using Helper;
using System;
using System.Collections.Generic;
using System.IO;
using System.Net.Sockets;
using System.Text;

namespace Helper
{
    /// <summary>
    /// Stellt eine E-Mail dar.
    /// </summary>
    public class Mail
    {
        #region Vars
        private string mSenderMail;
        private string mReceiverMail;
        private string mTitle;
        private string mContent;
        private string mDate;
        #endregion

        #region Properties
        /// <summary>
        /// E-Mail Adresse des Versenders
        /// </summary>
        public string SenderMail
        {
            get { return mSenderMail; }
            set { mSenderMail = value; }
        }
        /// <summary>
        /// E-Mail Adresse des Empfängers
        /// </summary>
        public string ReceiverMail
        {
            get { return mReceiverMail; }
            set { mReceiverMail = value; }
        }
        /// <summary>
        /// Betreff
        /// </summary>
        public string Title
        {
            get { return mTitle; }
            set { mTitle = value; }
        }
        /// <summary>
        /// Inhalt
        /// </summary>
        public string Content
        {
            get { return mContent; }
            set { mContent = value; }
        }
        /// <summary>
        /// Datum und Zeit
        /// </summary>
        public string Date
        {
            get { return mDate; }
            set { mDate = value; }
        }
        #endregion
    }
}

    /// <summary>
    /// Stellt einen MailProvider zur Verfügung,
    /// der E-Mails abrufen kann.
    /// </summary>
    public class MailProvider
    {
        #region Vars
        private NetworkStream mPop3Stream;
        private StreamReader mStreamListener;
        private byte[] mCommandBuffer = new byte[1024];
        ASCIIEncoding mAscEncoding = new ASCIIEncoding();
        private string mPopServer;
        private int mPort;
        private string mUser;
        private string mPassword;
        #endregion

        #region Properties
        /// <summary>
        /// POP-3 Server
        /// </summary>
        public string PopServer
        {
            get { return mPopServer; }
            set { mPopServer = value; }
        }
        /// <summary>
        /// Port des Servers
        /// </summary>
        public int Port
        {
            get { return mPort; }
            set { mPort = value; }
        }
        /// <summary>
        /// Benutzername
        /// </summary>
        public string User
        {
            get { return mUser; }
            set { mUser = value; }
        }
        /// <summary>
        /// Passwort
        /// </summary>
        public string Password
        {
            set { mPassword = value; }
        }
        #endregion

        #region Ctor
        /// <summary>
        /// Initialisiert einen neuen MailProvider,
        /// der E-Mail empfangen kann.
        /// </summary>
        public MailProvider(string popServer, int port, string user, string pw)
        {
            // Zugangsinformationen zuweisen
            mPopServer = popServer;
            mPort = port;
            mUser = user;
            mPassword = pw;

            // Verbindung zum Server herstellen
            establishConnection();
        }
        #endregion

        #region Private Methods
        /// <summary>
        /// Stellt die Verbindung zum POP-Server her.
        /// </summary>
        private void establishConnection()
        {
            TcpClient server = new TcpClient();

            // Verbindung herstellen
            server.Connect(this.PopServer, this.Port);

            // Streams einleiten
            mPop3Stream = server.GetStream();
            mStreamListener = new StreamReader(mPop3Stream);

            // Wenn erfolgreich verbunden
            if (server.Connected)
            {
                mStreamListener.ReadLine();

                // Am Server anmelden
                mCommandBuffer = mAscEncoding.GetBytes(String.Format("USER {0}\r\n", this.User));
                mPop3Stream.Write(mCommandBuffer, 0, mCommandBuffer.Length);
                mStreamListener.ReadLine();
                mCommandBuffer = mAscEncoding.GetBytes(String.Format("PASS {0}\r\n", mPassword));
                mPop3Stream.Write(mCommandBuffer, 0, mCommandBuffer.Length);
                mStreamListener.ReadLine();
            }
        }
        /// <summary>
        /// Parst anhand des übergebenen Strings ein Mail-Objekt.
        /// </summary>
        private Mail parseMail(string input)
        {
            Mail retVal = null;

