using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Net.Mail;
using System.Net.Mime;
using System.Net.Security;
using System.Net.Sockets;
using System.Text;
using System.Text.RegularExpressions;

namespace Roblox.Common
{
    public class Email
    {
        private static string defaultSMTPServer = global::Roblox.Common.Properties.Settings.Default.SMTPServer;
        private const string linebreak = "\r\n";

        static Email()
        {
            EventLog.WriteEntry(
                LogInstaller.SourceName,
                String.Format("Roblox.Common.Email.SMTPServer is {0}", defaultSMTPServer),
                EventLogEntryType.Information
            );
        }

        public static void SendEmail(string to, string from, string subject, string body)
        {
            SendEmail(to, from, subject, body, defaultSMTPServer);
        }
        public static void SendEmail(string to, string from, string subject, string body, string smtpServer)
        {
            if (to.Trim().Length == 0)
                return;

            var smtpClient = new SmtpClient(smtpServer);
            using (var message = new MailMessage(from, to, subject, body))
            {
                smtpClient.Send(message);
            }
        }
        public static void SendMimeEmail(string to, string from, string subject, string plaintextbody, string htmlbody)
        {
            ContentType mimeType = new System.Net.Mime.ContentType("text/html");
            AlternateView alternate = AlternateView.CreateAlternateViewFromString(htmlbody, mimeType);

            SmtpClient client = new SmtpClient(defaultSMTPServer);
            client.Credentials = CredentialCache.DefaultNetworkCredentials;

            using (var message = new MailMessage(from, to, subject, plaintextbody))
            {
                message.AlternateViews.Add(alternate);
                client.Send(message);
            }
        }
        public static void SendMimeEmail(string to, string from, string subject, string plaintextbody, string htmlbody, string smtpServer)
        {
            if (to.Trim().Length == 0)
                return;

            ContentType mimeType = new System.Net.Mime.ContentType("text/html");
            AlternateView alternate = AlternateView.CreateAlternateViewFromString(htmlbody, mimeType);

            SmtpClient client = new SmtpClient(smtpServer);
            client.Credentials = CredentialCache.DefaultNetworkCredentials;

            using (var message = new MailMessage(from, to, subject, plaintextbody))
            {
                message.AlternateViews.Add(alternate);
                client.Send(message);
            }
        }
        public static MailMessageEx ParseEmail(string rawEmail)
        {
            Mime.MimeReader reader = new Roblox.Common.Mime.MimeReader(Regex.Split(rawEmail, linebreak));
            Mime.MimeEntity mime = reader.CreateMimeEntity();
            return mime.ToMailMessageEx();
        }
    }

    // POP3 Client
    // ===========
    //
    // copyright by Peter Huber, Singapore, 2006
    // this code is provided as is, bugs are probable, free for any use, no responsibility accepded :-)
    //
    // based on POP3 Client as a C# Class, by Bull Dean, http://www.codeproject.com/csharp/Pop3MailClient.asp
    // based on Retrieve Mail From a POP3 Server using C#, by Agus Kurniawan, http://www.codeproject.com/csharp/popapp.asp
    // based on Post Office Protocol - Version 3, http://www.ietf.org/rfc/rfc1939.txt

    namespace Mail.Pop3
    {
        // Supporting classes and structs
        // ==============================

        /// <summary>
        /// Combines Email ID with Email UID for one email
        /// The POP3 server assigns to each message a unique Email UID, which will not change for the life time
        /// of the message and no other message should use the same.
        /// 
        /// Exceptions:
        /// Throws Pop3Exception if there is a serious communication problem with the POP3 server, otherwise
        /// 
        /// </summary>
        public struct EmailUid
        {
            /// <summary>
            /// used in POP3 commands to indicate which message (only valid in the present session)
            /// </summary>
            public int EmailId;
            /// <summary>
            /// Uid is always the same for a message, regardless of session
            /// </summary>
            public string Uid;

