update

http-api/app/rules/enrollment.py

@@ -5,8 +5,9 @@ from uuid import uuid4
 
 from layercake.dateutils import now, ttl
 from layercake.dynamodb import DynamoDBPersistenceLayer, KeyPair, TransactItems
+from layercake.strutils import md5_hash
 
-from conf import ORDER_TABLE
+from config import ORDER_TABLE
 from models import Course, Enrollment
 
 
@@ -23,6 +24,10 @@ class Author(TypedDict):
 class Vacancy(TypedDict): ...
 
 
+class DeduplicationWindow(TypedDict):
+    offset_days: int
+
+
 class LifecycleEvents(str, Enum):
     """Lifecycle events related to scheduling actions."""
 
@@ -49,20 +54,23 @@ def enroll(
     enrollment: Enrollment,
     *,
     tenant: Tenant,
+    vacancy: Vacancy | None = None,
+    deduplication_window: DeduplicationWindow | None = None,
     persistence_layer: DynamoDBPersistenceLayer,
 ) -> bool:
     """Enrolls a user into a course and schedules lifecycle events."""
     now_ = now()
     user = enrollment.user
     course = enrollment.course
+    tenant_id = tenant['id']
 
     transact = TransactItems(persistence_layer.table_name)
     transact.put(
         item={
             'sk': '0',
             'create_date': now_,
-            'metadata__tenant_id': tenant['id'],
-            'metadata__related_ids': {tenant['id'], user.id},
+            'metadata__tenant_id': tenant_id,
+            'metadata__related_ids': {tenant_id, user.id},
             **enrollment.model_dump(),
         },
     )
@@ -70,7 +78,7 @@ def enroll(
         item={
             'id': enrollment.id,
             'sk': 'metadata#tenant',
-            'tenant_id': f'ORG#{tenant["id"]}',
+            'tenant_id': f'ORG#{tenant_id}',
             'name': tenant['name'],
             'create_date': now_,
         },
@@ -97,7 +105,6 @@ def enroll(
             'ttl': ttl(start_dt=now_ + timedelta(days=course.access_period - 30)),
         },
     )
-
     transact.put(
         item={
             'id': enrollment.id,
@@ -110,6 +117,43 @@ def enroll(
         },
     )
 
+    # Prevents the user from enrolling in the same course again until
+    # the deduplication window expires or is removed
+    if deduplication_window:
+        lock_hash = md5_hash('%s%s' % (user.id, course.id))
+        offset_days = deduplication_window['offset_days']
+        ttl_expiration = ttl(
+            start_dt=now_ + timedelta(days=course.access_period - offset_days)
+        )
+        transact.put(
+            item={
+                'id': 'lock',
+                'sk': lock_hash,
+                'enrollment_id': enrollment.id,
+                'create_date': now_,
+                'ttl': ttl_expiration,
+            },
+            cond_expr='attribute_not_exists(sk)',
+        )
+        transact.put(
+            item={
+                'id': enrollment.id,
+                'sk': 'metadata#lock',
+                'hash': lock_hash,
+                'create_date': now_,
+                'ttl': ttl_expiration,
+            },
+        )
+        # Deduplication window can be recalculated if needed
+        transact.put(
+            item={
+                'id': enrollment.id,
+                'sk': 'metadata#deduplication_window',
+                'offset_days': offset_days,
+                'create_date': now_,
+            },
+        )
+
     return persistence_layer.transact_write_items(transact)