// Author: Simon Gockner
// Created: 2020-02-08
// Copyright(c) 2020 SimonG. All Rights Reserved.

using System.IO;
using System.Threading;
using System.Threading.Tasks;
using GBase.Logging.Interfaces;

namespace GBase.Logging
{
    /// <summary>
    /// An <see cref="ILogger"/> that writes log messages to a set file
    /// </summary>
    public class FileLogger : IFileLogger
    {
        private readonly StreamWriter _fileWriter;
        private readonly Timer _timer;

        private readonly SemaphoreSlim _lockObject = new SemaphoreSlim(1);

        /// <summary>
        /// Constructor for <see cref="FileLogger"/>
        /// </summary>
        /// <param name="filePath">The directory of the LogFile</param>
        /// <param name="fileName">The path of the LogFile</param>
        public FileLogger(string filePath, string fileName)
        {
            Directory.CreateDirectory(filePath);
            _fileWriter = new StreamWriter(Path.Combine(filePath, fileName), true);
            _timer = new Timer(TimerCallback, null, 0, 1000);
        }

        /// <summary>
        /// Write the given <see cref="string"/> to the file
        /// </summary>
        /// <param name="message">The <see cref="ILogMessage"/></param>
        public async Task Write(ILogMessage message)
        {
            await _lockObject.WaitAsync();
            try
            {
                await _fileWriter.WriteAsync(message.ToString());
            }
            finally
            {
                _lockObject.Release();
            }
        }

        private async void TimerCallback(object state)
        {
            await Flush();
        }

        private async Task Flush()
        {
            await _lockObject.WaitAsync();
            try
            {
                await _fileWriter.FlushAsync();
            }
            finally
            {
                _lockObject.Release();
            }
        }

        /// <summary>
        /// <see cref="DisposeAsync"/> the <see cref="FileLogger"/>
        /// </summary>
        public async ValueTask DisposeAsync()
        {
            _timer.Dispose();

            await Flush();
            _fileWriter.Dispose();

            _lockObject.Dispose();
        }
    }
}