feat: send subscription renewal notification emails

billing/management/commands/generate_invoice.py

@@ -15,6 +15,8 @@
 from django.core.management.base import BaseCommand
 from django.core.exceptions import ValidationError
 from django.conf import settings
+from django.core.mail import send_mail
+from django.template.loader import render_to_string
 from django.contrib.auth import get_user_model
 
 from oauth2_provider.models import get_application_model
@@ -23,7 +25,7 @@ from oauth2_provider.generators import generate_client_id, generate_client_secre
 from accounts.utils import gen_secret
 from dash.models import Instance
 from infrastructure.models import InstanceCreated
-from billing.utils import generate_invoice, payment_fullfilled
+from billing.utils import generate_invoice, payment_fullfilled, get_invoice_link
 
 Application = get_application_model()
 
@@ -41,5 +43,27 @@ class Command(BaseCommand):
                         f"Payment not fulfilled for instance: {paid_instance.instance}"
                     )
                     payment = generate_invoice(instance=paid_instance.instance)
+                    owner = paid_instance.instance.owned_by
+                    ctx = {
+                        "username": owner.username,
+                        "payment": payment,
+                        "link": get_invoice_link(payment=payment),
+                    }
+
+                    body = render_to_string(
+                        "billing/emails/renew-subscription.txt",
+                        context=ctx,
+                    )
+
+                    email = owner.email
+                    sender = settings.DEFAULT_FROM_EMAIL
+
+                    send_mail(
+                        subject="[Gna!] Payment receipt your Hostea VM",
+                        message=body,
+                        from_email=f"No reply Gna!<{sender}>",  # TODO read from settings.py
+                        recipient_list=[email],
+                    )
+
         else:
             self.stdout.write("No instances available")

billing/templates/billing/emails/renew-subscription.txt

@@ -0,0 +1,17 @@
+Hello {{ username }}!
+
+Your Gna! VM subscription is due for renewal. Please click the link
+below to renew your subscription:
+
+{{link}}
+
+-----------------------------------------------------
+
+- Instance Name: {{ payment.instance_name }}
+- Configuration: {{payment.instance_configuration_id.name}}
+- Total Amount: {{payment.total}} {{payment.currency|upper}}
+
+We appreciate your business!
+
+Cheers,
+Gna! team