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

namespace Tango.Logging
{
    public class SessionFileLogger : ILogger
    {
        private bool _inInSession;
        private int _writeCount;
        private const string FILE_SESSION_EXTENSION = "_session";
        private const int FILE_SIZE_CHECK_COUNT = 100;

        #region Static Properties

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

        #endregion

        #region Properties

        public bool Enabled { get; set; }

        /// <summary>
        /// Folder is used for save file session logs
        /// </summary>
        public String Folder { get; private set; }

        /// <summary>
        /// Full path of 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 maximum file size limit.
        /// </summary>
        public long MaxFileSizeLimit { get; set; }

        #endregion

        #region Constructors
        /// <summary>
        /// Initializes the static members of the class.
        /// </summary>
        static SessionFileLogger()
        {
            DefaultLogsFolder = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "Twine", "Tango", "Logs", Path.GetFileNameWithoutExtension(AppDomain.CurrentDomain.FriendlyName), "Session");

        }

        public SessionFileLogger(String folder, String tag)
        {
            Folder = folder;
            Tag = tag;
            Directory.CreateDirectory(Folder);
            Enabled = true;
            _writeCount = 0;
            MaxFileSizeLimit = 1000000 * 10; //10 MB
        }

        public SessionFileLogger() : this(DefaultLogsFolder, Path.GetFileNameWithoutExtension(AppDomain.CurrentDomain.FriendlyName))
        {
        }
        #endregion

        #region Public Methods

        /// <summary>
        /// Creates the session. Only one file should be for session log, so removed old file and create a new file.
        /// </summary>
        public void CreateSession()
        {
            _writeCount = 0;
            RemoveOldLogFile();
            LogFile = CreateLogFileName();
            _inInSession = true;
        }

        /// <summary>
        /// Ends the session. Set flag _inInSession to false.
        /// </summary>
        public void EndSession()
        {
            _inInSession = false;
        }

        /// <summary>
        /// Called when write to session log file.
        /// </summary>
        /// <param name="output">The output.</param>
        public void OnLog(LogItemBase output)
        {
            if (_inInSession)
            {
                try
                {
                    if (!File.Exists(LogFile) || (++_writeCount > FILE_SIZE_CHECK_COUNT && new FileInfo(LogFile).Length > MaxFileSizeLimit))
                    {
                        CreateSession();
                    }

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

        #endregion

        #region Private Methods

        /// <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", DateTime.Now, Tag, FILE_SESSION_EXTENSION));
        }

        /// <summary>
        /// Delete the old log file if is existed.
        /// </summary>
        private void RemoveOldLogFile()
        {
            try
            {
                if (Directory.Exists(Folder))
                {
                    string[] fileEntries = Directory.GetFiles(Folder, "*.log");
                    foreach (string fileName in fileEntries)
                    {
                        try
                        {
                            File.Delete(fileName);
                        }
                        catch (Exception ex)
                        {
                            Debug.WriteLine(ex);
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex);
            }
        }

        #endregion
    }
}