Add discounts to the dashboard

The discounts come in the form of Stripe coupons.
The description can be edited in Stripe.
Currently, we have just a 10% and 15% coupon
based on the total campaign size.

They appear in:

- The create/edit flight screens (for staff).
  The discounts are not automatically applied yet.
  When a flight is renewed, the discount is renewed by default.
- They appear in the memo section of invoices
- They are displayed in the flight metadata to advertisers

adserver/admin.py

@@ -630,7 +630,10 @@ def action_create_draft_invoice(self, request, queryset):
             )
             return
 
+        # Any flight with the discount will result in the discount being in the memo
+        invoice_discount = None
         total_cost = 0  # In US cents
+
         for flight in flights:
             message_components = ["Advertising", flight.name]
             unit_amount = 0
@@ -641,16 +644,13 @@ def action_create_draft_invoice(self, request, queryset):
                 unit_amount = flight.cpc * 100  # Convert to US cents
                 quantity = flight.sold_clicks
             elif flight.cpm:
-                priced_by_view = bool(flight.sold_impressions % 1000)
-                if priced_by_view:
-                    print(unit_amount, quantity)
-                    unit_amount = flight.cpm / 10  # Convert to US cents
-                    message_components.append("${:.2f} CPM".format(flight.cpm))
-                    quantity = flight.sold_impressions
-                else:
-                    unit_amount = flight.cpm * 100  # Convert to US cents
-                    message_components.append("per 1k impressions")
-                    quantity = flight.sold_impressions // 1000
+                # Convert CPM to US cents (eg. $4.25 CPM -> 0.425 cents)
+                unit_amount = flight.cpm / 10
+                message_components.append("${:.2f} CPM".format(flight.cpm))
+                quantity = flight.sold_impressions
+
+            if flight.discount:
+                invoice_discount = flight.discount
 
             total_cost += unit_amount * quantity
 
@@ -670,14 +670,14 @@ def action_create_draft_invoice(self, request, queryset):
             )
 
         # https://stripe.com/docs/api/invoices/create
+        description = "Thanks for your business!"
+        if invoice_discount:
+            description = f"Includes {invoice_discount} discount. " + description
         inv = stripe.Invoice.create(
             customer=advertiser.djstripe_customer.id,
             auto_advance=False,  # Draft invoice
             collection_method="send_invoice",
-            # Check just under 3k just in case there's a rounding issue
-            description="Includes 10% volume discount"
-            if total_cost >= 290_000
-            else "Thanks for your business!",
+            description=description,
             custom_fields=[
                 {"name": "Advertiser", "value": advertiser.slug[:30]},
                 {

adserver/forms.py

@@ -103,6 +103,7 @@ class Meta:
             "targeting_parameters",
             "traffic_fill",
             "traffic_cap",
+            "discount",
         )
 
 
@@ -238,7 +239,8 @@ def __init__(self, *args, **kwargs):
                 ),
                 css_class="my-3",
             ),
-            # NOTE: remove this when this form is made for non-staff users
+            # NOTE: remove these when this form is made for non-staff users
+            Field("discount"),
             Field("priority_multiplier"),
             Fieldset(
                 _("Flight targeting"),
@@ -345,6 +347,7 @@ class Meta:
             "sold_clicks",
             "cpm",
             "sold_impressions",
+            "discount",
             "priority_multiplier",
         )
         widgets = {
@@ -536,7 +539,12 @@ def save(self, commit=True):
         instance = super().save(commit)
 
         # Copy flight fields that aren't part of the form
-        for field in ("targeting_parameters", "priority_multiplier", "traffic_cap"):
+        for field in (
+            "targeting_parameters",
+            "priority_multiplier",
+            "traffic_cap",
+            "discount",
+        ):
             setattr(instance, field, getattr(self.old_flight, field))
         instance.save()
 

adserver/migrations/0088_linked_discounts.py

@@ -0,0 +1,39 @@
+# Generated by Django 4.2.4 on 2023-10-10 22:08
+import django.db.models.deletion
+from django.db import migrations
+from django.db import models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("djstripe", "0012_2_8"),
+        ("adserver", "0087_publisher_allow_multiple_placements"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="flight",
+            name="discount",
+            field=models.ForeignKey(
+                blank=True,
+                default=None,
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                to="djstripe.coupon",
+            ),
+        ),
+        migrations.AddField(
+            model_name="historicalflight",
+            name="discount",
+            field=models.ForeignKey(
+                blank=True,
+                db_constraint=False,
+                default=None,
+                null=True,
+                on_delete=django.db.models.deletion.DO_NOTHING,
+                related_name="+",
+                to="djstripe.coupon",
+            ),
+        ),
+    ]

adserver/models.py

@@ -859,6 +859,13 @@ class Flight(TimeStampedModel, IndestructibleModel):
         verbose_name=_("Stripe invoices"),
         blank=True,
     )
+    discount = models.ForeignKey(
+        djstripe_models.Coupon,
+        on_delete=models.SET_NULL,
+        blank=True,
+        null=True,
+        default=None,
+    )
 
     history = HistoricalRecords()
 

adserver/templates/adserver/includes/flight-metadata.html

@@ -38,6 +38,10 @@
     <dt>{% trans 'Cost per 1,000 impressions (CPM)' %}</dt>
     <dd>${{ flight.cpm|floatformat:2 }}</dd>
   {% endif %}
+  {% if flight.discount %}
+    <dt title="{% trans 'The price above includes this discount.' %}" data-toggle="tooltip" data-placement="left">{% trans 'Discount' %}</dt>
+    <dd>{{ flight.discount }}</dd>
+  {% endif %}
   {% if flight.start_date %}
     <dt>{% trans 'Estimated start date' %}</dt>
     <dd>{{ flight.start_date }}</dd>