Implement voucher per event and for all events of an organizer: apply voucher in billing setting (#488)

* Apply voucher

* Add migration file, apply voucher for invoice

* Add pydantic model, minor refactor

* Fix spelling

* Add None case for validation

* Fix space

* Add pydantic req, edit validation error

* Add status paid for 0 ticket_fee invoice

* Update migration file, invoice billing model

* Change pdf format

* Add missing colon

* Resolve conversations

Author: HungNguyen-tma

src/pretix/base/migrations/0007_billinginvoice_final_ticket_fee_and_more.py

@@ -0,0 +1,39 @@
+# Generated by Django 5.1.4 on 2024-12-26 08:14
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0006_create_invoice_voucher'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='billinginvoice',
+            name='final_ticket_fee',
+            field=models.DecimalField(decimal_places=2, default=0, max_digits=10),
+        ),
+        migrations.AddField(
+            model_name='billinginvoice',
+            name='voucher_discount',
+            field=models.DecimalField(decimal_places=2, default=0, max_digits=10),
+        ),
+        migrations.AddField(
+            model_name='organizerbillingmodel',
+            name='invoice_voucher',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.CASCADE, related_name='billing', to='pretixbase.invoicevoucher'),
+        ),
+        migrations.AddField(
+            model_name='billinginvoice',
+            name='voucher_price_mode',
+            field=models.CharField(max_length=20, null=True),
+        ),
+        migrations.AddField(
+            model_name='billinginvoice',
+            name='voucher_value',
+            field=models.DecimalField(decimal_places=2, default=0, max_digits=10),
+        )
+    ]

src/pretix/base/models/__init__.py

@@ -24,9 +24,10 @@
     cachedticket_name, generate_secret,
 )
 from .organizer import (
-    Organizer, Organizer_SettingsStore, Team, TeamAPIToken, TeamInvite,
+    Organizer, Organizer_SettingsStore, OrganizerBillingModel, Team,
+    TeamAPIToken, TeamInvite,
 )
 from .seating import Seat, SeatCategoryMapping, SeatingPlan
 from .tax import TaxRule
-from .vouchers import Voucher
+from .vouchers import InvoiceVoucher, Voucher
 from .waitinglist import WaitingListEntry

src/pretix/base/models/billing.py

@@ -7,6 +7,8 @@
 
 from pretix.base.models import LoggedModel
 
+from .choices import PriceModeChoices
+
 
 class BillingInvoice(LoggedModel):
     STATUS_PENDING = "n"
@@ -30,6 +32,10 @@ class BillingInvoice(LoggedModel):
     currency = models.CharField(max_length=3)
 
     ticket_fee = models.DecimalField(max_digits=10, decimal_places=2)
+    final_ticket_fee = models.DecimalField(max_digits=10, decimal_places=2, default=0)
+    voucher_discount = models.DecimalField(max_digits=10, decimal_places=2, default=0)
+    voucher_price_mode = models.CharField(max_length=20, null=True, blank=True, choices=PriceModeChoices.choices)
+    voucher_value = models.DecimalField(max_digits=10, decimal_places=2, default=0)
     payment_method = models.CharField(max_length=20, null=True, blank=True)
     paid_datetime = models.DateTimeField(null=True, blank=True)
     note = models.TextField(null=True, blank=True)

src/pretix/base/models/choices.py

@@ -0,0 +1,9 @@
+from django.db import models
+from django.utils.translation import gettext_lazy as _
+
+
+class PriceModeChoices(models.TextChoices):
+    NONE = 'none', _('No effect')
+    SET = 'set', _('Set product price to')
+    SUBTRACT = 'subtract', _('Subtract from product price')
+    PERCENT = 'percent', _('Reduce product price by (%)')

src/pretix/base/models/organizer.py

@@ -464,6 +464,13 @@ class OrganizerBillingModel(models.Model):
         verbose_name=_("Tax ID"),
     )
 
+    invoice_voucher = models.ForeignKey(
+        "pretixbase.InvoiceVoucher",
+        on_delete=models.CASCADE,
+        related_name="billing",
+        null=True
+    )
+
     stripe_customer_id = models.CharField(
         max_length=255,
         verbose_name=_("Stripe Customer ID"),

src/pretix/base/models/vouchers.py

@@ -16,6 +16,7 @@
 
 from ..decimal import round_decimal
 from .base import LoggedModel
+from .choices import PriceModeChoices
 from .event import Event, SubEvent
 from .items import Item, ItemVariation, Quota
 from .orders import Order, OrderPosition
@@ -81,12 +82,6 @@ class Voucher(LoggedModel):
     * You need to either select a quota or an item
     * If you select an item that has variations but do not select a variation, you cannot set block_quota
     """
-    PRICE_MODES = (
-        ('none', _('No effect')),
-        ('set', _('Set product price to')),
-        ('subtract', _('Subtract from product price')),
-        ('percent', _('Reduce product price by (%)')),
-    )
 
     event = models.ForeignKey(
         Event,
@@ -144,8 +139,8 @@ class Voucher(LoggedModel):
     price_mode = models.CharField(
         verbose_name=_("Price mode"),
         max_length=100,
-        choices=PRICE_MODES,
-        default='none'
+        choices=PriceModeChoices.choices,
+        default=PriceModeChoices.NONE
     )
     value = models.DecimalField(
         verbose_name=_("Voucher value"),
@@ -506,12 +501,6 @@ def budget_used(self):
 
