Add prerequisites handling to CaseCollection and implement user access checks

atlas/templates/atlas/collection_case_view_take.html

@@ -404,6 +404,14 @@
                     }
                 }
 
+                // If time has already elapsed when the page loads, lock the question and do not autosubmit.
+                if (remaining <= 0) {
+                    console.debug('Timer: time already expired on load, locking without autosubmit');
+                    lockQuestion();
+                    $timer.text(formatTime(0));
+                    return;
+                }
+
                 function formatTime(s) {
                     var mins = Math.floor(s / 60);
                     var secs = s % 60;

atlas/templates/atlas/prerequisite_required.html

@@ -0,0 +1,14 @@
+{% extends 'atlas/base.html' %}
+
+{% block content %}
+  <h2>Collection requires completion of another collection</h2>
+  <p>{{ message }}</p>
+  {% if prereq %}
+    <p>
+      You must complete the collection: <a href="{% url 'atlas:collection_take_start' prereq.pk %}">{{ prereq.name }}</a>
+    </p>
+  {% endif %}
+  <p>
+    If you think this is an error, contact the course administrator.
+  </p>
+{% endblock %}