feat: adds ability to disable posting in discussions indefinitely (#32171)

* feat: adds ability to disable posting in discussions indefinitely

* test: fixed ffailing test cases

* test: added new model field in test cases

* refactor: removes unnecessary migrations

* refactor: removed previous migrations and adds new field in discussions api

* refactor: added docstring and changed method name

---------

Co-authored-by: ayesha waris <73840786+ayeshoali@users.noreply.github.com>

lms/djangoapps/discussion/rest_api/api.py

@@ -40,7 +40,12 @@ from lms.djangoapps.courseware.exceptions import CourseAccessRedirect
 from lms.djangoapps.discussion.toggles import ENABLE_DISCUSSIONS_MFE, ENABLE_LEARNERS_TAB_IN_DISCUSSIONS_MFE
 from lms.djangoapps.discussion.toggles_utils import reported_content_email_notification_enabled
 from lms.djangoapps.discussion.views import is_privileged_user
-from openedx.core.djangoapps.discussions.models import DiscussionsConfiguration, DiscussionTopicLink, Provider
+from openedx.core.djangoapps.discussions.models import (
+    DiscussionsConfiguration,
+    DiscussionTopicLink,
+    Provider,
+    PostingRestriction
+)
 from openedx.core.djangoapps.discussions.utils import get_accessible_discussion_xblocks
 from openedx.core.djangoapps.django_comment_common import comment_client
 from openedx.core.djangoapps.django_comment_common.comment_client.comment import Comment
@@ -319,14 +324,38 @@ def get_course(request, course_key):
         """
         return dt.isoformat().replace('+00:00', 'Z')
 
+    def is_posting_allowed(posting_restrictions, blackout_schedules):
+        """
+        Check if posting is allowed based on the given posting restrictions and blackout schedules.
+
+        Args:
+            posting_restrictions (str): Values would be  "disabled", "scheduled" or "enabled".
+            blackout_schedules (List[Dict[str, datetime]]): The list of blackout schedules
+
+        Returns:
+            bool: True if posting is allowed, False otherwise.
+        """
+        now = datetime.now(UTC)
+        if posting_restrictions == PostingRestriction.DISABLED:
+            return True
+        elif posting_restrictions == PostingRestriction.SCHEDULED:
+            return not any(schedule["start"] <= now <= schedule["end"] for schedule in blackout_schedules)
+        else:
+            return False
+
     course = _get_course(course_key, request.user)
     user_roles = get_user_role_names(request.user, course_key)
     course_config = DiscussionsConfiguration.get(course_key)
     EDIT_REASON_CODES = getattr(settings, "DISCUSSION_MODERATION_EDIT_REASON_CODES", {})
     CLOSE_REASON_CODES = getattr(settings, "DISCUSSION_MODERATION_CLOSE_REASON_CODES", {})
+    is_posting_enabled = is_posting_allowed(
+        course_config.posting_restrictions,
+        course.get_discussion_blackout_datetimes()
+    )
 
     return {
         "id": str(course_key),
+        "is_posting_enabled": is_posting_enabled,
         "blackouts": [
             {
                 "start": _format_datetime(blackout["start"]),

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

@@ -190,6 +190,7 @@ class GetCourseTest(ForumsEnableMixin, UrlResetMixin, SharedModuleStoreTestCase)
     def test_basic(self):
         assert get_course(self.request, self.course.id) == {
             'id': str(self.course.id),
+            'is_posting_enabled': True,
             'blackouts': [],
             'thread_list_url': 'http://testserver/api/discussion/v1/threads/?course_id=course-v1%3Ax%2By%2Bz',
             'following_thread_list_url':

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

@@ -517,6 +517,7 @@ class CourseViewTest(DiscussionAPIViewTestMixin, ModuleStoreTestCase):
             200,
             {
                 "id": str(self.course.id),
+                "is_posting_enabled": True,
                 "blackouts": [],
                 "thread_list_url": "http://testserver/api/discussion/v1/threads/?course_id=course-v1%3Ax%2By%2Bz",
                 "following_thread_list_url": (