            /// <summary>
            /// 
            /// </summary>
            /// <param name="EmailId"></param>
            /// <param name="Uid"></param>
            public EmailUid(int EmailId, string Uid)
            {
                this.EmailId = EmailId;
                this.Uid = Uid;
            }
        }


        /// <summary>
        /// If anything goes wrong within Pop3MailClient, a Pop3Exception is raised
        /// </summary>
        public class Pop3Exception : ApplicationException
        {
            /// <summary>
            /// 
            /// </summary>
            public Pop3Exception() { }
            /// <summary>
            /// 
            /// </summary>
            /// <param name="ErrorMessage"></param>
            public Pop3Exception(string ErrorMessage) : base(ErrorMessage) { }
        }


        /// <summary>
        /// A pop 3 connection goes through the following states:
        /// </summary>
        public enum Pop3ConnectionStateEnum
        {
            /// <summary>
            /// undefined
            /// </summary>
            None = 0,
            /// <summary>
            /// not connected yet to POP3 server
            /// </summary>
            Disconnected,
            /// <summary>
            /// TCP connection has been opened and the POP3 server has sent the greeting. POP3 server expects user name and password
            /// </summary>
            Authorization,
            /// <summary>
            /// client has identified itself successfully with the POP3, server has locked all messages 
            /// </summary>
            Connected,
            /// <summary>
            /// QUIT command was sent, the server has deleted messages marked for deletion and released the resources
            /// </summary>
            Closed
        }


        // Delegates for Pop3MailClient
        // ============================

        /// <summary>
        /// If POP3 Server doesn't react as expected or this code has a problem, but
        /// can continue with the execution, a Warning is called.
        /// </summary>
        /// <param name="WarningText"></param>
        /// <param name="Response">string received from POP3 server</param>
        public delegate void WarningHandler(string WarningText, string Response);


        /// <summary>
        /// Traces all the information exchanged between POP3 client and POP3 server plus some
        /// status messages from POP3 client.
        /// Helpful to investigate any problem.
        /// Console.WriteLine() can be used
        /// </summary>
        /// <param name="TraceText"></param>
        public delegate void TraceHandler(string TraceText);


        // Pop3MailClient Class
        // ====================  

        /// <summary>
        /// provides access to emails on a POP3 Server
        /// </summary>
        public class Pop3MailClient : IDisposable
        {

            //Events
            //------

            /// <summary>
            /// Called whenever POP3 server doesn't react as expected, but no runtime error is thrown.
            /// </summary>
            public event WarningHandler Warning;

            /// <summary>
            /// call warning event
            /// </summary>
            /// <param name="methodName">name of the method where warning is needed</param>
            /// <param name="response">answer from POP3 server causing the warning</param>
            /// <param name="warningText">explanation what went wrong</param>
            /// <param name="warningParameters"></param>
            protected void CallWarning(string methodName, string response, string warningText, params object[] warningParameters)
            {
                warningText = string.Format(warningText, warningParameters);
                if (Warning != null)
                {
                    Warning(methodName + ": " + warningText, response);
                }
                CallTrace("!! {0}", warningText);
            }


            /// <summary>
            /// Shows the communication between PopClient and PopServer, including warnings
            /// </summary>
            public event TraceHandler Trace;

            /// <summary>
            /// call Trace event
            /// </summary>
            /// <param name="text">string to be traced</param>
            /// <param name="parameters"></param>
            protected void CallTrace(string text, params object[] parameters)
            {
                if (Trace != null)
                {
                    Trace(DateTime.Now.ToString("hh:mm:ss ") + popServer + " " + string.Format(text, parameters));
                }
            }

            /// <summary>
            /// Trace information received from POP3 server
            /// </summary>
            /// <param name="text">string to be traced</param>
            /// <param name="parameters"></param>
            protected void TraceFrom(string text, params object[] parameters)
            {
                if (Trace != null)
                {
                    CallTrace("   " + string.Format(text, parameters));
                }
            }


