Add basic subscriptions and a partial implementation of the infra backing

src/services/subscription.py

@@ -0,0 +1,105 @@
+import abc
+from datetime import datetime
+from src.services.publications import (
+    OrderProfile as PublicationOrderProfile,
+    Sequence as PublicationSequence,
+    Publication,
+)
+from src.services.users.data import UserProfile
+from dataclasses import dataclass
+
+SubscriptionId = int
+
+
+@dataclass
+class SubscriptionCreateParams:
+    user_id: int
+    order_id: int
+
+
+@dataclass
+class Subscription:
+    id: SubscriptionId
+    user: UserProfile
+    publication_order: PublicationOrderProfile
+    sequence_seen: int
+    start: datetime
+
+
+@dataclass
+class UpdateSubscription:
+    id: int
+    user_id: int
+    publication_order_id: int | None = None
+    sequence_seen: int | None = None
+    start: datetime | None = None
+
+
+@dataclass
+class AvailableSubscriptionEntry:
+    publication: Publication
+    available_since: datetime
+    order: PublicationOrderProfile
+    sequence: PublicationSequence
+
+
+class SubscriptionRepo(abc.ABC):
+    @abc.abstractmethod
+    def get_subscriptions_for_user(self, user_id: int) -> list[Subscription]:
+        pass
+
+    @abc.abstractmethod
+    def get_subscription_by_id(self, sub_id: SubscriptionId) -> Subscription | None:
+        pass
+
+    @abc.abstractmethod
+    def create_subscription_for_user(self, user_id: int, order_id: int) -> Subscription:
+        pass
+
+    @abc.abstractmethod
+    def delete_subscription(self, subscription_id: SubscriptionId):
+        pass
+
+    @abc.abstractmethod
+    def update_subscription(self, subscription: UpdateSubscription) -> Subscription:
+        pass
+
+    @abc.abstractmethod
+    def get_available_entries(self, user_id: int) -> dict[SubscriptionId, list[AvailableSubscriptionEntry]]:
+        pass
+
+    @abc.abstractmethod
+    def get_unseen_available_subscription_entries(self, user_id: int) -> list[AvailableSubscriptionEntry]:
+        """
+        Get all publication entries that _should_ be available to the user given the timeline but are newer than the
+        `sequence_seen` value from the subscription
+        """
+        pass
+
+
+class SubscriptionService:
+    def __init__(self, repo: SubscriptionRepo):
+        self._repo = repo
+
+    def get_subscriptions(self, user_id: int) -> list[Subscription]:
+        return self._repo.get_subscriptions_for_user(user_id)
+
+    def get_updates(self, user_id: int) -> list[AvailableSubscriptionEntry]:
+        return self._repo.get_unseen_available_subscription_entries(user_id)
+
+    def get_all_available_entries(self, user_id: int) -> dict[SubscriptionId, list[AvailableSubscriptionEntry]]:
+        return self._repo.get_available_entries(user_id)
+
+    def create_suscription(self, params: SubscriptionCreateParams) -> Subscription:
+        return self._repo.create_subscription_for_user(params.user_id, params.order_id)
+
+    def delete_subcription(self, user_id: int, subscription_id: SubscriptionId):
+        subscription = self._repo.get_subscription_by_id(subscription_id)
+        if subscription is None:
+            # TODO Domain error types
+            raise RuntimeError('not found')
+        if subscription.user.id != user_id:
+            # TODO: Domain error types
+            raise RuntimeError('Cannot delete a subscription for another user')
+
+        self._repo.delete_subscription(subscription_id)