Enable datetime localization for client

- Detect and store client timezone in cookies
- Add UserTimezoneMiddleware to activate localization based on cookies

Signed-off-by: Keshav Priyadarshi <git@keshav.space>

Author: keshav-space

vulnerabilities/middleware/timezone.py

@@ -0,0 +1,30 @@
+#
+# Copyright (c) nexB Inc. and others. All rights reserved.
+# VulnerableCode is a trademark of nexB Inc.
+# SPDX-License-Identifier: Apache-2.0
+# See http://www.apache.org/licenses/LICENSE-2.0 for the license text.
+# See https://github.com/aboutcode-org/vulnerablecode for support or download.
+# See https://aboutcode.org for more information about nexB OSS projects.
+#
+
+import zoneinfo
+
+from django.utils import timezone
+
+
+class UserTimezoneMiddleware:
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        try:
+            # Activate local timezone for user using cookies
+            tzname = request.COOKIES.get("user_timezone")
+            if tzname:
+                timezone.activate(zoneinfo.ZoneInfo(tzname))
+            else:
+                timezone.deactivate()
+        except Exception as e:
+            timezone.deactivate()
+
+        return self.get_response(request)

vulnerabilities/templates/base.html

@@ -22,7 +22,13 @@
         {% block content %}{% endblock %}
         {% include "footer.html" %}
     </div>
-
+    <script>
+        // Since django can not determine the client’s time zone automatically.
+        // Store client's timezone in cookies to enable localization.
+        // https://docs.djangoproject.com/en/5.1/topics/i18n/timezones/#selecting-the-current-time-zone
+        const currentTimeZone = Intl.DateTimeFormat().resolvedOptions().timeZone;
+        document.cookie = "user_timezone=" + currentTimeZone;
+    </script>
     {% block scripts %}
     {% endblock %}
 </body>

vulnerablecode/settings.py

@@ -102,6 +102,7 @@
     "django.contrib.messages.middleware.MessageMiddleware",
     "django.middleware.clickjacking.XFrameOptionsMiddleware",
     "vulnerabilities.middleware.ban_user_agent.BanUserAgent",
+    "vulnerabilities.middleware.timezone.UserTimezoneMiddleware",
 )
 
 ROOT_URLCONF = "vulnerablecode.urls"