release: bump version to 0.52.0

backend/app/services/vessel_ais_aggregation.py

@@ -6,6 +6,7 @@ import json
 from typing import Any, Iterable
 
 from sqlalchemy import select
+from sqlalchemy import Float
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.models.vessel import AISConflictRecord, AISRawObservation, AISSourceHealth
@@ -17,6 +18,10 @@ from app.services.vessel_types import normalize_vessel_type_name
 
 VESSEL_AIS_SCHEMA = "vessel_ais"
 DEFAULT_AGGREGATION_WINDOW_HOURS = 24
+DEFAULT_SNAPSHOT_WINDOW_MINUTES = 60
+MAX_SNAPSHOT_LIMIT = 5000
+MAX_SNAPSHOT_CANDIDATE_MULTIPLIER = 20
+MAX_SNAPSHOT_CANDIDATE_OBSERVATIONS = 100_000
 BARENTSWATCH_DELIVERY_MODE = "polling"
 BARENTSWATCH_TRANSPORT = "http"
 AISSTREAM_DELIVERY_MODE = "realtime_stream"
@@ -564,6 +569,46 @@ async def get_aggregated_vessels(
     return vessels
 
 
+async def get_aggregated_vessels_snapshot(
+    db: AsyncSession,
+    *,
+    bbox: tuple[float, float, float, float],
+    limit: int = 1000,
+    observed_since: datetime | None = None,
+) -> list[dict[str, Any]]:
+    """Return a bounded viewport snapshot without loading the global AIS window."""
+
+    observed_since = observed_since or (
+        datetime.now(UTC) - timedelta(minutes=DEFAULT_SNAPSHOT_WINDOW_MINUTES)
+    )
+    safe_limit = min(max(int(limit or 1000), 1), MAX_SNAPSHOT_LIMIT)
+    candidate_limit = min(
+        max(safe_limit * MAX_SNAPSHOT_CANDIDATE_MULTIPLIER, safe_limit),
+        MAX_SNAPSHOT_CANDIDATE_OBSERVATIONS,
+    )
+    lon_min, lat_min, lon_max, lat_max = bbox
+    payload_lon = AISRawObservation.normalized_payload["lon"].as_string().cast(Float)
+    payload_lat = AISRawObservation.normalized_payload["lat"].as_string().cast(Float)
+
+    stmt = (
+        select(AISRawObservation)
+        .where(AISRawObservation.target_schema == VESSEL_AIS_SCHEMA)
+        .where(AISRawObservation.observed_at >= observed_since)
+        .where(payload_lon >= lon_min)
+        .where(payload_lon <= lon_max)
+        .where(payload_lat >= lat_min)
+        .where(payload_lat <= lat_max)
+        .order_by(AISRawObservation.observed_at.desc(), AISRawObservation.id.desc())
+        .limit(candidate_limit)
+    )
+
+    result = await db.execute(stmt)
+    if not hasattr(result, "scalars"):
+        return []
+    vessels = await aggregate_vessel_observations(db, result.scalars().all())
+    return vessels[:safe_limit]
+
+
 async def get_aggregated_vessel(db: AsyncSession, mmsi: int) -> dict[str, Any] | None:
     observations = await get_vessel_raw_observations(db, mmsi, limit=1000)
     vessels = await aggregate_vessel_observations(db, observations)