feat(apps/contests): improve the admin page

apps/contests/admin.py

@@ -1,21 +1,47 @@
 from typing import TYPE_CHECKING
 
 from django.contrib.admin import ModelAdmin, register
+from django.forms import (
+    CharField,
+    ModelForm,
+    ModelMultipleChoiceField,
+    Textarea,
+)
 from django.utils.translation import gettext_lazy as _
 
 from apps.contests.models import Contest
+from apps.users.models import User
 
 if TYPE_CHECKING:
     ContestAdminBase = ModelAdmin[Contest]
+    ContestModelFormBase = ModelForm[Contest]
 else:
     ContestAdminBase = ModelAdmin
+    ContestModelFormBase = ModelForm
+
+
+class ContestModelForm(ContestModelFormBase):
+    description = CharField(widget=Textarea(attrs={"rows": 14, "cols": 80}))
+    users = ModelMultipleChoiceField(
+        queryset=User.objects.all(), required=False
+    )
+
+    class Meta:
+        model = Contest
+        fields = "__all__"
 
 
 @register(Contest)
 class ContestAdmin(ContestAdminBase):
-    list_display = ("title", "start_time", "status")
+    form = ContestModelForm
+
+    list_display = ("title", "start_time", "end_time", "status")
     list_filter = ("start_time", "end_time")
+
     fieldsets = [
         (_("General"), {"fields": ("title", "description")}),
-        (_("Other"), {"fields": ("start_time", "end_time", "users")}),
+        (
+            _("Other"),
+            {"fields": ("start_time", "end_time", "users", "cancelled")},
+        ),
     ]