using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Threading;

namespace Tango.Logging
{
    /// <summary>
    /// Represents an <see cref="ILogger"/> file logger.
    /// </summary>
    /// <seealso cref="Tango.Logging.ILogger" />
    public class FileLogger : ILogger
    {
        private DateTime _logFileTimeDate;
        private System.Timers.Timer _removal_timer;
        private int _writeCount;
        private int _fileExtensionIndex;
        private const int FILE_SIZE_CHECK_COUNT = 100;
        public const string FILE_SET_EXTENSION = "__";

        /// <summary>
        /// Gets the logs folder.
        /// </summary>
        public static String DefaultLogsFolder { get; private set; }

        /// <summary>
        /// Gets or sets the log file.
        /// </summary>
        public String LogFile { get; private set; }

        /// <summary>
        /// Gets the tag name which will be appended to the file.
        /// </summary>
        public String Tag { get; private set; }

        /// <summary>
        /// Gets or sets the log file folder.
        /// </summary>
        public String Folder { get; private set; }

        /// <summary>
        /// Gets or sets a value indicating whether [enable automatic log removal].
        /// </summary>
        public bool EnableAutoLogRemoval { get; set; }

        /// <summary>
        /// Gets or sets the automatic log removal period.
        /// </summary>
        public TimeSpan AutoLogRemovalPeriod { get; set; }

        private TimeSpan _autoLogRemovalCheckPeriod;
        /// <summary>
        /// Gets or sets the automatic log removal check period.
        /// </summary>
        public TimeSpan AutoLogRemovalCheckPeriod
        {
            get { return _autoLogRemovalCheckPeriod; }
            set
            {
                _autoLogRemovalCheckPeriod = value;

                if (_removal_timer != null)
                {
                    _removal_timer.Interval = _autoLogRemovalCheckPeriod.TotalMilliseconds;
                }
            }
        }

        /// <summary>
        /// Gets or sets a value indicating whether [enable maximum file size limit].
        /// </summary>
        public bool EnableMaxFileSizeLimit { get; set; }

        /// <summary>
        /// Gets or sets the maximum file size limit.
        /// </summary>
        public long MaxFileSizeLimit { get; set; }


        public String GetFileSetExtension(int index)
        {
            return FILE_SET_EXTENSION + index;
        }

        /// <summary>
        /// Initializes the <see cref="FileLogger"/> class.
        /// </summary>
        static FileLogger()
        {
            DefaultLogsFolder = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "Twine", "Tango", "Logs", Path.GetFileNameWithoutExtension(AppDomain.CurrentDomain.FriendlyName));
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="FileLogger"/> class.
        /// </summary>
        /// <param name="folder">Logs folder path.</param>
        /// <param name="tag">The tag name which will be appended to the file name.</param>
        public FileLogger(String folder, String tag)
        {
            _isEnabled = true;

            Tag = tag;
            Folder = folder;
            Directory.CreateDirectory(Folder);
            _logFileTimeDate = DateTime.Now;
            LogFile = CreateLogFileName();

            EnableAutoLogRemoval = false;
            AutoLogRemovalCheckPeriod = TimeSpan.FromHours(1);
            AutoLogRemovalPeriod = TimeSpan.FromDays(7);

            _removal_timer = new System.Timers.Timer();
            _removal_timer.Interval = AutoLogRemovalCheckPeriod.TotalMilliseconds;
            _removal_timer.Elapsed += _removal_timer_Elapsed;
            _removal_timer.Start();

            EnableMaxFileSizeLimit = true;
            MaxFileSizeLimit = 1000000 * 10;
            _fileExtensionIndex = 0;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="FileLogger"/> class.
        /// </summary>
        public FileLogger() : this(DefaultLogsFolder, Path.GetFileNameWithoutExtension(AppDomain.CurrentDomain.FriendlyName))
        {

        }

        /// <summary>
        /// Called when a new library trace is available.
        /// </summary>
        /// <param name="output">The output.</param>
        public void OnLog(LogItemBase output)
        {
            try
            {
                if (DateTime.Now.Date > _logFileTimeDate.Date)
                {
                    _fileExtensionIndex = 0;
                    _writeCount = 0;
                    _logFileTimeDate = DateTime.Now;
                    CreateNewLogFile();
                }
                else if (EnableMaxFileSizeLimit && ++_writeCount > FILE_SIZE_CHECK_COUNT)
                {
                    if (new FileInfo(LogFile).Length > MaxFileSizeLimit)
                    {
                        if (_fileExtensionIndex == 0)
                        {
                            _fileExtensionIndex = 1;
                            string oldPath = LogFile;
                            LogFile = CreateLogFileName();
                            File.Move(oldPath, LogFile);
                        }
                        _fileExtensionIndex++;
                        CreateNewLogFile();
                        _writeCount = 0;
                    }
                }

                File.AppendAllText(LogFile, output.ToString() + Environment.NewLine);
            }
            catch
            {
                Debug.WriteLine("Error Writing To Log File!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
            }
        }

        private bool _isEnabled;
        /// <summary>
        /// Gets or sets a value indicating whether this <see cref="ILogger" /> is enabled.
        /// </summary>
        public bool Enabled
        {
            get
            {
                return _isEnabled;
            }
            set
            {
                _isEnabled = value;
            }
        }

        /// <summary>
        /// Creates the name of the log file.
        /// </summary>
        /// <returns></returns>
        private String CreateLogFileName()
        {
            return Path.Combine(Folder, string.Format("{1}-{0:dd-MM-yyyy_HH-mm-ss}{2}.log", _logFileTimeDate, Tag, EnableMaxFileSizeLimit && _fileExtensionIndex > 0 ? GetFileSetExtension(_fileExtensionIndex) : String.Empty));
        }

        private void CreateNewLogFile()
        {
            File.AppendAllText(LogFile, Environment.NewLine + Environment.NewLine + "### This log file continues on the next log file ###" + Environment.NewLine);
            LogFile = CreateLogFileName();
            File.AppendAllText(LogFile, "### This log file is a continuation of a previous log file ###" + Environment.NewLine + Environment.NewLine);
        }

        #region Auto Log Removal

        /// <summary>
        /// Handles the Elapsed event of the _removal_timer control.
        /// </summary>
        /// <param name="sender">The source of the event.</param>
        /// <param name="e">The <see cref="System.Timers.ElapsedEventArgs"/> instance containing the event data.</param>
        private void _removal_timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
        {
            if (EnableAutoLogRemoval)
            {
                RemoveOldLogFiles();
            }
        }

        /// <summary>
        /// Removes the old files.
        /// </summary>
        public void RemoveOldLogFiles()
        {
            try
            {
                if (Directory.Exists(Folder))
                {
                    DateTime removalDateTime = DateTime.Now - AutoLogRemovalPeriod;
                    string[] fileEntries = Directory.GetFiles(Folder, "*.log");
                    foreach (string fileName in fileEntries)
                    {
                        try
                        {
                            FileInfo fi = new FileInfo(fileName);

                            if (fi != null && fi.LastWriteTime < removalDateTime)
                            {
                                File.Delete(fi.FullName);
                            }
                        }
                        catch (Exception ex)
                        {
                            Debug.WriteLine(ex);
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex);
            }
        }

        #endregion
    }
}