feat: add snapshot status endpoint

src/StreetNameRegistry.Projector/Snapshots/SnapshotsController.cs

@@ -0,0 +1,53 @@
+namespace StreetNameRegistry.Projector.Snapshots
+{
+    using System.Threading;
+    using System.Threading.Tasks;
+    using Asp.Versioning;
+    using Be.Vlaanderen.Basisregisters.Api;
+    using Dapper;
+    using Microsoft.AspNetCore.Mvc;
+    using Microsoft.Data.SqlClient;
+    using Microsoft.Extensions.Configuration;
+
+    [ApiVersion("1.0")]
+    [ApiRoute("snapshots")]
+    public class SnapshotsController : ApiController
+    {
+        private const string SnapshotConnectionStringKey = "Events";
+        private const string SnapshotVerificationsTableName = "[StreetNameRegistry].[SnapshotVerificationStates]";
+        private const string SnaphotsTableName = "[StreetNameRegistry].[Snapshots]";
+
+        [HttpGet]
+        public async Task<IActionResult> Get(
+            [FromServices] IConfiguration configuration,
+            CancellationToken cancellationToken)
+        {
+            await using var sqlConnection = new SqlConnection(configuration.GetConnectionString(SnapshotConnectionStringKey));
+            var failedSnapshotCount =
+                await sqlConnection.QuerySingleAsync<int>(
+                    $"SELECT Count(*) FROM {SnapshotVerificationsTableName} WHERE Status = 'Failed'",
+                    cancellationToken);
+
+            var differenceInDaysOfLastVerification =
+                await sqlConnection.QuerySingleAsync<int>(
+                    $"SELECT DATEDIFF(DAY," +
+                        $"(SELECT Created FROM {SnaphotsTableName} WHERE Id = (SELECT MAX(SnapshotId) FROM {SnapshotVerificationsTableName}))," +
+                        $"(SELECT MAX(Created) FROM [StreetNameRegistry].[Snapshots])) As DaysDiff",
+                    cancellationToken);
+
+            return Ok(new SnapshotStatusResponse(failedSnapshotCount, differenceInDaysOfLastVerification));
+        }
+    }
+
+    public sealed class SnapshotStatusResponse
+    {
+        public int FailedSnapshotsCount { get; set; }
+        public int DifferenceInDaysOfLastVerification { get; set; }
+
+        public SnapshotStatusResponse(int failedSnapshotsCount, int differenceInDaysOfLastVerification)
+        {
+            FailedSnapshotsCount = failedSnapshotsCount;
+            DifferenceInDaysOfLastVerification = differenceInDaysOfLastVerification;
+        }
+    }
+}