 
 class InvoiceVoucher(LoggedModel):
-    PRICE_MODES = (
-        ('none', _('No effect')),
-        ('set', _('Set product price to')),
-        ('subtract', _('Subtract from product price')),
-        ('percent', _('Reduce product price by (%)')),
-    )
     code = models.CharField(
         verbose_name=_("Voucher code"),
         max_length=255, default=generate_code,
@@ -542,8 +531,8 @@ class InvoiceVoucher(LoggedModel):
     price_mode = models.CharField(
         verbose_name=_("Price mode"),
         max_length=100,
-        choices=PRICE_MODES,
-        default='none'
+        choices=PriceModeChoices.choices,
+        default=PriceModeChoices.NONE
     )
     value = models.DecimalField(
         verbose_name=_("Voucher value"),
@@ -583,3 +572,27 @@ def is_active(self):
         if self.valid_until and self.valid_until < now():
             return False
         return True
+
+    def calculate_price(self, original_price: Decimal, max_discount: Decimal=None, event: Event=None) -> Decimal:
+        """
+        Returns how the price given in original_price would be modified if this
+        voucher is applied, i.e. replaced by a different price or reduced by a
+        certain percentage. If the voucher does not modify the price, the
+        original price will be returned.
+        """
+        if self.value is not None:
+            if self.price_mode == 'set':
+                p = self.value
+            elif self.price_mode == 'subtract':
+                p = max(original_price - self.value, Decimal('0.00'))
+            elif self.price_mode == 'percent':
+                p = round_decimal(original_price * (Decimal('100.00') - self.value) / Decimal('100.00'))
+            else:
+                p = original_price
+            places = settings.CURRENCY_PLACES.get(event.currency, 2)
+            if places < 2:
+                p = p.quantize(Decimal('1') / 10 ** places, ROUND_HALF_UP)
+            if max_discount is not None:
+                p = max(p, original_price - max_discount)
+            return p
+        return original_price

src/pretix/control/forms/organizer_forms/organizer_form.py

@@ -5,6 +5,7 @@
 
 from pretix.base.forms import I18nModelForm
 from pretix.base.models.organizer import Organizer, OrganizerBillingModel
+from pretix.base.models.vouchers import InvoiceVoucher
 from pretix.helpers.countries import CachedCountries, get_country_name
 from pretix.helpers.stripe_utils import (
     create_stripe_customer, update_customer_info,
@@ -44,6 +45,7 @@ class Meta:
             "country",
             "preferred_language",
             "tax_id",
+            "invoice_voucher"
         ]
 
     primary_contact_name = forms.CharField(
@@ -132,6 +134,14 @@ class Meta:
         required=False,
     )
 
+    invoice_voucher = forms.CharField(
+        label=_("Invoice Voucher"),
+        help_text=_("If you have a voucher code, enter it here."),
+        max_length=255,
+        widget=forms.TextInput(attrs={"placeholder": ""}),
+        required=False,
+    )
+
     def __init__(self, *args, **kwargs):
         self.organizer = kwargs.pop("organizer", None)
         self.warning_message = None
@@ -162,6 +172,25 @@ def validate_vat_number(self, country_code, vat_number):
         result = pyvat.is_vat_number_format_valid(vat_number, country_code)
         return result
 
+    def clean_invoice_voucher(self):
+        voucher_code = self.cleaned_data['invoice_voucher']
+        if not voucher_code:
+            return None
+
+        voucher_instance = InvoiceVoucher.objects.filter(code=voucher_code).first()
+        if not voucher_instance:
+            raise forms.ValidationError("Voucher code not found!")
+
+        if not voucher_instance.is_active():
+            raise forms.ValidationError("The voucher code has either expired or reached its usage limit.")
+
+        if voucher_instance.limit_organizer.exists():
+            limit_organizer = voucher_instance.limit_organizer.values_list("id", flat=True)
+            if self.organizer.id not in limit_organizer:
+                raise forms.ValidationError("Voucher code is not valid for this organizer!")
+
+        return voucher_instance
+
     def clean(self):
         cleaned_data = super().clean()
         country_code = cleaned_data.get("country")
@@ -174,14 +203,16 @@ def clean(self):
                 self.add_error("tax_id", _("Invalid VAT number for {}".format(country_name)))
 
     def save(self, commit=True):
+        def set_attribute(instance):
+            for field in self.Meta.fields:
+                setattr(instance, field, self.cleaned_data[field])
+
         instance = OrganizerBillingModel.objects.filter(
             organizer_id=self.organizer.id
         ).first()
 
         if instance:
-            for field in self.Meta.fields:
-                setattr(instance, field, self.cleaned_data[field])
-
+            set_attribute(instance)
             if commit:
                 update_customer_info(
                     instance.stripe_customer_id,
@@ -191,9 +222,7 @@ def save(self, commit=True):
                 instance.save()
         else:
             instance = OrganizerBillingModel(organizer_id=self.organizer.id)
-            for field in self.Meta.fields:
-                setattr(instance, field, self.cleaned_data[field])
-
+            set_attribute(instance)
             if commit:
                 stripe_customer = create_stripe_customer(
                     email=self.cleaned_data.get("primary_contact_email"),

src/pretix/control/templates/pretixcontrol/organizers/billing.html

@@ -28,6 +28,7 @@ <h1>{% trans "Billing settings" %}</h1>
                 {% bootstrap_field form.city layout="control" %}
                 {% bootstrap_field form.country layout="control" %}
                 {% bootstrap_field form.tax_id layout="control" %}
+                {% bootstrap_field form.invoice_voucher layout="control" %}
                 {% bootstrap_field form.preferred_language layout="control" %}
                 <div class="form-group submit-group">
                     <button type="submit" class="btn btn-primary btn-save">