feat(AU-1950): Match video CC to unit translation language (#34667)

* feat(AU-1950): Match video CC to unit translation language

* feat(AU-1950): Update doc string

* fix: make dest_lang optional param

xmodule/video_block/transcripts_utils.py

@@ -856,15 +856,19 @@ class VideoTranscriptsMixin:
         # to clean redundant language codes.
         return list(set(translations))
 
-    def get_default_transcript_language(self, transcripts):
+    def get_default_transcript_language(self, transcripts, dest_lang=None):
         """
         Returns the default transcript language for this video block.
 
         Args:
             transcripts (dict): A dict with all transcripts and a sub.
+            dest_lang (unicode): language coming from unit translation language selector.
         """
         sub, other_lang = transcripts["sub"], transcripts["transcripts"]
-        if self.transcript_language in other_lang:
+
+        if dest_lang and dest_lang in other_lang.keys():
+            transcript_language = dest_lang
+        elif self.transcript_language in other_lang:
             transcript_language = self.transcript_language
         elif sub:
             transcript_language = 'en'

xmodule/video_block/video_block.py

@@ -159,7 +159,7 @@ class VideoBlock(
 
     uses_xmodule_styles_setup = True
 
-    def get_transcripts_for_student(self, transcripts):
+    def get_transcripts_for_student(self, transcripts, dest_lang=None):
         """Return transcript information necessary for rendering the XModule student view.
         This is more or less a direct extraction from `get_html`.
 
@@ -180,7 +180,7 @@ class VideoBlock(
             elif sub or other_lang:
                 track_url = self.runtime.handler_url(self, 'transcript', 'download').rstrip('/?')
 
-        transcript_language = self.get_default_transcript_language(transcripts)
+        transcript_language = self.get_default_transcript_language(transcripts, dest_lang)
         native_languages = {lang: label for lang, label in settings.LANGUAGES if len(lang) == 2}
         languages = {
             lang: native_languages.get(lang, display)
@@ -237,11 +237,11 @@ class VideoBlock(
 
         return False
 
-    def student_view(self, _context):
+    def student_view(self, context):
         """
         Return the student view.
         """
-        fragment = Fragment(self.get_html())
+        fragment = Fragment(self.get_html(context=context))
         add_sass_to_fragment(fragment, 'VideoBlockDisplay.scss')
         add_webpack_js_to_fragment(fragment, 'VideoBlockDisplay')
         shim_xmodule_js(fragment, 'Video')
@@ -371,7 +371,10 @@ class VideoBlock(
                 download_video_link = next((url for url in self.html5_sources if not url.endswith('.m3u8')), None)
 
         transcripts = self.get_transcripts_info()
-        track_url, transcript_language, sorted_languages = self.get_transcripts_for_student(transcripts=transcripts)
+        track_url, transcript_language, sorted_languages = self.get_transcripts_for_student(
+            transcripts=transcripts,
+            dest_lang=context.get("dest_lang")
+        )
 
         cdn_eval = False
         cdn_exp_group = None

xmodule/video_block/video_handlers.py

@@ -330,7 +330,6 @@ class VideoStudentViewHandlers:
                 return Response(status=404)
 
             if language != self.transcript_language:
-
                 self.transcript_language = language
 
             try: