1 files changed, 55 insertions, 0 deletions
diff --git a/src/Agent.App/Logging/RollingFileLog.cs b/src/Agent.App/Logging/RollingFileLog.cs
new file mode 100644
index 0000000..801768d
--- /dev/null
+++ b/src/Agent.App/Logging/RollingFileLog.cs
@@ -0,0 +1,55 @@
+using System.Globalization;
+
+namespace Agent.App.Logging;
+
+public sealed class RollingFileLog : IDisposable
+{
+    private readonly object _sync = new();
+    private readonly string _path;
+    private readonly long _maxBytes;
+    private readonly int _retainedFiles;
+    private StreamWriter _writer;
+
+    public RollingFileLog(string directory, long maxBytes, int retainedFiles)
+    {
+        Directory.CreateDirectory(directory);
+        _path = Path.Combine(directory, "application.log");
+        _maxBytes = maxBytes;
+        _retainedFiles = retainedFiles;
+        _writer = Open();
+    }
+
+    public void Information(string message) => Write("INF", message);
+    public void Error(string message) => Write("ERR", message);
+
+    private void Write(string level, string message)
+    {
+        lock (_sync)
+        {
+            if (_writer.BaseStream.Length >= _maxBytes) Rotate();
+            string line = string.Create(CultureInfo.InvariantCulture, $"{DateTimeOffset.UtcNow:O} [{level}] {message}");
+            Console.Error.WriteLine(line);
+            _writer.WriteLine(line);
+            _writer.Flush();
+        }
+    }
+
+    private StreamWriter Open() => new(new FileStream(_path, FileMode.Append, FileAccess.Write, FileShare.Read), new System.Text.UTF8Encoding(false));
+
+    private void Rotate()
+    {
+        _writer.Dispose();
+        for (int index = _retainedFiles - 1; index >= 1; index--)
+        {
+            string source = $"{_path}.{index}";
+            if (File.Exists(source)) File.Move(source, $"{_path}.{index + 1}", true);
+        }
+        if (File.Exists(_path)) File.Move(_path, $"{_path}.1", true);
+        _writer = Open();
+    }
+
+    public void Dispose()
+    {
+        lock (_sync) _writer.Dispose();
+    }
+}