feat: implement real-time SSE event architecture with Redis stream integration and add associated validation tests

web/realtime_event_store_factory.py

@@ -0,0 +1,45 @@
+"""Factory for selecting the realtime observation event store."""
+
+from __future__ import annotations
+
+import os
+from typing import Any, Callable, Optional
+
+from loguru import logger
+
+from web.realtime_event_store import RealtimeEventStore
+from web.redis_realtime_event_store import RedisRealtimeEventStore
+
+
+def _truthy(value: Optional[str], *, default: bool = False) -> bool:
+    raw = str(value or "").strip().lower()
+    if not raw:
+        return default
+    return raw in {"1", "true", "yes", "on"}
+
+
+def create_realtime_event_store(
+    *,
+    db_path: Optional[str] = None,
+    redis_client: Any = None,
+    redis_store_builder: Optional[Callable[..., Any]] = None,
+) -> Any:
+    mode = str(os.getenv("POLYWEATHER_EVENT_STORE") or "sqlite").strip().lower()
+    if mode in {"", "sqlite"}:
+        return RealtimeEventStore(db_path=db_path)
+
+    if mode != "redis":
+        logger.warning(f"Unknown POLYWEATHER_EVENT_STORE={mode!r}; using sqlite event store")
+        return RealtimeEventStore(db_path=db_path)
+
+    builder = redis_store_builder or RedisRealtimeEventStore
+    try:
+        kwargs = {"redis_client": redis_client} if redis_client is not None else {}
+        return builder(**kwargs)
+    except Exception:
+        if _truthy(os.getenv("POLYWEATHER_REDIS_REQUIRED"), default=True):
+            raise
+        logger.exception("Redis realtime event store unavailable; falling back to sqlite")
+        fallback = RealtimeEventStore(db_path=db_path)
+        setattr(fallback, "degraded_from", "redis")
+        return fallback