feat: User timezone

core/middleware.py

@@ -1,3 +1,4 @@
+import zoneinfo
 from typing import Callable
 
 from django.core.cache import cache
@@ -25,3 +26,20 @@ def __call__(self, request: HttpRequest):
             up.last_seen = timezone.now()
             up.save(update_fields=("last_seen",))
         return response
+
+
+class TimezoneMiddleware:
+    def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]):
+        self.get_response = get_response
+
+    def __call__(self, request: HttpRequest):
+        if request.user.is_authenticated:
+            up = UserProfile.objects.filter(user=request.user).only("timezone").first()
+            if up and up.timezone:
+                try:
+                    timezone.activate(zoneinfo.ZoneInfo(up.timezone))
+                except zoneinfo.ZoneInfoNotFoundError:
+                    pass  # Fall back to default timezone
+        response = self.get_response(request)
+        timezone.deactivate()
+        return response

core/migrations/0065_userprofile_timezone.py

@@ -0,0 +1,26 @@
+# Generated by Django 5.2.12 on 2026-03-05 23:37
+
+from django.db import migrations, models
+
+import core.models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("core", "0064_userprofile_disable_hints"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="userprofile",
+            name="timezone",
+            field=models.CharField(
+                blank=True,
+                default="",
+                help_text="Your local time zone for displaying timestamps. Leave blank to use server time (America/New_York).",
+                max_length=63,
+                validators=[core.models.validate_timezone],
+                verbose_name="Time zone",
+            ),
+        ),
+    ]

core/models.py

@@ -2,9 +2,11 @@
 
 import datetime
 import os
+import zoneinfo
 from typing import Callable
 
 from django.contrib.auth import get_user_model
+from django.core.exceptions import ValidationError
 from django.db import models
 from django.db.models.manager import BaseManager
 from django.urls import reverse
@@ -14,6 +16,14 @@
 # Create your models here.
 
 
+def validate_timezone(value: str) -> None:
+    if value:  # blank is allowed
+        try:
+            zoneinfo.ZoneInfo(value)
+        except zoneinfo.ZoneInfoNotFoundError:
+            raise ValidationError(f"{value} is not a valid timezone")
+
+
 class Semester(models.Model):
     """Represents an academic semester/year/etc, e.g. "Fall 2017"
     or "Year III"."""
@@ -298,6 +308,14 @@ class UserProfile(models.Model):
         help_text="Hide all hints from the problem archive (ARCH).",
         default=False,
     )
+    timezone = models.CharField(
+        max_length=63,
+        blank=True,
+        default="",
+        verbose_name="Time zone",
+        help_text="Your local time zone for displaying timestamps. Leave blank to use server time (America/New_York).",
+        validators=[validate_timezone],
+    )
 
     email_on_announcement = models.BooleanField(
         verbose_name="Receive emails for announcements",

core/templates/core/userprofile_form.html

@@ -32,7 +32,125 @@ <h1>Display settings</h1>
     <div class="section">
       <h1>Advanced settings</h1>
       {% for field in advanced_fields %}{{ field|as_crispy_field }}{% endfor %}
+      <div class="mb-2">
+        <label for="timezone-search" class="form-label">Search time zone</label>
+        <input type="text"
+               class="form-control"
+               id="timezone-search"
+               placeholder="Type to filter, e.g. Seoul or Korea" />
+      </div>
+      {{ timezone_field|as_crispy_field }}
       <button type="submit" class="btn btn-success">Update settings</button>
+      <div id="timezone-suggestion"
+           class="alert alert-info mt-2"
+           style="display: none">
+        Detected timezone: <strong id="detected-tz"></strong>
+        <button type="button"
+                class="btn btn-sm btn-primary ms-2"
+                id="use-detected-tz">Use this timezone</button>
+        <button type="button"
+                class="btn-close float-end"
+                aria-label="Close"
+                id="dismiss-tz-suggestion"></button>
+      </div>
     </div>
+    {{ timezone_extra_aliases|json_script:"timezone-extra-aliases" }}
   </form>
 {% endblock layout-content %}
+{% block scripts %}
+  <script>
+      // Show timezone suggestion if field is empty
+      document.addEventListener('DOMContentLoaded', function() {
+          const timezoneField = document.getElementById('id_timezone');
+          const timezoneSearch = document.getElementById('timezone-search');
+          const suggestionDiv = document.getElementById('timezone-suggestion');
+          const detectedTzSpan = document.getElementById('detected-tz');
+          const useButton = document.getElementById('use-detected-tz');
+          const dismissButton = document.getElementById('dismiss-tz-suggestion');
+          const aliasesScript = document.getElementById('timezone-extra-aliases');
+          let aliasesByTimezone = {};
+          if (aliasesScript) {
+              aliasesByTimezone = JSON.parse(aliasesScript.textContent);
+          }
+
+          function getTimezoneNameForSearch(timezoneName) {
+              if (!timezoneName) {
+                  return '';
+              }
+              try {
+                  const parts = new Intl.DateTimeFormat('en-US', {
+                      timeZone: timezoneName,
+                      timeZoneName: 'longGeneric',
+                  }).formatToParts(new Date());
+                  const zonePart = parts.find(function(part) {
+                      return part.type === 'timeZoneName';
+                  });
+                  return zonePart ? zonePart.value : '';
+              } catch (error) {
+                  return '';
+              }
+          }
+
+          let allOptions = [];
+          if (timezoneField) {
+              allOptions = Array.from(timezoneField.options).map(function(opt) {
+                  const aliasText = (aliasesByTimezone[opt.value] || []).join(' ');
+                  const zoneNameText = getTimezoneNameForSearch(opt.value);
+                  return {
+                      value: opt.value,
+                      label: opt.textContent,
+                      searchText: (opt.textContent + ' ' + zoneNameText + ' ' + aliasText).toLowerCase()
+                  };
+              });
+          }
+
+          if (timezoneSearch && timezoneField) {
+              timezoneSearch.addEventListener('input', function() {
+                  const query = timezoneSearch.value.toLowerCase().trim();
+                  const selectedValue = timezoneField.value;
+                  const filtered = allOptions.filter(function(opt) {
+                      if (!query) {
+                          return true;
+                      }
+                      return opt.searchText.includes(query);
+                  });
+                  timezoneField.innerHTML = '';
+                  filtered.forEach(function(opt) {
+                      const option = document.createElement('option');
+                      option.value = opt.value;
+                      option.textContent = opt.label;
+                      timezoneField.appendChild(option);
+                  });
+                  if (filtered.some(function(opt) {
+                          return opt.value === selectedValue;
+                      })) {
+                      timezoneField.value = selectedValue;
+                  } else if (filtered.length > 0) {
+                      timezoneField.selectedIndex = 0;
+                  }
+              });
+          }
+
+          if (timezoneField && !timezoneField.value && suggestionDiv) {
+              try {
+                  const detectedTimezone = Intl.DateTimeFormat().resolvedOptions().timeZone;
+                  if (detectedTimezone) {
+                      detectedTzSpan.textContent = detectedTimezone;
+                      suggestionDiv.style.display = 'block';
+
+                      useButton.addEventListener('click', function() {
+                          timezoneField.value = detectedTimezone;
+                          suggestionDiv.style.display = 'none';
+                      });
+
+                      dismissButton.addEventListener('click', function() {
+                          suggestionDiv.style.display = 'none';
+                      });
+                  }
+              } catch (error) {
+                  // Fail silently if auto-detection isn't available.
+              }
+          }
+      });
+  </script>
+{% endblock scripts %}