using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Text.RegularExpressions;

namespace vcsConvertor
{
  public partial class Form1 : Form
  {
    bool folderSelected = false;
    bool fileSelected = false;
    public Form1()
    {
      InitializeComponent();
      saveFileDialog1.Filter = "*.csv|*.csv";
    }

    private void btSelectFolder_Click(object sender, EventArgs e)
    {
      if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)
      {
        lbFolder.Text = folderBrowserDialog1.SelectedPath;
        folderSelected = true;
        saveFileDialog1.InitialDirectory = folderBrowserDialog1.SelectedPath;
        if (fileSelected) btConvert.Enabled = true;
      }
    }

    private void btFile_Click(object sender, EventArgs e)
    {
      if (saveFileDialog1.ShowDialog() == DialogResult.OK)
      {
        lbFile.Text = saveFileDialog1.FileName;
        fileSelected = true;
        if (folderSelected) btConvert.Enabled = true;
      }
    }

    private void btConvert_Click(object sender, EventArgs e)
    {
      var headers = new List<string>(new string[] { "DTSTART", "DTEND", "AALARM", "X-EPOCAGENDAENTRYTYPE", "X-BIRTHYEAR", "SUMMARY;ENCODING=QUOTED-PRINTABLE;CHARSET=UTF-8", "RRULE" });
      var list = new Dictionary<string, string>();
      string[] line;
      string t;
      var lineout = new List<string>();
      string prevQPKey = "";

      try
      {
        using (StreamWriter dest = new StreamWriter(saveFileDialog1.FileName,false, Encoding.UTF8))
        {
          fdLog.AppendText(string.Format("создан файл: {0}\n",saveFileDialog1.FileName));
          foreach (string p in headers) { lineout.Add(p); }
          dest.WriteLine(string.Join(",",lineout.ToArray()));

          try
          {
            DirectoryInfo folder = new DirectoryInfo(folderBrowserDialog1.SelectedPath);
            foreach (FileInfo file in folder.GetFiles("*.vcs"))
            {
              try
              {
                using (StreamReader source = new StreamReader(file.FullName))
                {
                  list.Clear();
                  lineout.Clear();
                  while (!source.EndOfStream)
                  {
                    line = source.ReadLine().Split(new Char[] {':'});
                    if (line.Length == 2)
                    {
                      if (line[0].Contains("QUOTED-PRINTABLE"))
                      {
                        line[1] = DecodeQuotedPrintable(line[1].TrimEnd('='), "utf-8");
                        prevQPKey = line[0];
                      }
                      else prevQPKey = "";
                      list[line[0]] = line[1];
                    }
                    else if (line.Length == 1 && line[0].Substring(0, 1) == "=" && prevQPKey != "")
                    {
                      list[prevQPKey] += DecodeQuotedPrintable(line[0].TrimEnd('='), "utf-8");
                    }
                  }
                }
                foreach (string p in headers)
                {
                  if (list.TryGetValue(p, out t)) lineout.Add(t);
                }
                dest.WriteLine(string.Join(",", lineout.ToArray()));
                fdLog.AppendText(string.Format("обработан файл: {0}\n", file.Name));
              }
              catch (Exception ex)
              {
                fdLog.AppendText(string.Format("ошибка при чтении файла: {0}\n", ex.Message));
              }
            }

          }
          catch (Exception ex)
          {
            fdLog.AppendText(string.Format("ошибка при работе с папкой: {0}\n", ex.Message));
          }

          fdLog.AppendText("операция завершена\n");
        }
      }
      catch (Exception ex)
      {
        fdLog.AppendText(string.Format("ошибка при записи файла: {0}\n", ex.Message));
      }
    }

    // http://stackoverflow.com/questions/11793734/code-for-encode-decode-quotedprintable
    // коверторы QPRINTABLE
    public static string DecodeQuotedPrintable(string input, string charSet)
    {
      Encoding enc;

      try
      {
        enc = Encoding.GetEncoding(charSet);
      }
      catch
      {
        enc = new UTF8Encoding();
      }

      var occurences = new Regex(@"(=[0-9A-Z]{2}){1,}", RegexOptions.Multiline);
      var matches = occurences.Matches(input);

      foreach (Match match in matches)
      {
        try
        {
          byte[] b = new byte[match.Groups[0].Value.Length / 3];
          for (int i = 0; i < match.Groups[0].Value.Length / 3; i++)
          {
            b[i] = byte.Parse(match.Groups[0].Value.Substring(i * 3 + 1, 2), System.Globalization.NumberStyles.AllowHexSpecifier);
          }
          char[] hexChar = enc.GetChars(b);
          input = input.Replace(match.Groups[0].Value, new String(hexChar));
        }
        catch
        { ;}
      }
      input = input.Replace("?=", "").Replace("\r\n", "");

      return input;
    }
  }
}