feat: add util method in edx-val for listing transcript_languages for…

… a course

edxval/api.py

@@ -733,6 +733,29 @@ def get_videos_for_course(course_id, sort_field=None, sort_dir=SortDirection.asc
     )
 
 
+def get_transcript_languages(course_id, provider_type):
+    """
+    Returns a list of languages for which transcripts are available for a course
+
+    Args:
+        course_id (str): course id
+        provider_type (str): transcript provider type
+
+    Returns:
+        (list): A list of language codes
+    """
+    transcript_languages = set()
+    video_transcripts = VideoTranscript.objects.filter(
+        video__edx_video_id__in=CourseVideo.objects.filter(
+            course_id=course_id
+        ).values_list("video__edx_video_id", flat=True)
+    ).select_related("video", "transcript", "transcript__file")
+    for transcript in video_transcripts:
+        if transcript.provider == provider_type:
+            transcript_languages.add(transcript.language_code)
+    return list(transcript_languages)
+
+
 def get_course_videos_qset(course_id):
     """
     Get a QuerySet of CourseVideos for a given course.