using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace Eugen.ESystem.IO
{
    /// <summary>
    /// Handles a log file
    /// </summary>
    [Description("Handles a log file")]
    public class LogWriter : Component
    {
        #region Version und Copyright
        // Version und Copyright
        static string dllName = System.IO.Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase); //Den Programmnamen auslesen
        static string dllVersion = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString();
        static object[] attributes = Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(AssemblyCopyrightAttribute), false);
        static string copyright = GenerateCopyright();

        //Assembly Datum und Zeit
        static DateTime value = AssemblyDateTime();
        static string date = value.ToShortDateString();
        static string time = value.ToLongTimeString();

        private static DateTime AssemblyDateTime()
        {
            var version = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version;
            var buildDateTime = new DateTime(2000, 1, 1).Add(new TimeSpan(TimeSpan.TicksPerDay * version.Build + TimeSpan.TicksPerSecond * 2 * version.Revision));
            //Tage seit dem 1. Januar 2000 und Sekunden seit Mitternacht, (multiplizier mit 2 ergibt das Original)
            return buildDateTime;
        }

        private static string CurrentYear()
        {
            DateTime dtn = DateTime.Now;
            return dtn.Year.ToString();
        }

        private static string StartYear()
        {
            string startYear = "";
            if (((AssemblyCopyrightAttribute)attributes[0]).Copyright.Contains("Copyright © "))
            {
                startYear = ((AssemblyCopyrightAttribute)attributes[0]).Copyright.Replace("Copyright © ", "");
                while (startYear.StartsWith(" "))
                {
                    startYear = startYear.Remove(0, 1);
                }

                if (startYear.Contains("-"))
                {
                    startYear = startYear.Remove(startYear.IndexOf("-"));
                }
                else
                {
                    startYear = startYear.Remove(startYear.IndexOf(" "));
                }
                return startYear;
            }
            else
            {
                DateTime dtn = DateTime.Now;
                return dtn.Year.ToString();
            }
        }

        private static string GenerateCopyright()
        {
            string startYear = StartYear();
            string currentYear = CurrentYear();

            if (startYear == currentYear)
            {
                return ((AssemblyCopyrightAttribute)attributes[0]).Copyright;
            }
            else
            {
                string temp = ((AssemblyCopyrightAttribute)attributes[0]).Copyright;
                string start = temp.Remove(temp.IndexOf(startYear) - 1);
                string end = (temp.Remove(0, temp.IndexOf(" by")));

                return String.Concat(start, " ", startYear, "-", currentYear, end);
            }
        }
        #endregion

        #region DLL-Info
        /// <summary>
        /// Contains the name of the dll file.
        /// </summary>
        public static string DllName { private set; get; }

        /// <summary>
        /// Contains the version of the dll file.
        /// </summary>
        public static string DllVersion { private set; get; }

        /// <summary>
        /// Contains the copyright notice.
        /// </summary>
        public static string Copyright { private set; get; }

        /// <summary>
        /// Contains the name-, version- and copyright-information of the dll file.
        /// </summary>
        public static string[] DllInfo { private set; get; }

        private static void SetDllInfo()
        {
            //Name, Version und Copyright setzen
            DllName = dllName;
            DllVersion = dllVersion;
            Copyright = copyright;

            string[] dllInfo = new string[3];
            dllInfo[0] = dllName;
            dllInfo[1] = dllVersion;
            dllInfo[2] = copyright;
            DllInfo = dllInfo;
        }

        protected string ProgramName { private set; get; }
        protected string ProgramVersion { private set; get; }
        protected string ProgramCopyright { private set; get; }
        #endregion

        #region delegates
        /// <summary>
        /// Provides a method, wich handles events from written messages
        /// </summary>
        /// <param name="sender">Sender object</param>
        /// <param name="e">Event arguments</param>
        [Description("Provides a method, wich handles events from written messages")]
        public delegate void LogWriterEventHandler(object sender, LogWriterEventArgs e);
        #endregion

        #region fields
        /// <summary>
        /// Stores the log save path
        /// </summary>
        private string path = String.Empty;

        /// <summary>
        /// Stores the logfile name
        /// </summary>
        private string filename = String.Empty;

