using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Resources;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Eugen.ESystem
{
    public class ReplaceVariableByValue
    {
        #region Version und Copyright
        // Version und Copyright
        static string dllName = 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();
        string icon = Application.StartupPath + "\\Info.bmp";
        //Assembly Datum und Zeit
        static DateTime value = AssemblyDateTime();
        string date = value.ToShortDateString();
        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);
                }
                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
            {
                return ((AssemblyCopyrightAttribute)attributes[0]).Copyright.Replace(startYear, String.Concat(startYear, "-", currentYear));
            }
        }
        #endregion

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

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

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

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

        /// <summary>
        /// Replaces a Environment variable through the variable value.
        /// </summary>
        static ReplaceVariableByValue()
        {
            SetDllInfo(); //Name, Version und Copyright der DLL setzen
        }

        const string repStart = "<§<§<§<";
        const string repEnd = ">§>§>§>";

        /// <summary>
        /// Replaces variables with the pattern ${variable} or %variable% with their value.
        /// </summary>
        /// <param name="text">The environment variable containing text. If a variable was not found, then the variable name is not replaced.</param>
        /// <returns>The edited text.</returns>
        public static string Replace(string text)
        {
            if (!(text.Contains("${") || text.Contains("%")) || String.IsNullOrEmpty(text))
            {
                return text;
            }

            while (text.Contains("${"))
            {
                text = ReplaceVarible(text, "${", "}");
            }

            //Wenn die Umgebungsvariable nicht gefunden wurde, dann die Ursprüngliche Umgebungsvariable wieder herstellen
            if (text.Contains(repStart))
            {
                text.Replace(repStart, "${");
                text.Replace(repEnd, "}");
            }

            while (text.Contains("%"))
            {
                text = ReplaceVarible(text, "%", "%");
            }

            //Wenn die Umgebungsvariable nicht gefunden wurde, dann die Ursprüngliche Umgebungsvariable wieder herstellen
            if (text.Contains(repStart))
            {
                text = text.Replace(repStart, "%");
                text = text.Replace(repEnd, "%");
            }

            return text;
        }

        /// <summary>
        /// Replaces variables with the pattern ${variable} or %variable% with their value.
        /// </summary>
        /// <param name="text">The environment variable containing text.</param>
        /// <param name="messageWhenError">Behavior if variable was not found. True=An exception is thrown. False=The variable is not replaced.</param>
        /// <returns>The edited text</returns>
        public static string Replace(string text, bool messageWhenError)
        {
            if ((!text.Contains("${") && !text.Contains("%")) || String.IsNullOrEmpty(text))
            {
                return text;
            }

            while (text.Contains("${"))
            {
                text = ReplaceVarible(text, "${", "}");
            }

            //Wenn die Umgebungsvariable nicht gefunden wurde, dann die Ursprüngliche Umgebungsvariable wieder herstellen
            if (text.Contains(repStart))
            {
                if (messageWhenError)
                {
                    string varName = text.Remove(0, text.IndexOf(repStart) + 7);
                    varName = varName.Remove(varName.IndexOf(repEnd));

                    text.Replace(repStart, "${");
                    text.Replace(repEnd, "}");

                    throw new NoEnvironmentVariableFoundException(String.Concat(Language.message001seg01, varName, Language.message001seg02));
                }
                else
                {
                    text.Replace(repStart, "${");
                    text.Replace(repEnd, "}");
                }
            }

            while (text.Contains("%"))
            {
                text = ReplaceVarible(text, "%", "%");
            }

            //Wenn die Umgebungsvariable nicht gefunden wurde, dann die Ursprüngliche Umgebungsvariable wieder herstellen
            if (text.Contains(repStart))
            {
                if (messageWhenError)
                {
                    string varName = text.Remove(0, text.IndexOf(repStart) + 7);
                    varName = varName.Remove(varName.IndexOf(repEnd));

                    text = text.Replace(repStart, "%");
                    text = text.Replace(repEnd, "%");

                    throw new NoEnvironmentVariableFoundException(String.Concat(Language.message001seg01, varName, Language.message001seg02));
                }
                else
                {
                    text = text.Replace(repStart, "%");
                    text = text.Replace(repEnd, "%");
                }
            }

            return text;
        }

        private static string ReplaceVarible(string text, string startSign, string endSign)
        {
            //Wert vor der Variablen sichern
            string temp = text.Remove(text.IndexOf(startSign));

            //Variable extrahieren
            text = text.Remove(0, text.IndexOf(startSign)); //'temp' entfernen
            text = text.Remove(0, startSign.Length); //'startSign' entfernen
            string variableName = text.Remove(text.IndexOf(endSign)); //'endSign' und nachfolgenden Text entfernen

            //Restlicher Text (hinter 'endSign') erzeugen
            text = text.Remove(0, text.IndexOf(endSign) + 1);

            //Variable umwandeln und Text wieder zusammenbauen
            string variable = ReplaceEnvironmentVariable(variableName);
            text = temp + variable + text; //Text wieder zusammensetzen

            return text;
        }

        private static string ReplaceEnvironmentVariable(string variableName)
        {
            string variableValue = "";

            //Wenn im Text eine bekannte Umgebungsvariable enthalten ist, dann gegen den aktuellen Wert tauschen
            variableValue = Environment.GetEnvironmentVariable(variableName);

            if (String.IsNullOrEmpty(variableValue))
            {
                variableValue = String.Concat(repStart, variableName, repEnd); //Wird keine Umgebungsvariable gefunden, dann wieder den Variblen Namen zurückgeben
            }
                
            return variableValue;
        }
    }

    #region Exceptions
    class NoEnvironmentVariableFoundException : ApplicationException
    {
        public NoEnvironmentVariableFoundException()
        {
        }

        public NoEnvironmentVariableFoundException(string message)
            : base(message)
        {
        }

        public NoEnvironmentVariableFoundException(string message, Exception inner)
            : base(message, inner)
        {
        }
    }
    #endregion
}