nVLC

//    nVLC
//    
//    Author:  Roman Ginzburg
//
//    nVLC is free software: you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation, either version 3 of the License, or
//    (at your option) any later version.
//
//    nVLC is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
//    GNU General Public License for more details.
//     
// ========================================================================

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using LibVlcWrapper;
using System.Runtime.InteropServices;
using Declarations;
using System.Diagnostics;

namespace Implementation.Loggers
{
    internal unsafe sealed class LogSubscriber : DisposableBase
    {
        private libvlc_log_subscriber m_subscriber;
        private LogCallback m_callback;
        private ILogger m_logger;
        private const int BUFFER_SIZE = 10240;

        public LogSubscriber(ILogger logger)
        {
            m_logger = logger;
            m_callback = OnLogCallback;
            IntPtr hCallback = Marshal.GetFunctionPointerForDelegate(m_callback);
            LibVlcMethods.libvlc_log_subscribe(ref m_subscriber, hCallback, IntPtr.Zero);
        }

        private void OnLogCallback(void* data, libvlc_log_level level, char* fmt, char* args)
        {
            try
            {
                char* buffer = stackalloc char[BUFFER_SIZE];
                int len = vsprintf(buffer, fmt, args);
                string msg = Marshal.PtrToStringAnsi(new IntPtr(buffer), len);

                switch (level)
                {
                    case libvlc_log_level.LIBVLC_DEBUG:
                        m_logger.Debug(msg);
                        break;
                    case libvlc_log_level.LIBVLC_NOTICE:
                        m_logger.Info(msg);
                        break;
                    case libvlc_log_level.LIBVLC_WARNING:
                        m_logger.Warning(msg);
                        break;
                    case libvlc_log_level.LIBVLC_ERROR:
                    default:
                        m_logger.Error(msg);
                        break;
                }
            }
            catch (Exception ex)
            {
                m_logger.Error("Failed to handle log callback, reason : " + ex.Message);
            }
        }

        protected override void Dispose(bool disposing)
        {
            if (m_subscriber.func != IntPtr.Zero)
            {
                LibVlcMethods.libvlc_log_unsubscribe(ref m_subscriber);
            }
            
            if (disposing)
            {
                m_callback = null;
            }
        }

        [DllImport("msvcrt", SetLastError = true, CallingConvention = CallingConvention.Cdecl)]
        private static extern int vsprintf(char* str, char* format, char* arg);
    }
}