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

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

namespace InnovEnergy.App.SaliMax;

public class CustomLogger : ILogger
{
    private readonly String _LogFilePath;
    private readonly Int64  _MaxFileSizeBytes;
    private readonly Int32  _MaxLogFileCount;
    private          Int64  _CurrentFileSizeBytes;

    public CustomLogger(String logFilePath, Int64 maxFileSizeBytes, Int32 maxLogFileCount)
    {
        _LogFilePath          = logFilePath;
        _MaxFileSizeBytes     = maxFileSizeBytes;
        _MaxLogFileCount      = maxLogFileCount;
        _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);
    }
}