Added filter bewaartermijn in Django admin

app/apps/cases/admin.py

@@ -1,4 +1,4 @@
-from datetime import date
+from datetime import date, timedelta
 
 from apps.cases.models import (
     Advertisement,
@@ -20,6 +20,9 @@
 from django import forms
 from django.contrib import admin
 from django.contrib.contenttypes.models import ContentType
+from django.db.models import Exists, OuterRef
+from django.utils import timezone
+from django.utils.translation import gettext_lazy as _
 
 
 class LabelThemeModelChoiceField(forms.ModelChoiceField):
@@ -109,6 +112,43 @@ class CaseDocumentAdmin(admin.ModelAdmin):
     search_fields = ("case__id",)
 
 
+class BewaartermijnFilter(admin.SimpleListFilter):
+    title = _("Verlopen Bewaartermijnen")
+    parameter_name = "bewaartermijn"
+
+    def lookups(self, request, model_admin):
+        """Options that will appear in the filter dropdown."""
+        return (
+            ("toezicht_5_jaar", _("Toezicht bewaartermijn (5 jaar)")),
+            ("handhaving_10_jaar", _("Handhaving bewaartermijn (10 jaar)")),
+        )
+
+    def queryset(self, request, queryset):
+        """Filter the queryset based on the selected filter option."""
+        if self.value() == "toezicht_5_jaar":
+            # Filter cases that ended more than 5 years ago and have NO status HANDHAVING
+            five_years_ago = timezone.now().date() - timedelta(days=5 * 365)
+            return queryset.exclude(
+                Exists(
+                    CaseState.objects.filter(
+                        case=OuterRef("pk"), status=CaseState.CaseStateChoice.HANDHAVING
+                    )
+                )
+            ).filter(end_date__lt=five_years_ago)
+        elif self.value() == "handhaving_10_jaar":
+            # Filter cases that ended more than 10 years ago and have a status HANDHAVING
+            ten_years_ago = timezone.now().date() - timedelta(days=10 * 365)
+            return queryset.filter(
+                Exists(
+                    CaseState.objects.filter(
+                        case=OuterRef("pk"), status=CaseState.CaseStateChoice.HANDHAVING
+                    )
+                ),
+                end_date__lt=ten_years_ago,
+            )
+        return queryset
+
+
 @admin.register(Case)
 class CaseAdmin(admin.ModelAdmin):
     form = CaseAdminForm
@@ -122,6 +162,7 @@ class CaseAdmin(admin.ModelAdmin):
     )
     list_filter = (
         "theme",
+        BewaartermijnFilter,
         "start_date",
         "end_date",
         "address__housing_corporation",