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) 
    {
        throw new NotImplementedException();
    }

    public Boolean IsEnabled(LogLevel logLevel)
    {
        return 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;
    }

    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);
    }
}