using System;
using System.Diagnostics;
using System.IO;
using System.Reflection;
using static Eugen.ESystem.IO.LogWriter;

namespace Eugen.ESystem.IO
{
    public class LogWriter
    {
        #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

        /// <summary>
        /// Defines whether and what type of header should/should not be generated
        /// </summary>
        public enum Header
        {
            None,
            Default,
            Userdefined
        }

        /// <summary>
        /// Defines whether the current time should be written or not
        /// </summary>
        public enum Time
        {
            Write,
            NoWrite
        }

        /// <summary>
        /// Defines whether a logging level should be specified or not
        /// </summary>
        public enum LogLevel
        {
            Debugging,
            Information,
            Warning,
            Error,
            Fatal,
            NoLevel
        }

        static LogWriter()
        {
            SetDllInfo();
        }

        public LogWriter(string path)
        {
            SetDllInfo();
            SetDate();
            this.Path = path;
            this.FileName = String.Concat("log_", this.CurrentDate, ".log");
        }

        public LogWriter(string path, string fileName)
        {
            SetDllInfo();
            SetDate();
            this.Path = path;
            if (fileName.EndsWith(".log"))
            {
                this.FileName = fileName;
            }
            else
            {
                this.FileName = String.Concat(fileName, ".log");
            }
        }

        private string Path { get; set; }
        private string FileName { get; set; }
        private string CurrentDate { get; set; }
        private string MessageFormat
        {
            get
            {
                return this.messageFormat;
            }
            set
            {
                this.messageFormat = value;
            }
        }

        private void SetDate()
        {
            DateTime dateTime = DateTime.Now;
            this.CurrentDate = dateTime.ToString().Remove(dateTime.ToString().IndexOf(" "));
        }

        private string messageFormat = "{0}{1:T}.{2} - {3}"; // Definiert das Mitteilungsformat

        /// <summary>
        /// Name of the program to be logged
        /// </summary>
        public string NameOfProgram { get; set; }

        /// <summary>
        /// Version number of the program to be logged
        /// </summary>
        public string VersionNumberOfProgram { get; set; }

        /// <summary>
        /// Copyright of the program to be logged
        /// </summary>
        public string CopyrightOfProgram { get; set; }

        /// <summary>
        /// Content of a self-defined header as a string
        /// </summary>
        public string UserDefinedHeaderAsString { get; set; }

        /// <summary>
        /// Content of a self-defined header as a string array
        /// </summary>
        public string[] UserDefinedHeaderAsArray { get; set; }

        /// <summary>
        /// Writes a separation line to a log file
        /// </summary>
        /// <returns>On success true is returned, on the other hand false</returns>
        public bool WriteSeparationLine()
        {
            string message = String.Empty;
            return WriteMessage(message.PadRight(80, '-'), LogLevel.NoLevel, Time.NoWrite);
        }

        /// <summary>
        /// Writes a header to a log file
        /// </summary>
        /// <param name="header"></param>
        /// <returns>On success true is returned, on the other hand false</returns>
        public bool WriteHeader(Header header)
        {
            switch (header)
            {
                case Header.Default:
                    return WriteDefaultHeader();
                case Header.Userdefined:
                    if (!String.IsNullOrEmpty(UserDefinedHeaderAsString))
                    {
                        return WriteUserDefinedHeader(DefineUserDefinedHeader());
                    }
                    else if (UserDefinedHeaderAsArray != null)
                    {
                        return WriteUserDefinedHeader(UserDefinedHeaderAsArray);
                    }
                    else
                    {
                        return false;
                    }
                case Header.None:
                    return true;
                default:
                    return true;
            }
        }

        private bool WriteDefaultHeader()
        {
            string message = String.Empty;
            string line = message.PadRight(80, '-');

            try
            {
                StreamWriter writer;

                if (!File.Exists(String.Concat(this.Path, "\\", this.FileName)))
                {
                    // Wenn Logdatei noch nicht existiert, dann anlegen
                    writer = new StreamWriter(String.Concat(this.Path, "\\", this.FileName));
                    OnFileCreated(EventArgs.Empty);
                }
                else
                {
                    // Wenn Logdatei schon existiert, dann zum Schreiben öffnen
                    writer = new StreamWriter(String.Concat(this.Path, "\\", this.FileName), true);
                }

                // Zeile schreiben
                writer.WriteLine(line);
                writer.WriteLine(DefaultHeaderLine1());
                writer.WriteLine(DefaultHeaderLine2());
                writer.WriteLine(DefaultHeaderLine3());
                writer.WriteLine(CurrentDayDateTime());
                writer.WriteLine(line);

                // Logdatei schließen
                writer.Close();

                OnMessageWritten(new LogWriterEventArgs(LogLevel.NoLevel.ToString(), DateTime.Now, 0, "SUCCESS"));

