Invoice: add "credit note" type and add invoice cancellation admin action

demo/example/sample_plans/migrations/0003_billinginfo_created_billinginfo_updated_at_and_more.py

@@ -0,0 +1,46 @@
+# Generated by Django 5.2.2 on 2025-06-19 12:00
+
+import django.db.models.deletion
+import django_countries.fields
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("sample_plans", "0002_billinginfo_created_billinginfo_updated_at_and_more"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="invoice",
+            name="cancellation_reason",
+            field=models.TextField(blank=True, verbose_name="Cancellation reason"),
+        ),
+        migrations.AddField(
+            model_name="invoice",
+            name="credit_note_for",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                related_name="issued_credit_notes",
+                to="sample_plans.invoice",
+                verbose_name="Credit note for",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="invoice",
+            name="type",
+            field=models.IntegerField(
+                choices=[
+                    (1, "Invoice"),
+                    (2, "Invoice Duplicate"),
+                    (3, "Order confirmation"),
+                    (4, "Credit note"),
+                ],
+                db_index=True,
+                default=1,
+            ),
+        ),
+    ]

plans/admin.py

@@ -2,11 +2,15 @@
 
 from django.contrib import admin
 from django.contrib.auth import get_user_model
+from django.http import HttpResponseRedirect
+from django.template.response import TemplateResponse
 from django.urls import reverse
 from django.utils.html import format_html
 from django.utils.translation import gettext_lazy as _
 from ordered_model.admin import OrderedModelAdmin
 
+from .forms import PartialCreditNoteForm
+
 from plans.base.models import (
     AbstractBillingInfo,
     AbstractInvoice,
@@ -211,6 +215,80 @@ def queryset(self, request):
         )
 
 
+def cancel_selected_invoices(modeladmin, request, queryset):
+    for invoice in queryset:
+        try:
+            invoice.cancel_invoice()
+            modeladmin.message_user(
+                request, f"Invoice {invoice.full_number} cancelled successfully."
+            )
+        except Exception as e:
+            modeladmin.message_user(
+                request, f"Could not cancel {invoice.full_number}: {e}", level="ERROR"
+            )
+
+
+cancel_selected_invoices.short_description = _("Cancel and issue credit note")
+
+
+def create_partial_credit_note(modeladmin, request, queryset):
+    """Create partial credit notes with custom amounts"""
+    if queryset.count() != 1:
+        modeladmin.message_user(
+            request,
+            "Please select exactly one invoice to create a partial credit note.",
+            level="ERROR",
+        )
+        return
+
+    invoice = queryset.first()
+    if invoice.type != invoice.INVOICE_TYPES.INVOICE:
+        modeladmin.message_user(
+            request,
+            "Only regular invoices can have partial credit notes.",
+            level="ERROR",
+        )
+        return
+
+    if request.method == "POST" and "apply" in request.POST:
+        form = PartialCreditNoteForm(request.POST)
+        if form.is_valid():
+            credit_note = invoice.create_partial_credit_note(
+                form.cleaned_data["net_amount"],
+                form.cleaned_data["tax_amount"],
+                form.cleaned_data["reason"],
+            )
+            modeladmin.message_user(
+                request,
+                "Partial credit note %s created successfully for invoice %s."
+                % (credit_note.full_number, invoice.full_number),
+            )
+            return HttpResponseRedirect(reverse("admin:plans_invoice_changelist"))
+    else:
+        # Initialize form with default values from invoice
+        initial_data = {
+            "net_amount": invoice.total_net,
+            "tax_amount": invoice.tax_total,
+            "reason": "",
+        }
+        form = PartialCreditNoteForm(initial=initial_data)
+
+    context = {
+        "title": "Create Partial Credit Note for Invoice %s" % invoice.full_number,
+        "invoice": invoice,
+        "opts": modeladmin.model._meta,
+        "has_view_permission": modeladmin.has_view_permission(request),
+        "form": form,
+    }
+
+    return TemplateResponse(
+        request, "admin/plans/invoice/partial_credit_note_form.html", context
+    )
+
+
+create_partial_credit_note.short_description = _("Create partial credit note")
+
+
 class InvoiceAdmin(admin.ModelAdmin):
     search_fields = ("full_number", "buyer_tax_number", "user__username", "user__email")
     list_filter = (
@@ -231,10 +309,103 @@ class InvoiceAdmin(admin.ModelAdmin):
         "buyer_city",
         "buyer_tax_number",
     )
-    readonly_fields = ("created", "updated_at")
+    readonly_fields = (
+        "created",
+        "updated_at",
+        "full_number",
+        "number",
+        "total_net",
+        "tax_total",
+        "total",
+    )
     list_display_links = list_display
     list_select_related = True
-    raw_id_fields = ("user", "order")
+    raw_id_fields = ("user", "order", "credit_note_for")
+    actions = (cancel_selected_invoices, create_partial_credit_note)
+    fieldsets = (
+        (
+            _("Invoice Details"),
+            {
+                "fields": (
+                    "type",
+                    "full_number",
+                    "number",
+                    "user",
+                    "order",
+                    "credit_note_for",
+                    "cancellation_reason",
+                )
+            },
+        ),
+        (
+            _("Dates"),
+            {
+                "fields": (
+                    "issued",
+                    "selling_date",
+                    "payment_date",
+                    "issued_duplicate",
+                    "created",
+                    "updated_at",
+                )
+            },
+        ),
+        (
+            _("Billing Details"),
+            {
+                "fields": (
+                    "item_description",
+                    "quantity",
+                    "unit_price_net",
+                    "tax",
+                    "rebate",
+                    "currency",
+                    "total_net",
+                    "tax_total",
+                    "total",
+                )
+            },
+        ),
+        (
+            _("Buyer Details"),
+            {
+                "fields": (
+                    "buyer_name",
+                    "buyer_street",
+                    "buyer_zipcode",
+                    "buyer_city",
+                    "buyer_country",
+                    "buyer_tax_number",
+                )
+            },
+        ),
+        (
+            _("Shipping Details"),
+            {
+                "fields": (
+                    "require_shipment",
+                    "shipping_name",
+                    "shipping_street",
+                    "shipping_zipcode",
+                    "shipping_city",
+                    "shipping_country",
+                )
+            },
+        ),
+        (
+            _("Issuer Details"),
+            {
+                "fields": (
+                    "issuer_name",
+                    "issuer_street",
+                    "issuer_zipcode",
+                    "issuer_city",
+                    "issuer_country",
+                    "issuer_tax_number",
+                )
+            },
+        ),
+    )
 
 
 class RecurringPlanInline(admin.StackedInline):