Innovenergy_trunk/csharp/App/SaliMax/src/Logfile.cs

using InnovEnergy.Lib.Time.Unix;
using Microsoft.Extensions.Logging;

namespace InnovEnergy.App.SaliMax;

public class CustomLogger(String logFilePath, Int64 maxFileSizeBytes, Int32 maxLogFileCount)
    : ILogger
{
    private Int64  _CurrentFileSizeBytes = File.Exists(logFilePath) 
                                         ? new FileInfo(logFilePath).Length 
                                         : 0;

    public IDisposable? BeginScope<TState>(TState state) where TState : notnull => throw new NotImplementedException();

    public Boolean IsEnabled(LogLevel logLevel) => true; // Enable logging for all levels

    public void Log<TState>(LogLevel logLevel, 
                             EventId eventId, 
                              TState state, 
                          Exception? exception, 
     Func<TState, Exception, String> formatter)
    {
        var logMessage = formatter(state, exception!);

        // Check the file size and rotate the log file if necessary
        if (_CurrentFileSizeBytes + logMessage.Length >= maxFileSizeBytes)
        {
            RotateLogFile();
            _CurrentFileSizeBytes = 0;
        }

        // Write the log message to the file
        File.AppendAllText(logFilePath, logMessage + Environment.NewLine);
        _CurrentFileSizeBytes += logMessage.Length;
        
        Console.WriteLine(logMessage);
    }

    private void RotateLogFile()
    {
        // Check the log file count and delete the oldest file if necessary
        var logFileDir      = Path.GetDirectoryName(logFilePath)!;
        var logFileExt      = Path.GetExtension(logFilePath);
        var logFileBaseName = Path.GetFileNameWithoutExtension(logFilePath);

        var logFiles = Directory
                      .GetFiles(logFileDir, $"{logFileBaseName}_*{logFileExt}")
                      .OrderBy(file => file)
                      .ToList();

        if (logFiles.Count >= maxLogFileCount)
            File.Delete(logFiles.First());

        // Rename the current log file with a timestamp
        var logFileBackupPath = Path.Combine(logFileDir, $"{logFileBaseName}_{UnixTime.Now}{logFileExt}");
        File.Move(logFilePath, logFileBackupPath);
    }
}