            //Properties
            //----------

            /// <summary>
            /// Get POP3 server name
            /// </summary>
            public string PopServer
            {
                get { return popServer; }
            }
            /// <summary>
            /// POP3 server name
            /// </summary>
            protected string popServer;


            /// <summary>
            /// Get POP3 server port
            /// </summary>
            public int Port
            {
                get { return port; }
            }
            /// <summary>
            /// POP3 server port
            /// </summary>
            protected int port;


            /// <summary>
            /// Should SSL be used for connection with POP3 server ?
            /// </summary>
            public bool UseSSL
            {
                get { return useSSL; }
            }
            /// <summary>
            /// Should SSL be used for connection with POP3 server ?
            /// </summary>
            private bool useSSL;


            /// <summary>
            /// should Pop3MailClient automatically reconnect if POP3 server has dropped the 
            /// connection due to a timeout ?
            /// </summary>
            public bool IsAutoReconnect
            {
                get { return isAutoReconnect; }
                set { isAutoReconnect = value; }
            }
            private bool isAutoReconnect = false;
            //timeout has occured, we try to perform an autoreconnect
            private bool isTimeoutReconnect = false;



            /// <summary>
            /// Get / set read timeout (miliseconds)
            /// </summary>
            public int ReadTimeout
            {
                get { return readTimeout; }
                set
                {
                    readTimeout = value;
                    if (pop3Stream != null && pop3Stream.CanTimeout)
                    {
                        pop3Stream.ReadTimeout = readTimeout;
                    }
                }
            }
            /// <summary>
            /// POP3 server read timeout
            /// </summary>
            protected int readTimeout = -1;


            /// <summary>
            /// Get owner name of mailbox on POP3 server
            /// </summary>
            public string Username
            {
                get { return username; }
            }
            /// <summary>
            /// Owner name of mailbox on POP3 server
            /// </summary>
            protected string username;


            /// <summary>
            /// Get password for mailbox on POP3 server
            /// </summary>
            public string Password
            {
                get { return password; }
            }
            /// <summary>
            /// Password for mailbox on POP3 server
            /// </summary>
            protected string password;


            /// <summary>
            /// Get connection status with POP3 server
            /// </summary>
            public Pop3ConnectionStateEnum Pop3ConnectionState
            {
                get { return pop3ConnectionState; }
            }
            /// <summary>
            /// connection status with POP3 server
            /// </summary>
            protected Pop3ConnectionStateEnum pop3ConnectionState = Pop3ConnectionStateEnum.Disconnected;


            // Methods
            // -------

            /// <summary>
            /// set POP3 connection state
            /// </summary>
            /// <param name="State"></param>
            protected void setPop3ConnectionState(Pop3ConnectionStateEnum State)
            {
                pop3ConnectionState = State;
                CallTrace("   Pop3MailClient Connection State {0} reached", State);
            }

            /// <summary>
            /// throw exception if POP3 connection is not in the required state
            /// </summary>
            /// <param name="requiredState"></param>
            protected void EnsureState(Pop3ConnectionStateEnum requiredState)
            {
                if (pop3ConnectionState != requiredState)
                {
                    // wrong connection state
                    throw new Pop3Exception("GetMailboxStats only accepted during connection state: " + requiredState.ToString() +
                          "\n The connection to server " + popServer + " is in state " + pop3ConnectionState.ToString());
                }
            }


            //private fields
            //--------------
            /// <summary>
            /// TCP to POP3 server
            /// </summary>
            private TcpClient serverTcpConnection;
            /// <summary>
            /// Stream from POP3 server with or without SSL
            /// </summary>
            private Stream pop3Stream;
            /// <summary>
            /// Reader for POP3 message
            /// </summary>
            protected StreamReader pop3StreamReader;
            /// <summary>
            /// char 'array' for carriage return / line feed
            /// </summary>
            protected string CRLF = "\r\n";


