first claude draft

shared/events/factory.py

@@ -0,0 +1,101 @@
+"""Factory functions for creating event publishers and subscribers."""
+
+import os
+from enum import Enum
+
+from .base import EventPublisher, EventSubscriber
+from .redis_pubsub import RedisPubSubPublisher, RedisPubSubSubscriber
+
+
+class EventBackend(str, Enum):
+    """Supported event backends."""
+
+    REDIS_PUBSUB = "redis_pubsub"
+    REDIS_STREAMS = "redis_streams"  # Future
+    KAFKA = "kafka"  # Future
+
+
+def get_publisher(
+    backend: EventBackend | str | None = None,
+    source: str = "",
+    **kwargs,
+) -> EventPublisher:
+    """
+    Factory function to get an event publisher.
+
+    Args:
+        backend: The event backend to use (default: from EVENTS_BACKEND env var or redis_pubsub)
+        source: Identifier for the source service
+        **kwargs: Backend-specific options
+
+    Returns:
+        An EventPublisher instance
+
+    Environment variables:
+        EVENTS_BACKEND: Default backend (redis_pubsub, redis_streams, kafka)
+        REDIS_URL: Redis connection URL
+        KAFKA_BOOTSTRAP_SERVERS: Kafka bootstrap servers (future)
+    """
+    if backend is None:
+        backend = os.getenv("EVENTS_BACKEND", EventBackend.REDIS_PUBSUB)
+
+    if isinstance(backend, str):
+        backend = EventBackend(backend)
+
+    if backend == EventBackend.REDIS_PUBSUB:
+        redis_url = kwargs.get("redis_url") or os.getenv(
+            "REDIS_URL", "redis://localhost:6379"
+        )
+        return RedisPubSubPublisher(redis_url=redis_url, source=source)
+
+    elif backend == EventBackend.REDIS_STREAMS:
+        raise NotImplementedError("Redis Streams backend not yet implemented")
+
+    elif backend == EventBackend.KAFKA:
+        raise NotImplementedError("Kafka backend not yet implemented")
+
+    else:
+        raise ValueError(f"Unknown event backend: {backend}")
+
+
+def get_subscriber(
+    topics: list[str] | None = None,
+    backend: EventBackend | str | None = None,
+    **kwargs,
+) -> EventSubscriber:
+    """
+    Factory function to get an event subscriber.
+
+    Args:
+        topics: Topics to subscribe to
+        backend: The event backend to use (default: from EVENTS_BACKEND env var or redis_pubsub)
+        **kwargs: Backend-specific options
+
+    Returns:
+        An EventSubscriber instance
+
+    Environment variables:
+        EVENTS_BACKEND: Default backend (redis_pubsub, redis_streams, kafka)
+        REDIS_URL: Redis connection URL
+        KAFKA_BOOTSTRAP_SERVERS: Kafka bootstrap servers (future)
+    """
+    if backend is None:
+        backend = os.getenv("EVENTS_BACKEND", EventBackend.REDIS_PUBSUB)
+
+    if isinstance(backend, str):
+        backend = EventBackend(backend)
+
+    if backend == EventBackend.REDIS_PUBSUB:
+        redis_url = kwargs.get("redis_url") or os.getenv(
+            "REDIS_URL", "redis://localhost:6379"
+        )
+        return RedisPubSubSubscriber(redis_url=redis_url, topics=topics)
+
+    elif backend == EventBackend.REDIS_STREAMS:
+        raise NotImplementedError("Redis Streams backend not yet implemented")
+
+    elif backend == EventBackend.KAFKA:
+        raise NotImplementedError("Kafka backend not yet implemented")
+
+    else:
+        raise ValueError(f"Unknown event backend: {backend}")