using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Test_ReplaceVariable.git
{
    public partial class Form1 : Form
    {
        #region Version und Copyright
        // Version und Copyright
        string programName = Assembly.GetExecutingAssembly().GetCustomAttribute<AssemblyTitleAttribute>().Title; //Den Programmnamen auslesen
        string programVersion = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString();
        static object[] attributes = Assembly.GetExecutingAssembly().GetCustomAttributes(typeof(AssemblyCopyrightAttribute), false);
        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);
                }

                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 Programm-Info
        /// <summary>
        /// Contains the name of the program file
        /// </summary>
        public static string ProgramName { set; get; }

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

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

        private void SetProgramInfo()
        {
            //Name, Version und Copyright setzen
            ProgramName = programName;
            ProgramVersion = programVersion;
            Copyright = copyright;
        }
        #endregion
        public Form1()
        {
            SetProgramInfo();
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            labelVersion.Text = ProgramName + "\nVersion " + ProgramVersion + "\n" + Copyright;
            
            SetEnv();

            labelBefor.Text = text;

            string text1 = ReplaceVarWithValueInString(text);

            if (text1 != null)
            {
                labelAfter.Text = text1;
            }
            else
            {
                labelAfter.Text = "Umgebungsvariable nicht gefunden";
            }
        }

        private void SetEnv()
        {
            Environment.SetEnvironmentVariable("Env_Test1", "Umgebungsvariablen");
            Environment.SetEnvironmentVariable("Env_Test2", "Text");
            Environment.SetEnvironmentVariable("Env_Test3", "ersetzt");
            //Environment.SetEnvironmentVariable("Env_Test4", "einiges");
        }

        const string text = "Das ist ein Text mit %Env_Test1%, welche in einem ${Env_Test2} vorkommen und %Env_Test3% werden sollen. Dabei kann ${Env_Test4} passieren.";

        /// <summary>
        /// Replaces the variables with the pattern ${variable} and/or %variable% in a text with the corresponding value
        /// </summary>
        /// <param name="text">The environment variable containing text. If a variable was not found, then the variable name is not replaced.</param>
        /// <returns>The new string if successful, otherwise 'null'.</returns>
        public static string ReplaceVarWithValueInString(string text)
        {
            if (text.Contains("${") || text.Contains("%"))
            {
                while (text != null && text.Contains("${"))
                {
                    text = ReplaceVarible(text, "${", "}");
                }

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

            return text;
        }

        private static string ReplaceVarible(string text, string startSign, string endSign)
        {
            // Save value before variable
            string temp = text.Remove(text.IndexOf(startSign));

            // Extract variable
            text = text.Remove(0, text.IndexOf(startSign)); // Remove 'temp'
            text = text.Remove(0, startSign.Length); // Remove 'startSign'
            string variableName = text.Remove(text.IndexOf(endSign)); // 'endSign' and remove the following text

            // Create remaining text (behind 'endSign')
            text = text.Remove(0, text.IndexOf(endSign) + 1);

            // Convert variable and reassemble text
            string variable = GetValueFromEnvVar(variableName);

            if (variable != null)
            {
                return temp + variable + text; // Reassemble text
            }
            else
            {
                return null; // Reassemble text, if envvironment varible does not exist
            }
        }

        /// <summary>
        /// Get the value of an environment variable
        /// </summary>
        /// <param name="EnvVarName">Environment variable name</param>
        /// <returns>A string if successful, otherwise 'null'.</returns>
        public static string GetValueFromEnvVar(string EnvVarName)
        {
            if (System.Environment.GetEnvironmentVariable(EnvVarName) == null)
            {
                return null;
            }
            else
            {
                return System.Environment.GetEnvironmentVariable(EnvVarName);
            }
        }
    }
}