            // E-Mail in 2 Hälften zerlegen (Header und Body)
            string[] emailSplit = input.Split(new string[] { "\r\n\r\n" }, StringSplitOptions.None);
            string header = String.Empty;
            string body = String.Empty;

            if (emailSplit.Length >= 2)
            {
                // Header
                header = emailSplit[0];
                // Body
                for (int i = 1; i < emailSplit.Length - 1; i++) body = String.Concat(body, "\r\n\r\n", emailSplit[i]);
            }

            // Header-Informationen filtern
            retVal = getHeaderInformations(header);

            // Content zuweisen
            retVal.Content = body;

            // Mail-Objekt zurückgeben
            return retVal;
        }
        /// <summary>
        /// Gibt die Headerinformationen zurück.
        /// </summary>
        private Mail getHeaderInformations(string header)
        {
            Mail retVal = new Mail();

            // Jede einzelne Zeile parsen
            foreach (string line in header.Split(new string[] { "\r\n" }, StringSplitOptions.None))
            {
                // Aufteilen in Schlüssel und Wert
                string[] lineSplit = line.Split(new string[] { ": " }, StringSplitOptions.None);
                string key = String.Empty;
                string value = String.Empty;

                if (lineSplit.Length >= 2)
                {
                    // Schlüssel
                    key = lineSplit[0];
                    // Wert
                    for (int i = 1; i < lineSplit.Length; i++) value = String.Concat(value, lineSplit[i]);
                }

                // Je nach Schlüssel den dazugehörigen Wert zuweisen
                switch (key)
                {
                    // Absender
                    case "From":
                        retVal.SenderMail = value;
                        break;
                    // Empfänger
                    case "To":
                        retVal.ReceiverMail = value;
                        break;
                    // Betreff
                    case "Subject":
                        retVal.Title = value;
                        break;
                    //Datum und Zeit
                    case "Date":
                        retVal.Date = value;
                        break;
            }
            }

            return retVal;
        }
        #endregion

        #region Public Methods
        /// <summary>
        /// Gibt alle E-Mails zurück.
        /// </summary>
        public List<Mail> GetMails(bool deleteMails)
        {
            List<Mail> retVal = new List<Mail>();
            List<string> mailList = new List<string>();

            // Liste mit allen E-Mails anfordern
            mCommandBuffer = mAscEncoding.GetBytes("LIST\r\n");
            mPop3Stream.Write(mCommandBuffer, 0, mCommandBuffer.Length);
            mStreamListener.ReadLine();

            // Solange wie nicht "." ausgelesen wird, sind noch E-Mails
            // auf dem Server vorhanden
            string currMsg = mStreamListener.ReadLine();
            while (currMsg != ".")
            {
                mailList.Add(currMsg);
                currMsg = mStreamListener.ReadLine();
            }

            // Die E-Mail Liste durchgehen
            foreach (string listVal in mailList)
            {
                Mail mail = null;

                // Mail-Index filtern
                int mailNr = -1;
                try
                {
                    mailNr = Convert.ToInt32(listVal.Split(' ')[0]);
                }
                catch { }

                // Wenn der Mail-Index gefunden wurde, kompletten Mail Inhalt abrufen
                if (mailNr != -1)
                {
                    mCommandBuffer = mAscEncoding.GetBytes(String.Format("RETR {0}\r\n",
                        mailNr));
                    mPop3Stream.Write(mCommandBuffer, 0, mCommandBuffer.Length);
                    StringBuilder mailContent = new StringBuilder();

                    // Solange nicht "." augelesen wird, ist die Email noch nicht zuende
                    string tmpLine = mStreamListener.ReadLine();
                    while (tmpLine != ".")
                    {
                        mailContent.AppendLine(tmpLine);
                        tmpLine = mStreamListener.ReadLine();
                    }

                    // E-Mail parsen
                    mail = parseMail(mailContent.ToString());

                //Mail löschen
                if (deleteMails == true)
                {
                    mCommandBuffer = mAscEncoding.GetBytes(String.Format("DELE {0}\r\n", mailNr));
                    mPop3Stream.Write(mCommandBuffer, 0, mCommandBuffer.Length);
                    mStreamListener.ReadLine();
                }
            }

                if (mail != null)
                    retVal.Add(mail);
            }
        mCommandBuffer = mAscEncoding.GetBytes(String.Format("QUIT\r\n"));
        mPop3Stream.Write(mCommandBuffer, 0, mCommandBuffer.Length);
        mStreamListener.ReadLine();
        return retVal;
        }
        #endregion
}