admin/overview: Show some statistics

admin/overview.html

@@ -3,6 +3,10 @@
 {% block content %}
   <h3>Welcome, {{ username }}!</h3>
 
+  <p>
+    There {% if session_count == 1 %}is{% else %}are{% end %} currently <i>{{ session_count }}</i> active session{% if session_count != 1 %}s{% end %} with <i>{{ total_player_count }}</i> active player{% if total_player_count != 1 %}s{% end %}.
+  </p>
+
   Actions:
   <ul>
     <li>

admin/overview.py

@@ -2,10 +2,25 @@
 
 from admin.base import AdminHandler
 
+import api
+
 # pylint: disable=W0223
 class Handler(AdminHandler):
     """Handle admin overview"""
 
+    def template_args(self):
+        """Additional template arguments"""
+
+        total_player_count = 0
+
+        for secret in api.SESSIONS:
+            total_player_count += api.SESSIONS[secret]['player_count']
+
+        return {
+            "session_count": len(api.SESSIONS),
+            "total_player_count": total_player_count
+        }
+
     def view(self):
         """View to display"""
         return "overview"