Use filename timestamp for backup ordering and move to Utilities

Source/NETworkManager.Settings/SettingsManager.cs

@@ -180,7 +180,7 @@ public static void Load()
             // Create a backup of the legacy XML file and delete the original
             Backup(legacyFilePath,
                 GetSettingsBackupFolderLocation(),
-                $"{TimestampHelper.GetTimestamp()}_{GetLegacySettingsFileName()}");
+                TimestampHelper.GetTimestampFilename(GetLegacySettingsFileName()));
 
             File.Delete(legacyFilePath);
 
@@ -279,7 +279,7 @@ private static void CreateDailyBackupIfNeeded()
             // Create backup
             Backup(GetSettingsFilePath(),
                 GetSettingsBackupFolderLocation(),
-                $"{TimestampHelper.GetTimestamp()}_{GetSettingsFileName()}");
+                TimestampHelper.GetTimestampFilename(GetSettingsFileName()));
 
             // Cleanup old backups
             CleanupBackups(GetSettingsBackupFolderLocation(),
@@ -295,21 +295,23 @@ private static void CreateDailyBackupIfNeeded()
     /// specified maximum, are retained.
     /// </summary>
     /// <remarks>This method removes the oldest backup files first, keeping only the most recent backups as
-    /// determined by file creation time. It is intended to prevent excessive accumulation of backup files and manage
+    /// determined by the timestamp in the filename. It is intended to prevent excessive accumulation of backup files and manage
     /// disk space usage.</remarks>
     /// <param name="backupFolderPath">The full path to the directory containing the backup files to be managed. Cannot be null or empty.</param>
     /// <param name="settingsFileName">The file name pattern used to identify backup files for cleanup.</param>
     /// <param name="maxBackupFiles">The maximum number of backup files to retain. Must be greater than zero.</param>
     private static void CleanupBackups(string backupFolderPath, string settingsFileName, int maxBackupFiles)
     {
+        // Get all backup files sorted by timestamp (newest first)
         var backupFiles = Directory.GetFiles(backupFolderPath)
-            .Where(f => f.EndsWith(settingsFileName) || f.EndsWith(GetLegacySettingsFileName()))
-            .OrderByDescending(f => File.GetCreationTime(f))
+            .Where(f => (f.EndsWith(settingsFileName) || f.EndsWith(GetLegacySettingsFileName())) && TimestampHelper.IsTimestampedFilename(Path.GetFileName(f)))
+            .OrderByDescending(f => TimestampHelper.ExtractTimestampFromFilename(Path.GetFileName(f)))
             .ToList();
 
         if (backupFiles.Count > maxBackupFiles)
             Log.Info($"Cleaning up old backup files... Found {backupFiles.Count} backups, keeping the most recent {maxBackupFiles}.");
 
+        // Delete oldest backups until the maximum number is reached
         while (backupFiles.Count > maxBackupFiles)
         {
             var fileToDelete = backupFiles.Last();

Source/NETworkManager.Utilities/TimestampHelper.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Globalization;
+using System.IO;
 
 namespace NETworkManager.Utilities;
 
@@ -8,4 +10,48 @@ public static string GetTimestamp()
     {
         return DateTime.Now.ToString("yyyyMMddHHmmss");
     }
+
+    /// <summary>
+    /// Generates a filename by prefixing the specified filename with a timestamp string.
+    /// </summary>
+    /// <param name="fileName">The original filename to be prefixed with a timestamp. Cannot be null or empty.</param>
+    /// <returns>A string containing the timestamp followed by an underscore and the original filename.</returns>
+    public static string GetTimestampFilename(string fileName)
+    {
+        return $"{GetTimestamp()}_{fileName}";
+    }
+
+    /// <summary>
+    /// Determines whether the specified file name begins with a valid timestamp in the format "yyyyMMddHHmmss".
+    /// </summary>
+    /// <remarks>This method checks only the first 14 characters of the file name for a valid timestamp and
+    /// does not validate the remainder of the file name.</remarks>
+    /// <param name="fileName">The file name to evaluate. The file name is expected to start with a 14-digit timestamp followed by an
+    /// underscore and at least one additional character.</param>
+    /// <returns>true if the file name starts with a valid timestamp in the format "yyyyMMddHHmmss"; otherwise, false.</returns>
+    public static bool IsTimestampedFilename(string fileName)
+    {
+        // Ensure the filename is long enough to contain a timestamp, an underscore, and at least one character after it
+        if (fileName.Length < 16)
+            return false;
+
+        var timestampString = fileName.Substring(0, 14);
+
+        return DateTime.TryParseExact(timestampString, "yyyyMMddHHmmss", CultureInfo.InvariantCulture, DateTimeStyles.None, out _);
+    }
+
+    /// <summary>
+    /// Extracts the timestamp from a filename that starts with a timestamp prefix.
+    /// </summary>
+    /// <remarks>Filenames are expected to start with yyyyMMddHHmmss_* format (14 characters). 
+    /// This method extracts the timestamp portion and parses it as a DateTime.</remarks>
+    /// <param name="fileName">The full path to the file or just the filename.</param>
+    /// <returns>The timestamp extracted from the filename.</returns>
+    public static DateTime ExtractTimestampFromFilename(string fileName)
+    {
+        // Extract the timestamp prefix (yyyyMMddHHmmss format, 14 characters)
+        var timestampString = fileName.Substring(0, 14);
+
+        return DateTime.ParseExact(timestampString, "yyyyMMddHHmmss", CultureInfo.InvariantCulture);
+    }
 }