Engine.Core/Debug/RotatingFileLogger.cs

@@ -0,0 +1,71 @@
+using System;
+using System.IO;
+using System.Linq;
+
+namespace Engine.Core.Debug;
+
+public class RotatingFileLogger : ILogger
+{
+    public readonly FileLogger FileLogger = null!;
+    public readonly string Directory = string.Empty;
+    public readonly int RotateLength = 3;
+
+    public RotatingFileLogger(string directory, string namePrefix, string nameSuffix = "", int rotateLength = 3)
+    {
+        RotateLength = rotateLength;
+
+        string fileName = Path.Combine(directory, namePrefix);
+        if (!string.IsNullOrWhiteSpace(nameSuffix))
+            fileName += $"_{nameSuffix}";
+
+        bool isRelativePath = Path.GetFullPath(fileName).CompareTo(fileName) != 0;
+
+        if (isRelativePath)
+            fileName = Path.GetFullPath(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, fileName));
+
+        if (File.Exists($"{fileName}.log"))
+            RenameExistingLogs(fileName, RotateLength);
+
+        FileLogger = new(fileName);
+
+        Directory = Path.GetDirectoryName(fileName) ?? throw new("Unexpected error on getting directory of logger path");
+        RotateLastLogs(Directory, namePrefix, RotateLength);
+    }
+
+    private static void RenameExistingLogs(string filePath, int rotateLength)
+    {
+        for (int i = rotateLength - 1; i >= 0; i--)
+        {
+            string source = i == 0
+                ? $"{filePath}.log"
+                : $"{filePath}_{i}.log";
+
+            string dest = $"{filePath}_{i + 1}.log";
+
+            if (!File.Exists(source))
+                continue;
+
+            if (File.Exists(dest))
+                File.Delete(dest);
+
+            File.Move(source, dest);
+        }
+    }
+
+    private static void RotateLastLogs(string directory, string prefix, int rotateLength)
+    {
+        IOrderedEnumerable<string> logs = System.IO.Directory.GetFiles(directory, $"{prefix}*.log")
+            .OrderBy(File.GetCreationTime);
+
+        foreach (string file in logs.Skip(rotateLength))
+            try
+            {
+                ILogger.Shared.Log($"Removing log file located at \"{file}\" during rotation.");
+                File.Delete(file);
+            }
+            catch (Exception e) { ILogger.Shared.LogException($"Failed to rotate log file at \"{file}\"", e); }
+    }
+
+    public ILogger.Level FilterLevel { get => FileLogger.FilterLevel; set => FileLogger.FilterLevel = value; }
+    public void Log(string message, ILogger.Level level = ILogger.Level.Info, bool force = false) => FileLogger.Log(message, level, force);
+}