feat(backend): capture status and the stretches the archive was not recording

backend/src/utils/read/capture.py

@@ -0,0 +1,44 @@
+from datetime import datetime
+
+import asyncpg
+
+from utils.read.models import CaptureGap, CaptureStatus
+
+_STATUS = """
+SELECT started_at, seen_at, seen_at >= now() - interval '150 seconds' AS live
+FROM capture_uptime WHERE account_id = $1
+ORDER BY started_at DESC LIMIT 1
+"""
+
+_GAPS = """
+SELECT seen_at AS start, next_start AS "end"
+FROM (
+    SELECT seen_at,
+           lead(started_at) OVER (ORDER BY started_at) AS next_start
+    FROM capture_uptime WHERE account_id = $1
+) stretches
+WHERE next_start - seen_at > interval '30 minutes'
+  AND ($2::timestamptz IS NULL OR next_start >= $2)
+  AND ($3::timestamptz IS NULL OR seen_at <= $3)
+ORDER BY seen_at
+"""
+
+
+async def capture_status(pool: asyncpg.Pool, account_id: int) -> CaptureStatus:
+    row = await pool.fetchrow(_STATUS, account_id)
+    if row is None:
+        return CaptureStatus(live=False, since=None, last_seen=None)
+    return CaptureStatus(
+        live=row["live"], since=row["started_at"], last_seen=row["seen_at"]
+    )
+
+
+async def capture_gaps(
+    pool: asyncpg.Pool,
+    account_id: int,
+    *,
+    date_from: datetime | None = None,
+    date_to: datetime | None = None,
+) -> list[CaptureGap]:
+    rows = await pool.fetch(_GAPS, account_id, date_from, date_to)
+    return [CaptureGap(**dict(row)) for row in rows]