feat: add event watcher

backend/src/utils/read/watches.py

@@ -6,6 +6,9 @@ import asyncpg
 
 from utils.read.models import AlertView, Page, WatchView
 
+WATCHES_CHANGED_CHANNEL = "watches_changed"
+ALERTS_CHANGED_CHANNEL = "alerts_changed"
+
 _WATCH_COLS = "id, account_id, kind, params, enabled, created_at, updated_at"
 _ALERT_COLS = "id, account_id, watch_id, ts, payload, seen, created_at"
 
@@ -55,6 +58,7 @@ async def create_watch(
         json.dumps(params),
         enabled,
     )
+    await pool.execute(f"NOTIFY {WATCHES_CHANGED_CHANNEL}")
     return _to_watch(row)
 
 
@@ -68,12 +72,18 @@ async def update_watch(
         json.dumps(params),
         enabled,
     )
-    return _to_watch(row) if row else None
+    if row is None:
+        return None
+    await pool.execute(f"NOTIFY {WATCHES_CHANGED_CHANNEL}")
+    return _to_watch(row)
 
 
 async def delete_watch(pool: asyncpg.Pool, watch_id: int) -> bool:
     result = await pool.execute("DELETE FROM watches WHERE id = $1", watch_id)
-    return result.endswith("1")
+    if not result.endswith("1"):
+        return False
+    await pool.execute(f"NOTIFY {WATCHES_CHANGED_CHANNEL}")
+    return True
 
 
 async def list_alerts(
@@ -95,16 +105,27 @@ async def list_alerts(
 
 
 async def insert_alert(
-    pool: asyncpg.Pool, account_id: int, watch_id: int, payload: dict[str, Any]
-) -> AlertView:
+    pool: asyncpg.Pool,
+    account_id: int,
+    watch_id: int,
+    payload: dict[str, Any],
+    *,
+    dedup_key: str | None = None,
+) -> AlertView | None:
     row = await pool.fetchrow(
-        "INSERT INTO alerts (account_id, watch_id, ts, payload) "  # noqa: S608
-        f"VALUES ($1, $2, $3, $4::jsonb) RETURNING {_ALERT_COLS}",
+        "INSERT INTO alerts (account_id, watch_id, ts, payload, seen, dedup_key) "  # noqa: S608
+        "VALUES ($1, $2, $3, $4::jsonb, false, $5) "
+        "ON CONFLICT (watch_id, dedup_key) WHERE dedup_key IS NOT NULL "
+        f"DO NOTHING RETURNING {_ALERT_COLS}",
         account_id,
         watch_id,
         datetime.now(UTC),
         json.dumps(payload),
+        dedup_key,
     )
+    if row is None:
+        return None
+    await pool.execute(f"NOTIFY {ALERTS_CHANGED_CHANNEL}")
     return _to_alert(row)