163 lines
5.2 KiB
Python
163 lines
5.2 KiB
Python
from datetime import timedelta
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from typing import NotRequired, Self, TypedDict
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from layercake.dateutils import now, ttl
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from layercake.dynamodb import DynamoDBPersistenceLayer, KeyPair
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from layercake.strutils import md5_hash
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from schemas import Enrollment
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Org = TypedDict('Org', {'org_id': str, 'name': str})
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DeduplicationWindow = TypedDict('DeduplicationWindow', {'offset_days': int})
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Subscription = TypedDict(
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'Subscription',
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{
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'org_id': str,
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'billing_day': int,
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'billing_period': NotRequired[str],
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},
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)
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class LinkedEntity(str):
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def __new__(cls, id: str, type: str) -> Self:
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return super().__new__(cls, '#'.join([type.lower(), id]))
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def __init__(self, id: str, type: str) -> None:
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# __init__ is used to store the parameters for later reference.
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# For immutable types like str, __init__ cannot change the instance's value.
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self.id = id
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self.type = type
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class DeduplicationConflictError(Exception):
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def __init__(self, *args):
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super().__init__('Enrollment already exists')
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def enroll(
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enrollment: Enrollment,
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*,
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org: Org | None = None,
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subscription: Subscription | None = None,
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linked_entities: frozenset[LinkedEntity] = frozenset(),
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deduplication_window: DeduplicationWindow | None = None,
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persistence_layer: DynamoDBPersistenceLayer,
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) -> bool:
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"""Enrolls a user into a course and schedules lifecycle events."""
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now_ = now()
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user = enrollment.user
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course = enrollment.course
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lock_hash = md5_hash('%s%s' % (user.id, course.id))
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access_expires_at = now_ + timedelta(days=course.access_period)
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with persistence_layer.transact_writer() as transact:
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transact.put(
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item={
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'sk': '0',
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'created_at': now_,
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'access_expires_at': access_expires_at,
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**enrollment.model_dump(),
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}
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| ({'subscription_covered': True} if subscription else {})
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| ({'tenant_id': org['org_id']} if org else {}),
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# Post-migration: uncomment the following line
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# | ({'org_id': org['org_id']} if org else {}),
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)
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# Relationships between this enrollment and its related entities
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for parent_entity in linked_entities:
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perent_id = parent_entity.id
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entity_sk = f'LINKED_ENTITIES#{parent_entity.type}'
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keyprefix = parent_entity.type.lower()
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# Parent knows the child
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transact.put(
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item={
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'id': perent_id,
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'sk': f'{entity_sk}#CHILD',
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'created_at': now_,
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f'{keyprefix}_id': enrollment.id,
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},
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cond_expr='attribute_not_exists(sk)',
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)
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# Child knows the parent
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transact.put(
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item={
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'id': enrollment.id,
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'sk': f'{entity_sk}#PARENT',
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'created_at': now_,
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f'{keyprefix}_id': perent_id,
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},
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cond_expr='attribute_not_exists(sk)',
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)
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if org:
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transact.put(
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item={
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'id': enrollment.id,
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# Post-migration: uncomment the following line
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# 'sk': 'ORG',
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'sk': 'tenant',
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'created_at': now_,
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}
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| org
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)
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if subscription:
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transact.put(
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item={
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'id': enrollment.id,
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'sk': 'METADATA#SUBSCRIPTION_COVERED',
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'created_at': now_,
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}
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| subscription,
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)
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# Prevents the user from enrolling in the same course again until
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# the deduplication window expires or is removed.
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if deduplication_window:
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offset_days = int(deduplication_window['offset_days'])
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ttl_ = ttl(
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start_dt=now_,
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days=course.access_period - offset_days,
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)
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transact.put(
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item={
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'id': 'LOCK',
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'sk': lock_hash,
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'enrollment_id': enrollment.id,
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'created_at': now_,
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'ttl': ttl_,
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},
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cond_expr='attribute_not_exists(sk)',
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exc_cls=DeduplicationConflictError,
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)
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transact.put(
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item={
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'id': enrollment.id,
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'sk': 'LOCK',
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'hash': lock_hash,
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'created_at': now_,
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'ttl': ttl_,
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},
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)
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# Deduplication window can be recalculated if needed
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transact.put(
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item={
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'id': enrollment.id,
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'sk': 'METADATA#DEDUPLICATION_WINDOW',
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'offset_days': offset_days,
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'created_at': now_,
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},
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)
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else:
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transact.condition(
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key=KeyPair('LOCK', lock_hash),
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cond_expr='attribute_not_exists(sk)',
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exc_cls=DeduplicationConflictError,
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)
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return True
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