fix(sample_project): fix countdown

Closes: #992

sample_project/templatetags/sample_project.py

@@ -1,4 +1,4 @@
-import datetime
+from datetime import datetime, time, date, timedelta, UTC
 import pathlib
 from django import template
 
@@ -12,6 +12,16 @@ def password():
 
 @register.simple_tag
 def teardown():
-    date = datetime.datetime.fromisoformat(pathlib.Path("/tmp/startup.txt").read_text())
-    until = date + datetime.timedelta(hours=6)
-    return until
+    init_date = datetime.combine(date.today(), time(0, 30, 0), tzinfo=UTC)
+    # create timetsamps for today
+    timestamps = [
+        init_date,
+        init_date.replace(hour=6),
+        init_date.replace(hour=12),
+        init_date.replace(hour=18),
+    ]
+    # create timestamps for tomorrow
+    timestamps += list(map(lambda x: x + timedelta(hours=24), timestamps))
+    # filter timestamps that are after now
+    timestamps = list(filter(lambda x: x > datetime.now(UTC), timestamps))
+    return timestamps[0]