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        private string DefaultHeaderLine1()
        {
            if (String.IsNullOrEmpty(NameOfProgram))
            {
                return "Program Name:";
            }
            else
            {
                return String.Concat("Program Name:    ", NameOfProgram);
            }
        }

        private string DefaultHeaderLine2()
        {
            if (String.IsNullOrEmpty(VersionNumberOfProgram))
            {
                return "Program Version: ";
            }
            else
            {
                return String.Concat("Program Version: ", VersionNumberOfProgram);
            }
        }

        private string DefaultHeaderLine3()
        {
            if (String.IsNullOrEmpty(CopyrightOfProgram))
            {
                return "Copyright:       ";
            }
            else
            {
                if(CopyrightOfProgram.StartsWith("Copyright"))
                {
                    return String.Concat("Copyright:       ", CopyrightOfProgram.Remove(0, CopyrightOfProgram.IndexOf(" ") + 1));
                }
                else
                {
                    return String.Concat("Copyright:       ", CopyrightOfProgram);
                }
            }
        }

        private string[] DefineUserDefinedHeader()
        {
            if (!String.IsNullOrEmpty(UserDefinedHeaderAsString))
            {
                string[] stringSeparators = new string[] { "\n\r", "\r\n", "\n", "\r" };
                string[] lines = UserDefinedHeaderAsString.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries);

                return lines;
            }
            else
            {
                string[] lines = {" "};
                return lines;
            }
        }

        private bool WriteUserDefinedHeader(string[] lines)
        {
            string message = String.Empty;
            string line = message.PadRight(80, '-');

            try
            {
                StreamWriter writer;

                if (!File.Exists(String.Concat(this.Path, "\\", this.FileName)))
                {
                    // Wenn Logdatei noch nicht existiert, dann anlegen
                    writer = new StreamWriter(String.Concat(this.Path, "\\", this.FileName));
                    OnFileCreated(EventArgs.Empty);
                }
                else
                {
                    // Wenn Logdatei schon existiert, dann zum Schreiben öffnen
                    writer = new StreamWriter(String.Concat(this.Path, "\\", this.FileName), true);
                }

                // Zeilen schreiben
                writer.WriteLine(line);

                for (int i = 0; i < lines.Length; i++)
                {
                    writer.WriteLine(lines[i]);
                }

                writer.WriteLine(line);

                // Logdatei schließen
                writer.Close();

                OnMessageWritten(new LogWriterEventArgs(LogLevel.NoLevel.ToString(), DateTime.Now, 0, "SUCCESS"));

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        /// <summary>
        /// Writes the current day, date and time to a logfile
        /// </summary>
        /// <returns>On success true is returned, on the other hand false</returns>
        public bool WriteDayDateTime()
        {
            try
            {
                StreamWriter writer;

                if (!File.Exists(String.Concat(this.Path, "\\", this.FileName)))
                {
                    // Wenn Logdatei noch nicht existiert, dann anlegen
                    writer = new StreamWriter(String.Concat(this.Path, "\\", this.FileName));
                    OnFileCreated(EventArgs.Empty);
                }
                else
                {
                    // Wenn Logdatei schon existiert, dann zum Schreiben öffnen
                    writer = new StreamWriter(String.Concat(this.Path, "\\", this.FileName), true);
                }

                // Zeile schreiben
                writer.WriteLine(CurrentDayDateTime());

                // Logdatei schließen
                writer.Close();

                OnMessageWritten(new LogWriterEventArgs(LogLevel.NoLevel.ToString(), DateTime.Now, 0, "SUCCESS"));

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        private string CurrentDayDateTime()
        {
            DateTime time = DateTime.Now;
            int ms = time.Millisecond;

            return String.Concat("Date:            ", time.DayOfWeek.ToString(), ", ", time, ".", ms.ToString("000"));
        }

        /// <summary>
        /// Writes a message to a log file
        /// </summary>
        /// <param name="message">The message to write</param>
        /// <returns>On success true is returned, on the other hand false</returns>
        public bool WriteMessage(string message)
        {
            return WriteMessage(message, LogLevel.NoLevel, Time.Write);
        }

        /// <summary>
        /// Writes a message to a log file
        /// </summary>
        /// <param name="message">The message to write</param>
        /// <param name="writeLogLevel">Writes the log level in front of the line</param>
        /// <param name="writeTime">Writes the log time</param>
        /// <returns>On success true is returned, on the other hand false</returns>
        public bool WriteMessage(string message, LogLevel writeLogLevel, Time writeTime)
        {
            string logLevel = "";

            switch (writeLogLevel)
            {
                case LogLevel.Debugging:
                    logLevel = "DEBUG - ";
                    break;
                case LogLevel.Information:
                    logLevel = "INFO  - ";
                    break;
                case LogLevel.Warning:
                    logLevel = "WARN  - ";
                    break;
                case LogLevel.Error:
                    logLevel = "ERROR - ";
                    break;
                case LogLevel.Fatal:
                    logLevel = "FATAL - ";
                    break;
                case LogLevel.NoLevel:
                    logLevel = "";
                    break;
                default:
                    logLevel = "";
                    break;
            }