            //public methods
            //--------------

            /// <summary>
            /// Make POP3 client ready to connect to POP3 server
            /// </summary>
            /// <param name="PopServer"><example>pop.gmail.com</example></param>
            /// <param name="Port"><example>995</example></param>
            /// <param name="useSSL">True: SSL is used for connection to POP3 server</param>
            /// <param name="Username"><example>abc@gmail.com</example></param>
            /// <param name="Password">Secret</param>
            public Pop3MailClient(string PopServer, int Port, bool useSSL, string Username, string Password)
            {
                this.popServer = PopServer;
                this.port = Port;
                this.useSSL = useSSL;
                this.username = Username;
                this.password = Password;
            }


            /// <summary>
            /// Connect to POP3 server
            /// </summary>
            public void Connect()
            {
                if (pop3ConnectionState != Pop3ConnectionStateEnum.Disconnected &&
                  pop3ConnectionState != Pop3ConnectionStateEnum.Closed &&
                  !isTimeoutReconnect)
                {
                    CallWarning("connect", "", "Connect command received, but connection state is: " + pop3ConnectionState.ToString());
                }
                else
                {
                    //establish TCP connection
                    try
                    {
                        CallTrace("   Connect at port {0}", port);
                        serverTcpConnection = new TcpClient(popServer, port);
                    }
                    catch (Exception ex)
                    {
                        throw new Pop3Exception("Connection to server " + popServer + ", port " + port + " failed.\nRuntime Error: " + ex.ToString());
                    }

                    if (useSSL)
                    {
                        //get SSL stream
                        try
                        {
                            CallTrace("   Get SSL connection");
                            pop3Stream = new SslStream(serverTcpConnection.GetStream(), false);
                            pop3Stream.ReadTimeout = readTimeout;
                        }
                        catch (Exception ex)
                        {
                            throw new Pop3Exception("Server " + popServer + " found, but cannot get SSL data stream.\nRuntime Error: " + ex.ToString());
                        }

                        //perform SSL authentication
                        try
                        {
                            CallTrace("   Get SSL authentication");
                            ((SslStream)pop3Stream).AuthenticateAsClient(popServer);
                        }
                        catch (Exception ex)
                        {
                            throw new Pop3Exception("Server " + popServer + " found, but problem with SSL Authentication.\nRuntime Error: " + ex.ToString());
                        }
                    }
                    else
                    {
                        //create a stream to POP3 server without using SSL
                        try
                        {
                            CallTrace("   Get connection without SSL");
                            pop3Stream = serverTcpConnection.GetStream();
                            pop3Stream.ReadTimeout = readTimeout;
                        }
                        catch (Exception ex)
                        {
                            throw new Pop3Exception("Server " + popServer + " found, but cannot get data stream (without SSL).\nRuntime Error: " + ex.ToString());
                        }
                    }
                    //get stream for reading from pop server
                    //POP3 allows only US-ASCII. The message will be translated in the proper encoding in a later step
                    try
                    {
                        pop3StreamReader = new StreamReader(pop3Stream, Encoding.ASCII);
                    }
                    catch (Exception ex)
                    {
                        if (useSSL)
                        {
                            throw new Pop3Exception("Server " + popServer + " found, but cannot read from SSL stream.\nRuntime Error: " + ex.ToString());
                        }
                        else
                        {
                            throw new Pop3Exception("Server " + popServer + " found, but cannot read from stream (without SSL).\nRuntime Error: " + ex.ToString());
                        }
                    }

                    //ready for authorisation
                    string response;
                    if (!readSingleLine(out response))
                    {
                        throw new Pop3Exception("Server " + popServer + " not ready to start AUTHORIZATION.\nMessage: " + response);
                    }
                    setPop3ConnectionState(Pop3ConnectionStateEnum.Authorization);

                    //send user name
                    if (!executeCommand("USER " + username, out response))
                    {
                        throw new Pop3Exception("Server " + popServer + " doesn't accept username '" + username + "'.\nMessage: " + response);
                    }

                    //send password
                    if (!executeCommand("PASS " + password, out response))
                    {
                        throw new Pop3Exception("Server " + popServer + " doesn't accept password '" + password + "' for user '" + username + "'.\nMessage: " + response);
                    }

                    setPop3ConnectionState(Pop3ConnectionStateEnum.Connected);
                }
            }


