From 68a187220cbb72208dcf38ec1b83989b06d8ac24 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9rgio=20Rafael=20Siqueira?=
 <osergiosiqueira@gmail.com>
Date: Fri, 25 Jul 2025 12:46:17 -0300
Subject: [PATCH] add billing

---
 order-events/app/events/billing/__init__.py   |   0
 .../app/events/billing/append_enrollment.py   | 125 ++++++++++++++++++
 2 files changed, 125 insertions(+)
 create mode 100644 order-events/app/events/billing/__init__.py
 create mode 100644 order-events/app/events/billing/append_enrollment.py

diff --git a/order-events/app/events/billing/__init__.py b/order-events/app/events/billing/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/order-events/app/events/billing/append_enrollment.py b/order-events/app/events/billing/append_enrollment.py
new file mode 100644
index 0000000..bfd3d23
--- /dev/null
+++ b/order-events/app/events/billing/append_enrollment.py
@@ -0,0 +1,125 @@
+from datetime import datetime, time, timedelta
+
+from aws_lambda_powertools import Logger
+from aws_lambda_powertools.utilities.data_classes import (
+    EventBridgeEvent,
+    event_source,
+)
+from aws_lambda_powertools.utilities.typing import LambdaContext
+from layercake.dateutils import now, ttl
+from layercake.dynamodb import (
+    DynamoDBPersistenceLayer,
+    KeyPair,
+    SortKey,
+    TransactKey,
+)
+from layercake.funcs import pick
+
+from boto3clients import dynamodb_client
+from config import COURSE_TABLE, ENROLLMENT_TABLE, ORDER_TABLE
+from utils import get_billing_period
+
+logger = Logger(__name__)
+order_layer = DynamoDBPersistenceLayer(ORDER_TABLE, dynamodb_client)
+enrollment_layer = DynamoDBPersistenceLayer(ENROLLMENT_TABLE, dynamodb_client)
+course_layer = DynamoDBPersistenceLayer(COURSE_TABLE, dynamodb_client)
+
+
+@event_source(data_class=EventBridgeEvent)
+@logger.inject_lambda_context
+def lambda_handler(event: EventBridgeEvent, context: LambdaContext) -> bool:
+    new_image = event.detail['new_image']
+    now_ = now()
+    enrollment_id = new_image['id']
+    org_id = new_image['org_id']
+    data = enrollment_layer.collection.get_items(
+        TransactKey(enrollment_id) + SortKey('0') + SortKey('author')
+    )
+
+    if not data:
+        logger.debug('Enrollment not found')
+        return False
+
+    start_date, end_date = get_billing_period(new_image['billing_day'])
+    pk = 'BILLING#ORG#{org_id}'.format(org_id=org_id)
+    sk = 'START#{start}#END#{end}'.format(
+        start=start_date.isoformat(),
+        end=end_date.isoformat(),
+    )
+
+    try:
+        with order_layer.transact_writer() as transact:
+            transact.put(
+                item={
+                    'id': pk,
+                    'sk': sk,
+                    'status': 'PENDING',
+                    'created_at': now_,
+                },
+                cond_expr='attribute_not_exists(sk)',
+                exc_cls=ExistingBillingConflictError,
+            )
+            transact.put(
+                item={
+                    'id': pk,
+                    'sk': f'{sk}#SCHEDULE#AUTO_CLOSE',
+                    'ttl': ttl(
+                        start_dt=datetime.combine(end_date, time()) + timedelta(days=1)
+                    ),
+                    'created_at': now_,
+                }
+            )
+    except ExistingBillingConflictError:
+        pass
+
+    try:
+        with order_layer.transact_writer() as transact:
+            author = data['author']
+            course_id = data['course']['id']
+            course = course_layer.collection.get_items(
+                KeyPair(
+                    pk=course_id,
+                    sk=SortKey('0', path_spec='metadata__unit_price'),
+                    rename_key='unit_price',
+                )
+                + KeyPair(
+                    pk=f'CUSTOM_PRICING#ORG#{org_id}',
+                    sk=SortKey(f'COURSE#{course_id}', path_spec='unit_price'),
+                    rename_key='unit_price',
+                ),
+                flatten_top=False,
+            )
+
+            transact.condition(
+                key=KeyPair(pk, sk),
+                cond_expr='attribute_exists(sk)',
+                exc_cls=BillingNotFoundError,
+            )
+            transact.put(
+                item={
+                    'id': pk,
+                    'sk': f'{sk}#ENROLLMENT#{enrollment_id}',
+                    'user': pick(('id', 'name'), data['user']),
+                    'course': pick(('id', 'name'), data['course']),
+                    'unit_price': course['unit_price'],
+                    'author': {
+                        'id': author['user_id'],
+                        'name': author['name'],
+                    },
+                    # Post-migration: uncomment the following line
+                    # 'enrolled_at': data['created_at'],
+                    'enrolled_at': data['create_date'],
+                    'created_at': now_,
+                },
+                cond_expr='attribute_not_exists(sk)',
+            )
+    except Exception:
+        return False
+    else:
+        return True
+
+
+class ExistingBillingConflictError(Exception): ...
+
+
+class BillingNotFoundError(Exception): ...