            DateTime time = DateTime.Now;
            int ms = time.Millisecond;

            if (writeTime == Time.Write)
            {
                return WriteLine(logLevel, time, ms, String.Format(this.messageFormat, new object[] { logLevel, time, ms.ToString("000"), message }));
            }
            else
            {
                return WriteLine(logLevel, time, ms, message);
            }
        }

        private bool WriteLine(string logLevel, DateTime time, int ms, string message)
        {
            try
            {
                StreamWriter writer;

                if (!File.Exists(String.Concat(this.Path, "\\", this.FileName)))
                {
                    // Wenn Logdatei noch nicht existiert, dann anlegen
                    writer = new StreamWriter(String.Concat(this.Path, "\\", this.FileName));
                    OnFileCreated(EventArgs.Empty);
                }
                else
                {
                    // Wenn Logdatei schon existiert, dann zum Schreiben öffnen
                    writer = new StreamWriter(String.Concat(this.Path, "\\", this.FileName), true);
                }

                // Zeile schreiben
                writer.WriteLine(message);

                // Logdatei schließen
                writer.Close();

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

                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        /// <summary>
        /// Displays the current logfile
        /// </summary>
        /// <returns>Wheather the displaying progress was successful</returns>
        public bool ShowLogFile()
        {
            return ShowLogFile(this.Path, this.FileName);
        }

        /// <summary>
        /// Displays a logfile
        /// </summary>
        /// <param name="path">A valid path</param>
        /// <param name="fileName">A valid filename</param>
        /// <returns>Wheather the displaying progress was successful</returns>
        public bool ShowLogFile(string path, string fileName)
        {
            if (String.IsNullOrEmpty(path) || String.IsNullOrEmpty(fileName))
            {
                return false; // Pfad oder Name wurde nicht gefunden
            }
            else
            {
                if (File.Exists(String.Concat(path, "\\", fileName)))
                {
                    try
                    {
                        //Aufruf mit dem Standardprogramm
                        var process = new Process();
                        process.StartInfo = new ProcessStartInfo()
                        {
                            UseShellExecute = true,
                            FileName = String.Concat(path, "\\", fileName)
                        };

                        process.Start();
                        process.WaitForExit();
                        return true;
                    }
                    catch (Exception)
                    {
                        try
                        {
                            const string program = "Notepad.exe"; //Aufruf mit Notepad

                            ProcessStartInfo start = new ProcessStartInfo(program, String.Concat(path, "\\", fileName));
                            Process.Start(start);
                            return true;
                        }
                        catch (Exception)
                        {
                            return false;
                        }
                    }
                }
                else
                {
                    return false;
                }
            }
        }

        /// <summary>
        /// Deletes the current Logfile
        /// </summary>
        /// <returns>Wheather the deleting progress was successful</returns>
        public bool Delete()
        {
            try
            {
                if  (String.IsNullOrEmpty(Path) || String.IsNullOrEmpty(FileName))
                {
                    return false;
                }

                if (!File.Exists(String.Concat(this.Path, "\\", this.FileName)))
                {
                    return true; // Existiert nicht mehr
                }
                else
                {
                    // Muss noch gelöscht werden
                    File.Delete(String.Concat(this.Path, "\\", this.FileName));

                    if (File.Exists(String.Concat(this.Path, "\\", this.FileName)))
                    {
                        return false; // Konnte nicht gelöscht werden
                    }
                    else
                    {
                        return true; // Wurde erfolgreich gelöscht
                    }
                }
            }
            catch (Exception)
            {
                return false;
            }
        }

        public bool Delete(string path, string fileName)
        {
            if (!fileName.EndsWith(".log"))
            {
                fileName = String.Concat(fileName, ".log");
            }

            try
            {
                if (File.Exists(String.Concat(path, "\\", fileName)))
                {
                    File.Delete(String.Concat(path, "\\", fileName));

                    if (File.Exists(String.Concat(path, "\\", fileName)))
                    {
                        return false; // Konnte nicht gelöscht werden
                    }
                    else
                    {
                        return true; // Wurde erfolgreich gelöscht
                    }
                }
                else
                {
                    return true; // Existiert nicht mehr
                }
            }
            catch (Exception)
            {
                return false;
            }
        }

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

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

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

        /// <summary>
        /// Fired, when a new log file was created. Fired, when a message was written
        /// </summary>
        public event EventHandler FileCreated;

        /// <summary>
        /// Fired, when a message was written
        /// </summary>
        public event LogWriterEventHandler MessageWritten;
    }

    /// <summary>
    /// LogWriterEventArgs stores information about the sent log message
    /// </summary>
    public class LogWriterEventArgs : EventArgs
    {
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="time">Specifyes the message post time</param>
        /// <param name="millisecond">Specifyes the message post milliseconds</param>
        /// <param name="message">Specifyes the message</param>
        public LogWriterEventArgs(string logLevel, DateTime time, int millisecond, string message) : base()
        {
            this.logLevel = logLevel;
            this.time = time;
            this.millisecond = millisecond;
            this.message = message;
        }

        #region fields
        /// <summary>
        /// Stores the logging level
        /// </summary>
        private string logLevel;

        /// <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>
        public DateTime Time
        {
            get
            {
                return this.time;
            }
        }

        /// <summary>
        /// Specifyes the message
        /// </summary>
        public string Message
        {
            get
            {
                return this.message;
            }
        }
        #endregion
    }
}