            /// <summary>
            /// Disconnect from POP3 Server
            /// </summary>
            public void Disconnect()
            {
                if (pop3ConnectionState == Pop3ConnectionStateEnum.Disconnected ||
                  pop3ConnectionState == Pop3ConnectionStateEnum.Closed)
                {
                    CallWarning("disconnect", "", "Disconnect received, but was already disconnected.");
                }
                else
                {
                    //ask server to end session and possibly to remove emails marked for deletion
                    try
                    {
                        string response;
                        if (executeCommand("QUIT", out response))
                        {
                            //server says everything is ok
                            setPop3ConnectionState(Pop3ConnectionStateEnum.Closed);
                        }
                        else
                        {
                            //server says there is a problem
                            CallWarning("Disconnect", response, "negative response from server while closing connection: " + response);
                            setPop3ConnectionState(Pop3ConnectionStateEnum.Disconnected);
                        }
                    }
                    finally
                    {
                        //close connection
                        if (pop3Stream != null)
                        {
                            pop3Stream.Close();
                        }

                        pop3StreamReader.Close();
                    }
                }
            }


            /// <summary>
            /// Delete message from server.
            /// The POP3 server marks the message as deleted.  Any future
            /// reference to the message-number associated with the message
            /// in a POP3 command generates an error.  The POP3 server does
            /// not actually delete the message until the POP3 session
            /// enters the UPDATE state.
            /// </summary>
            /// <param name="msg_number"></param>
            /// <returns></returns>
            public bool DeleteEmail(int msg_number)
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                string response;
                if (!executeCommand("DELE " + msg_number.ToString(), out response))
                {
                    CallWarning("DeleteEmail", response, "negative response for email (Id: {0}) delete request", msg_number);
                    return false;
                }
                return true;
            }


            /// <summary>
            /// Get a list of all Email IDs available in mailbox
            /// </summary>
            /// <returns></returns>
            public bool GetEmailIdList(out List<int> EmailIds)
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                EmailIds = new List<int>();

                //get server response status line
                string response;
                if (!executeCommand("LIST", out response))
                {
                    CallWarning("GetEmailIdList", response, "negative response for email list request");
                    return false;
                }

                //get every email id
                int EmailId;
                while (readMultiLine(out response))
                {
                    if (int.TryParse(response.Split(' ')[0], out EmailId))
                    {
                        EmailIds.Add(EmailId);
                    }
                    else
                    {
                        CallWarning("GetEmailIdList", response, "first characters should be integer (EmailId)");
                    }
                }
                TraceFrom("{0} email ids received", EmailIds.Count);
                return true;
            }


            /// <summary>
            /// get size of one particular email
            /// </summary>
            /// <param name="msg_number"></param>
            /// <returns></returns>
            public int GetEmailSize(int msg_number)
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                string response;
                executeCommand("LIST " + msg_number.ToString(), out response);
                int EmailSize = 0;
                string[] responseSplit = response.Split(' ');
                if (responseSplit.Length < 2 || !int.TryParse(responseSplit[2], out EmailSize))
                {
                    CallWarning("GetEmailSize", response, "'+OK int int' format expected (EmailId, EmailSize)");
                }

                return EmailSize;
            }


            /// <summary>
            /// Get a list with the unique IDs of all Email available in mailbox.
            /// 
            /// Explanation:
            /// EmailIds for the same email can change between sessions, whereas the unique Email id
            /// never changes for an email.
            /// </summary>
            /// <param name="EmailIds"></param>
            /// <returns></returns>
            public bool GetUniqueEmailIdList(out List<EmailUid> EmailIds)
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                EmailIds = new List<EmailUid>();

                //get server response status line
                string response;
                if (!executeCommand("UIDL ", out response))
                {
                    CallWarning("GetUniqueEmailIdList", response, "negative response for email list request");
                    return false;
                }

