Squashed 'common/' content from commit 28b2939

git-subtree-dir: common
git-subtree-split: 28b2939037b5932ca5d5a6c734b292c012ac675f

src/cartsnitch_common/events.py

@@ -0,0 +1,28 @@
+"""Event bus helpers for Redis pub/sub."""
+
+from datetime import UTC, datetime
+from typing import Any, cast
+
+from redis import Redis
+
+from cartsnitch_common.constants import EventType
+from cartsnitch_common.schemas.events import EventEnvelope
+
+
+def publish_event(
+    redis_client: Redis,
+    event_type: EventType,
+    service: str,
+    payload: dict[str, Any],
+) -> int:
+    """Publish an event to the Redis pub/sub channel.
+
+    Returns the number of subscribers that received the message.
+    """
+    envelope = EventEnvelope(
+        event_type=event_type,
+        timestamp=datetime.now(UTC),
+        service=service,
+        payload=payload,
+    )
+    return cast(int, redis_client.publish(event_type.value, envelope.model_dump_json()))