value.get('children', []),
                 blocks,
                 topics,
             )
             subsections = value.get('children')
             for subsection in subsections:
                 subsection['children'] = create_discussion_children_from_ids(
-                    subsection['children'],
+                    subsection.get('children', []),
                     blocks,
                     topics,
                 )
-    return non_courseware_topics + courseware_topics
+
+    structured_topics = non_courseware_topics + courseware_topics
+    topic_ids = get_topic_ids_from_topics(topics)
+
+    # Remove all topic ids that are contained in the structured topics
+    for chapter in structured_topics:
+        for sequential in chapter.get('children', []):
+            for item in sequential['children']:
+                topic_ids.remove(item['id'])
+
+    archived_topics = {
+        'id': "archived",
+        'children': get_archived_topics(topic_ids, topics)
+    }
+    if archived_topics['children']:
+        structured_topics.append(archived_topics)
+
+    return structured_topics
+
+
+def get_topic_ids_from_topics(topics: List[Dict[str, str]]) -> List[str]:
+    """
+    This function takes a list of topics and returns a list of the topic ids.
+
+    Args:
+    - topics (List[Dict[str, str]]): A list of topic dictionaries. Each dictionary should have an 'id' field.
+
+    Returns:
+    - A list of topic ids, extracted from the input list of topics.
+    """
+    return [topic['id'] for topic in topics]
+
+
+def get_archived_topics(filtered_topic_ids: List[str], topics: List[Dict[str, str]]) -> List[Dict[str, str]]:
+    """
+    This function takes a list of topic ids and a list of topics, and returns the list of archived topics.
+
+    A topic is considered archived if it has a non-null `usage_key` field.
+
+    Args:
+    - filtered_topic_ids (List[str]): A list of topic ids to filter on.
+    - topics (List[Dict[str, str]]): A list of topic dictionaries.
+    - Each dictionary should have a 'id' and a 'usage_key' field.
+
+    Returns:
+    - A list of archived topic dictionaries, with the same format as the input topics.
+    """
+    archived_topics = []
+    for topic_id in filtered_topic_ids:
+        for topic in topics:
+            if topic['id'] == topic_id and topic['usage_key'] is not None:
+                archived_topics.append(topic)
+    return archived_topics