feature: Prometheus Metrics, Supervisor Dashboard, and Promotion Retry Job

2026-06-27 13:29:04 +08:00
parent e22d33b654
commit 04bdb7e85c
31 changed files with 4482 additions and 259 deletions
@@ -0,0 +1,78 @@
+using Microsoft.EntityFrameworkCore;
+
+/// <summary>
+/// Provides cursor-paginated access to the audit trail of digitization events
+/// for a given batch. Events are ordered by occurred_at ascending with id
+/// as a tie-breaker for events at the same timestamp.
+/// </summary>
+public class BatchEventService : IBatchEventService
+{
+    private readonly AppDbContext _db;
+    private const int MaxPageSize = 200;
+    private const int DefaultPageSize = 50;
+
+    public BatchEventService(AppDbContext db)
+    {
+        _db = db;
+    }
+
+    public async Task<CursorPagedResult<BatchEventResponse>> GetEventsAsync(
+        Guid batchId, DateTimeOffset? after, int pageSize)
+    {
+        // Validate batch exists
+        var batchExists = await _db.DigitizationBatches
+            .AnyAsync(b => b.Id == batchId);
+
+        if (!batchExists)
+            throw new NotFoundException("Batch not found.", "BATCH_NOT_FOUND");
+
+        // Clamp page size
+        pageSize = Math.Clamp(pageSize, 1, MaxPageSize);
+
+        // Build query
+        var query = _db.DigitizationEvents
+            .AsNoTracking()
+            .Include(e => e.Actor)
+            .Where(e => e.BatchId == batchId);
+
+        // Apply cursor filter — only events strictly after the cursor timestamp
+        if (after.HasValue)
+        {
+            query = query.Where(e => e.OccurredAt > after.Value);
+        }
+
+        // Fetch pageSize+1 rows to determine HasMore without a COUNT query
+        var events = await query
+            .OrderBy(e => e.OccurredAt)
+            .ThenBy(e => e.Id) // tie-breaker for events at the same timestamp
+            .Take(pageSize + 1)
+            .Select(e => new BatchEventResponse(
+                e.Id,
+                e.BatchId,
+                e.EventType.ToDbString(),
+                e.ActorUserId,
+                e.Actor.Username,
+                e.Actor.FullName,
+                e.OccurredAt,
+                e.MetadataJson))
+            .ToListAsync();
+
+        var hasMore = events.Count > pageSize;
+        var page = hasMore ? events.Take(pageSize).ToList() : events;
+
+        // Build next cursor from the last item's OccurredAt
+        string? nextCursor = null;
+        if (hasMore && page.Count > 0)
+        {
+            var lastEvent = page[^1];
+            // ISO-8601 round-trip format preserves full precision
+            nextCursor = lastEvent.OccurredAt.ToString("o");
+        }
+
+        return new CursorPagedResult<BatchEventResponse>(
+            Items: page,
+            PageSize: pageSize,
+            NextCursor: nextCursor,
+            HasMore: hasMore);
+    }
+}