feature: Observation Ingest, Synchronous Alert Detection, and Alert Lifecycle

2026-06-16 21:05:06 +08:00
parent 882d4af3e6
commit de603df151
26 changed files with 1471 additions and 5 deletions
@@ -0,0 +1,59 @@
+using Microsoft.EntityFrameworkCore;
+
+public class ObservationQueryService : IObservationQueryService
+{
+    private readonly AppDbContext _db;
+
+    public ObservationQueryService(AppDbContext db) => _db = db;
+
+    public async Task<CursorPage<Observation>> GetHistoryAsync(
+        Guid encounterId,
+        string? code,
+        DateTimeOffset? from,
+        DateTimeOffset? to,
+        int limit,
+        string? cursorToken)
+    {
+        limit = Math.Clamp(limit, 1, 100);
+        var cursor = ObservationCursor.Decode(cursorToken);
+
+        var query = _db.Observations
+            .AsNoTracking()
+            .Where(o => o.EncounterId == encounterId);
+
+        if (!string.IsNullOrEmpty(code))
+            query = query.Where(o => o.ObservationCode == code);
+
+        if (from.HasValue)
+            query = query.Where(o => o.RecordedAt >= from.Value);
+
+        if (to.HasValue)
+            query = query.Where(o => o.RecordedAt <= to.Value);
+
+        if (cursor is not null)
+        {
+            // Keyset condition for ORDER BY recorded_at DESC, id DESC:
+            // next page starts just below the cursor position
+            var cursorTime = cursor.RecordedAt;
+            var cursorId = cursor.Id;
+            query = query.Where(o =>
+                o.RecordedAt < cursorTime ||
+                (o.RecordedAt == cursorTime && o.Id.CompareTo(cursorId) < 0));
+        }
+
+        var items = await query
+            .OrderByDescending(o => o.RecordedAt)
+            .ThenByDescending(o => o.Id)
+            .Take(limit + 1)   // fetch one extra to know if there is a next page
+            .ToListAsync();
+
+        var hasMore = items.Count > limit;
+        if (hasMore) items.RemoveAt(limit);
+
+        var nextCursor = hasMore
+            ? new ObservationCursor(items[^1].RecordedAt, items[^1].Id).Encode()
+            : null;
+
+        return new CursorPage<Observation>(items, nextCursor, hasMore);
+    }
+}