fix errors of Degraded Operations Visibility

VigilCareClinicalAPI/Services/OperationsService.cs

@@ -16,34 +16,39 @@ public class OperationsService : IOperationsService
     public async Task<IReadOnlyList<GatewayFleetItem>> GetGatewayFleetAsync(
         GatewayFleetFilter filter, CancellationToken ct)
     {
-        await using var conn = new NpgsqlConnection(_db.Database.GetConnectionString());
-        await conn.OpenAsync(ct);
+        var query = _db.WardGateways
+            .AsNoTracking()
+            .Include(g => g.Site)
+            .AsQueryable();
 
-        const string sql = """
-            SELECT
-              g.id,
-              g.gateway_code AS GatewayCode,
-              g.department AS Department,
-              s.site_code AS SiteCode,
-              s.name AS SiteName,
-              g.status AS Status,
-              g.reported_buffer_depth AS ReportedBufferDepth,
-              g.last_heartbeat_at AS LastHeartbeatAt,
-              g.last_sync_at AS LastSyncAt,
-              EXTRACT(EPOCH FROM (NOW() - g.last_heartbeat_at)) / 60 AS MinutesSinceHeartbeat
-            FROM ward_gateways g
-            JOIN clinical_sites s ON s.id = g.site_id
-            WHERE (@Status IS NULL OR g.status = @Status)
-              AND (@SiteId IS NULL OR g.site_id = @SiteId)
-            ORDER BY g.status DESC, MinutesSinceHeartbeat DESC NULLS LAST
-            """;
-
-        var rows = await conn.QueryAsync<GatewayFleetItem>(sql, new
+        if (!string.IsNullOrEmpty(filter.Status))
         {
-            Status = filter.Status,
-            SiteId = filter.SiteId
-        });
-        return rows.ToList();
+            var status = GatewayStatusExtensions.FromDbString(filter.Status);
+            query = query.Where(g => g.Status == status);
+        }
+
+        if (filter.SiteId is Guid siteId)
+            query = query.Where(g => g.SiteId == siteId);
+
+        var now = DateTimeOffset.UtcNow;
+        return await query
+            .OrderByDescending(g => g.Status)
+            .ThenByDescending(g => g.LastHeartbeatAt == null)
+            .ThenByDescending(g => g.LastHeartbeatAt)
+            .Select(g => new GatewayFleetItem(
+                g.Id,
+                g.GatewayCode,
+                g.Department,
+                g.Site.SiteCode,
+                g.Site.Name,
+                g.Status.ToDbString(),
+                g.ReportedBufferDepth,
+                g.LastHeartbeatAt,
+                g.LastSyncAt,
+                g.LastHeartbeatAt == null
+                    ? null
+                    : (double?)(now - g.LastHeartbeatAt.Value).TotalMinutes))
+            .ToListAsync(ct);
     }
 
     public async Task<GatewayDetailResponse> GetGatewayDetailAsync(Guid gatewayId, CancellationToken ct)