using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.IO;

namespace POP_Client
{
    class POP_Client
    {
        private TcpClient m_TcpClient;
        private NetworkStream m_NetStream;
        private StreamReader m_Reader;
        private string log;
        private string msg;

        public void Connect(string host, string login, string password)
        {
            // POP3 у нас на 110 порту
            m_TcpClient = new TcpClient(host, 110);
                // инициализация
                m_NetStream = m_TcpClient.GetStream(); // сетевой поток
                m_Reader = new StreamReader(m_TcpClient.GetStream()); // ассоциируем с ним ридер потока
                //Теперь POP3-сервер ожидает авторизацию
            //Выполняем авторизацию
            string result;
            //result = SendCmd(string.Format("PASS {0}", password));            
            result = SendCmd(string.Format("USER {0}", login));
            result = SendCmd(string.Format("PASS {0}", password));
            return;
        }

        private string SendCmd(string cmd)
        {
            string result = "";
            string m_Data = cmd + System.Environment.NewLine;
            byte[] szData;
            try
            {
                szData = System.Text.Encoding.ASCII.GetBytes(m_Data.ToCharArray()); //Преобразуем в строку ASCII
                m_NetStream.Write(szData, 0, szData.Length);
                result = m_Reader.ReadLine();
                log = "Result: " + result + "\r\n" + "Command: " + cmd + "\r\n" + log;
            }
            catch { }
            return result;
        }

        public int CheckMessages()
        {
            int count = 0,p;            
            string result;
            result = SendCmd("STAT";
            result = SendCmd("LIST";
            p = result.IndexOf(" ", 4);            
            count=int.Parse(result.Substring(4,p-3));
            if(count==0)
                result = SendCmd("QUIT";
            return count;
        }

        public string RetrieveSubject(int index)
        {
            string result, str;
            bool flag = false;
            result = SendCmd("RETR "+index);
            result = SendCmd("ELE " + index);
            result = SendCmd("QUIT";
            msg = "";
            str = m_Reader.ReadLine();
            while (str!=null)
            {
                if (str.Length > 7)
                    if (str.Substring(0, 8).ToLower() == "subject:"
                    {
                        result = str;
                    }
                if (str=="Content-Transfer-Encoding: base64"
                    flag = true;
                str = m_Reader.ReadLine();
                if (flag && str!="" && str!="\r\n"
                    msg += str+"\r\n";
            }
            result = result.Substring(8);
            result = result.TrimStart(" ".ToCharArray());
            return result;
        }

        public string GetMsg()
        {
            int p;
            string m = msg;
            msg = "";
            p = m.IndexOf("=\r\n";
            if (p == -1)
            {
                p = m.IndexOf("==\r\n";
                p++;
            }
            if (p <=0)
            {
                p = m.IndexOf("+\r\n";
            }
            m = m.Substring(0, p + 1);
            m = Encoding.UTF8.GetString(Convert.FromBase64String(m));
            return m;
        }

        public string GetLog()
        {
            string l=log;
            log="";
            return l;
        }

    }
}