Restructure solution layout by module

src/Policy/__Libraries/StellaOps.Policy/Audit/IPolicyAuditRepository.cs

@@ -0,0 +1,12 @@
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace StellaOps.Policy;
+
+public interface IPolicyAuditRepository
+{
+    Task AddAsync(PolicyAuditEntry entry, CancellationToken cancellationToken = default);
+
+    Task<IReadOnlyList<PolicyAuditEntry>> ListAsync(int limit, CancellationToken cancellationToken = default);
+}

src/Policy/__Libraries/StellaOps.Policy/Audit/InMemoryPolicyAuditRepository.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace StellaOps.Policy;
+
+public sealed class InMemoryPolicyAuditRepository : IPolicyAuditRepository
+{
+    private readonly List<PolicyAuditEntry> _entries = new();
+    private readonly SemaphoreSlim _mutex = new(1, 1);
+
+    public async Task AddAsync(PolicyAuditEntry entry, CancellationToken cancellationToken = default)
+    {
+        if (entry is null)
+        {
+            throw new ArgumentNullException(nameof(entry));
+        }
+
+        await _mutex.WaitAsync(cancellationToken).ConfigureAwait(false);
+        try
+        {
+            _entries.Add(entry);
+            _entries.Sort(static (left, right) => left.CreatedAt.CompareTo(right.CreatedAt));
+        }
+        finally
+        {
+            _mutex.Release();
+        }
+    }
+
+    public async Task<IReadOnlyList<PolicyAuditEntry>> ListAsync(int limit, CancellationToken cancellationToken = default)
+    {
+        await _mutex.WaitAsync(cancellationToken).ConfigureAwait(false);
+        try
+        {
+            IEnumerable<PolicyAuditEntry> query = _entries;
+            if (limit > 0)
+            {
+                query = query.TakeLast(limit);
+            }
+
+            return query.ToImmutableArray();
+        }
+        finally
+        {
+            _mutex.Release();
+        }
+    }
+}