fix: display empty revision and reduce catalog queries (#3435)

Author: arslanashraf7

cms/templates/catalog_page.html

@@ -289,10 +289,10 @@ <h1>{{ site_name }}—Professional Development, the MIT Way</h1>
                         aria-labelledby="programs-tab"
                       >
                         {% endif %}
-                        <h1>PROGRAMS</h1>
                         {% if not program_pages %}
                         {% include "partials/catalog_empty.html" %}
                         {% else %}
+                        <h1>PROGRAMS</h1>
                         {% for program_page in program_pages %}
                         {% include "partials/catalog_card.html" with courseware_page=program_page object_type="program" tab="program" %}
                         {% endfor %}
@@ -314,10 +314,10 @@ <h1>PROGRAMS</h1>
                           aria-labelledby="courses-tab"
                         >
                           {% endif %}
-                          <h1>COURSES</h1>
                           {% if not course_pages %}
                           {% include "partials/catalog_empty.html" %}
                           {% else %}
+                          <h1>COURSES</h1>
                           {% for course_page in course_pages %}
                           {% include "partials/catalog_card.html" with courseware_page=course_page object_type="course" tab="course" %}
                           {% endfor %}

courses/utils.py

@@ -351,19 +351,13 @@ def get_catalog_languages():
     """
     Returns the languages that are associated with courses or programs visible in the catalog
     """
-
+    # We will not add any filters for programs here because the visibility of the programs on catalog
+    # page depends on the visibility of the courses in the program. Also, We expect the program and
+    # course languages to be the same. So, we will only consider the course languages here.
     course_languages = (
         CourseLanguage.objects.filter(
             Q(get_catalog_course_filter("coursepage__"))
-            | Q(
-                get_catalog_course_filter("programpage__program__courses__coursepage__")
-            )
-            | Q(get_catalog_course_filter("externalcoursepage__"))
-            | Q(
-                get_catalog_course_filter(
-                    "externalprogrampage__program__courses__externalcoursepage__"
-                )
-            ),
+            | Q(get_catalog_course_filter("externalcoursepage__")),
             is_active=True,
         )
         .distinct()