using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Eugen.ESystem.IO;

namespace CorrectDateInCopyright
{
    static class CorrectDateInLine
    {
        //public CorrectDateInLine()
        //{
        //}

        static CorrectDateInLine()
        {
        }

        public static string LogFile { set; get; }

        /// <summary>
        /// Corrects the specified file
        /// </summary>
        /// <param name="fullFileName">A valid filename with path and extension.</param>
        public static void Correct(string fullFileName)
        {
            List<string> lines = new List<string>();

            lines = ReadFileLineByLine.Read(fullFileName);

            for (int i = 0; i < lines.Count; i++)
            {
                if (lines[i].Contains("AssemblyCopyright"))
                {
                    lines[i] = SwapDate(lines[i]);
                }
            }

            WriteFile(fullFileName, lines);
        }

        private static string SwapDate(string line)
        {
            var log = new LogWriter(String.Concat(Path.GetDirectoryName(LogFile), "\\"), Path.GetFileName(LogFile));
            log.WriteMessage(String.Concat("  Alter Wert: ", line));

            string startPart = "[assembly: AssemblyCopyright(\"Copyright © ";
            string endPart = " by Eugen Höglinger\")]";
            string startDate = ExtractStartDate(line);

            string currentDate = DateTime.Now.ToString("yyyy");

            //Neu zusammenstellen
            if (startDate == currentDate)
            {
                line = String.Concat(startPart, startDate, endPart);
            }
            else
            {
                line = String.Concat(startPart, startDate, "-", currentDate, endPart);
            }

            log.WriteMessage(String.Concat("  Neuer Wert: ", line));

            return line;
        }

        private static string ExtractStartDate(string text)
        {
            char[] delimiterChars = { ' ', '-' }; //Trennzeichen
            string[] words = text.Split(delimiterChars);
            int year = 0;

            foreach (var word in words)
            {
                //Prüfen ob der Wert eine Zahl ist
                if (int.TryParse(word, out year))
                {
                    break; //Sobald eine Zahl gefunden wurde, dann aufhören
                }
            }

            return year.ToString();
        }

        private static void WriteFile(string fullFileName, List<string> lines)
        {
            //Datei umbenennen
            File.Move(fullFileName, String.Concat(fullFileName, "_old"));

            //Datei schreiben
            StreamWriter writer;
            writer = new StreamWriter(fullFileName, true, Encoding.Default);
            foreach (var item in lines)
            {
                writer.WriteLine(item);
            }

            writer.Close();

            //Umbenannte Datei löschen
            File.Delete(String.Concat(fullFileName, "_old"));
        }
    }
}