feat: creatives and external channels

src/usecase/creative/get_creative.py

@@ -0,0 +1,28 @@
+import logging
+from typing import TYPE_CHECKING
+
+from src import domain, dto
+
+if TYPE_CHECKING:
+    from .. import Usecase
+
+log = logging.getLogger(__name__)
+
+
+async def get_creative(self: 'Usecase', input: dto.GetCreativeInput) -> dto.CreativeOutput:
+    async with self.database.transaction():
+        creative = await self.database.get_creative(input.user_id, input.creative_id)
+        if not creative:
+            log.warning('User %s attempted to access unavailable creative %s', input.user_id, input.creative_id)
+            raise domain.CreativeNotFound(input.creative_id)
+
+    return dto.CreativeOutput(
+        id=creative.id,
+        name=creative.name,
+        text=creative.text,
+        target_channel_id=creative.target_channel_id,
+        target_channel_title=creative.target_channel.title,
+        created_at=creative.created_at,
+        status=creative.status,
+        purchases_count=creative.purchases_count,
+    )