        /// <summary>
        /// Stores the log header
        /// </summary>
        private string logheader = String.Empty;

        /// <summary>
        /// Stores the file name format
        /// </summary>
        private string fileFormat = "log_{0:d}.log";

        /// <summary>
        /// Stores the message format
        /// </summary>
        private string messageFormat = "{0:T}.{1} - {2}";
        #endregion

        #region events
        /// <summary>
        /// Fired, when a message was written
        /// </summary>
        [Description("Fired, when a message was written")]
        public event LogWriterEventHandler MessageWritten;

        /// <summary>
        /// Fired, when a new log file was created. Fired, when a message was written
        /// </summary>
        [Description("Fired, when a new log file was created. Fired, when a message was written")]
        public event EventHandler FileCreated;
        #endregion

        #region properties
        /// <summary>
        /// Specifyes the log save path
        /// </summary>
        [Description("Specifyes the log save path")]
        public string Path
        {
            get
            {
                return this.path;
            }
            set
            {
                this.path = value;
            }
        }

        /// <summary>
        /// Specifyes the file name format
        /// </summary>
        [Description("Specifyes the file name format")]
        [DefaultValue("log_{0:d}.log")]
        public string FileFormat
        {
            get
            {
                return this.fileFormat;
            }
            set
            {
                this.fileFormat = value;
            }
        }

        /// <summary>
        /// Specifyes the message format
        /// </summary>
        [Description("Specifyes the message format")]
        [DefaultValue("{0:t}: {1}")]
        public string MessageFormat
        {
            get
            {
                return this.messageFormat;
            }
            set
            {
                this.messageFormat = value;
            }
        }
        #endregion

        #region constructor
        /// <summary>
        /// Constructor (for DLL-Information)
        /// </summary>
        static LogWriter()
        {
            SetDllInfo();
        }

        /// <summary>
        /// Constructor
        /// </summary>
        public LogWriter()
        {
        }

        /// <summary>
        /// Constructor (Filename = 'log_dd.mm.yyyy.log)
        /// </summary>
        /// <param name="path">Specifyes the log save path</param>
        public LogWriter(string path)
        {
            this.path = path;
        }

        /// <summary>
        /// Constructor (Filename = self defined)
        /// </summary>
        /// <param name="path">Specifyes the log save path</param>
        /// <param name="filename">Specifyes the log file name</param>
        public LogWriter(string path, string filename)
        {
            this.path = path; 
            this.filename = filename;
            if (this.filename.EndsWith(".log"))
            {
                this.filename.Replace(".log", "");
            }
        }

        /// <summary>
        /// Constructor (Filename = self defined, with fileheader)
        /// </summary>
        /// <param name="path"></param>
        /// <param name="filename"></param>
        /// <param name="fileheader"></param>
        public LogWriter(string path, string filename, string logheader)
        {
            this.path = path;
            this.filename = filename;
            if (this.filename.EndsWith(".log"))
            {
                this.filename.Replace(".log", "");
            }
            this.logheader = logheader;
        }
        #endregion

        #region public members
        /// <summary>
        /// Writes a message
        /// </summary>
        /// <param name="message">Specifyes the message to be written</param>
        /// <returns>Wheather the writing progress was successful</returns>
        public bool WriteMessage(string message)
        {
            // if directory not exists, cancel
            if (!Directory.Exists(this.path))
                throw new DirectoryNotFoundException(AppResources.msg001);

            // holds the actual date and time
            DateTime time = DateTime.Now;
            int ms = time.Millisecond;

            // creates the file name
            string fileName;

            if (String.IsNullOrEmpty(this.filename))
            {
                if (String.IsNullOrEmpty(this.path))
                {
                    fileName = System.IO.Path.DirectorySeparatorChar.ToString();
                }
                else
                {
                    fileName = this.path;

                    if (fileName[fileName.Length - 1] != System.IO.Path.DirectorySeparatorChar)
                    {
                        fileName += System.IO.Path.DirectorySeparatorChar;
                    }
                }

                try
                {
                    fileName += String.Format(this.fileFormat, time);
                }
                catch (FormatException)
                {
                    throw new FormatException(AppResources.msg002);
                }
                catch
                {
                    return false;
                }
            }
            else
            {
                if (this.path[this.path.Length - 1] != System.IO.Path.DirectorySeparatorChar)
                {
                    if (String.IsNullOrEmpty(System.IO.Path.GetExtension(this.filename)))
                    {
                        fileName = String.Concat(path, System.IO.Path.DirectorySeparatorChar, this.filename, ".log");
                    }
                    else
                    {
                        fileName = String.Concat(path, System.IO.Path.DirectorySeparatorChar, this.filename);
                    }
                }
                else
                {
                    if (String.IsNullOrEmpty(System.IO.Path.GetExtension(this.filename)))
                    {
                        fileName = String.Concat(this.path, this.filename, ".log");
                    }
                    else
                    {
                        fileName = String.Concat(this.path, this.filename);
                    }
                }
            }

            // build message line
            string line;
            try
            {
                // creates the line
                line = String.Format(this.messageFormat, new object[] { time, ms, message });
            }
            catch (FormatException)
            {
                throw new FormatException(AppResources.msg002);
            }
            catch
            {
                return false;
            }

            try
            {
                StreamWriter writer;

                // if a log header is to be written
                if (!String.IsNullOrEmpty(logheader) && IsFileEmpty(fileName))
                {
                    // write log header
                    // open file
                    if (!File.Exists(fileName))
                    {
                        writer = new StreamWriter(fileName);
                        OnFileCreated(EventArgs.Empty);
                    }
                    else
                        writer = new StreamWriter(fileName);

                    // write message line
                    writer.WriteLine(this.logheader);

                    // close file
                    writer.Close();
                }

                // open file
                if (!File.Exists(fileName))
                {
                    writer = new StreamWriter(fileName);
                    OnFileCreated(EventArgs.Empty);
                }
                else
                    writer = new StreamWriter(fileName, true);
                
                // write message line
                writer.WriteLine(line);

                // close file
                writer.Close();

                OnMessageWritten(new LogWriterEventArgs(time, ms, message));

                return true;
            }
            catch
            {
                return false;
            }
        }

        private bool IsFileEmpty(string filename)
        {
            if (File.Exists(filename))
            {
                System.IO.StreamReader file = new System.IO.StreamReader(filename);

                if (String.IsNullOrEmpty(file.ReadLine()))
                {
                    file.Close();
                    return true; // file is empty
                }
                else
                {
                    file.Close();
                    return false; // file is not empty
                }
            }
            else
            {
                return true; // file doesn't exist - is empty
            }
        }
        #endregion

        #region protected members
        /// <summary>
        /// Fires the MessageWritten event
        /// </summary>
        /// <param name="e"></param>
        protected void OnMessageWritten(LogWriterEventArgs e)
        {
            if (MessageWritten != null)
                MessageWritten(this, e);
        }

        /// <summary>
        /// Fires the FileCreated event
        /// </summary>
        /// <param name="e"></param>
        protected void OnFileCreated(EventArgs e)
        {
            if (FileCreated != null)
                FileCreated(this, e);
        }
        #endregion
    }

    #region LogWriterEventArgs class
    /// <summary>
    /// LogWriterEventArgs stores information about the sent log message
    /// </summary>
    public class LogWriterEventArgs : EventArgs
    {
        #region fields
        /// <summary>
        /// Stores the message post time
        /// </summary>
        private DateTime time;

        /// <summary>
        /// Stores the milliseconds of the post time of the message
        /// </summary>
        private int millisecond;

        /// <summary>
        /// Stores the message
        /// </summary>
        private string message;
        #endregion

        #region properties
        /// <summary>
        /// Specifyes the message post time
        /// </summary>
        [Description("Specifyes the message post time")]
        public DateTime Time
        {
            get
            {
                return this.time;
            }
        }

        /// <summary>
        /// Specifyes the message
        /// </summary>
        [Description("Specifyes the message")]
        public string Message
        {
            get
            {
                return this.message;
            }
        }
        #endregion

        #region constructor
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="time">Specifyes the message post time</param>
        /// <param name="message">Specifyes the message</param>
        public LogWriterEventArgs(DateTime time, int millisecond, string message)
            : base()
        {
            this.time = time;
            this.millisecond = millisecond;
            this.message = message;
        }
        #endregion
    }
    #endregion
}