                //get every email unique id
                int EmailId;
                while (readMultiLine(out response))
                {
                    string[] responseSplit = response.Split(' ');
                    if (responseSplit.Length < 2)
                    {
                        CallWarning("GetUniqueEmailIdList", response, "response not in format 'int string'");
                    }
                    else if (!int.TryParse(responseSplit[0], out EmailId))
                    {
                        CallWarning("GetUniqueEmailIdList", response, "first charaters should be integer (Unique EmailId)");
                    }
                    else
                    {
                        EmailIds.Add(new EmailUid(EmailId, responseSplit[1]));
                    }
                }
                TraceFrom("{0} unique email ids received", EmailIds.Count);
                return true;
            }


            /// <summary>
            /// get a list with all currently available messages and the UIDs
            /// </summary>
            /// <param name="EmailIds">EmailId Uid list</param>
            /// <returns>false: server sent negative response (didn't send list)</returns>
            public bool GetUniqueEmailIdList(out SortedList<string, int> EmailIds)
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                EmailIds = new SortedList<string, int>();

                //get server response status line
                string response;
                if (!executeCommand("UIDL", out response))
                {
                    CallWarning("GetUniqueEmailIdList", response, "negative response for email list request");
                    return false;
                }

                //get every email unique id
                int EmailId;
                while (readMultiLine(out response))
                {
                    string[] responseSplit = response.Split(' ');
                    if (responseSplit.Length < 2)
                    {
                        CallWarning("GetUniqueEmailIdList", response, "response not in format 'int string'");
                    }
                    else if (!int.TryParse(responseSplit[0], out EmailId))
                    {
                        CallWarning("GetUniqueEmailIdList", response, "first charaters should be integer (Unique EmailId)");
                    }
                    else
                    {
                        EmailIds.Add(responseSplit[1], EmailId);
                    }
                }
                TraceFrom("{0} unique email ids received", EmailIds.Count);
                return true;
            }


            /// <summary>
            /// get size of one particular email
            /// </summary>
            /// <param name="msg_number"></param>
            /// <returns></returns>
            public int GetUniqueEmailId(EmailUid msg_number)
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                string response;
                executeCommand("LIST " + msg_number.ToString(), out response);
                int EmailSize = 0;
                string[] responseSplit = response.Split(' ');
                if (responseSplit.Length < 2 || !int.TryParse(responseSplit[2], out EmailSize))
                {
                    CallWarning("GetEmailSize", response, "'+OK int int' format expected (EmailId, EmailSize)");
                }

                return EmailSize;
            }


            /// <summary>
            /// Sends an 'empty' command to the POP3 server. Server has to respond with +OK
            /// </summary>
            /// <returns>true: server responds as expected</returns>
            public bool NOOP()
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                string response;
                if (!executeCommand("NOOP", out response))
                {
                    CallWarning("NOOP", response, "negative response for NOOP request");
                    return false;
                }
                return true;
            }

            /// <summary>
            /// Should the raw content, the US-ASCII code as received, be traced
            /// GetRawEmail will switch it on when it starts and off once finished
            /// 
            /// Inheritors might use it to get the raw email
            /// </summary>
            protected bool isTraceRawEmail = false;


            /// <summary>
            /// contains one MIME part of the email in US-ASCII, needs to be translated in .NET string (Unicode)
            /// contains the complete email in US-ASCII, needs to be translated in .NET string (Unicode)
            /// For speed reasons, reuse StringBuilder
            /// </summary>
            protected StringBuilder RawEmailSB;


            /// <summary>
            /// Reads the complete text of a message
            /// </summary>
            /// <param name="MessageNo">Email to retrieve</param>
            /// <param name="EmailText">ASCII string of complete message</param>
            /// <returns></returns>
            public bool GetRawEmail(int MessageNo, out string EmailText)
            {
                //send 'RETR int' command to server
                if (!SendRetrCommand(MessageNo))
                {
                    EmailText = null;
                    return false;
                }

                //get the lines
                string response;
                int LineCounter = 0;
                //empty StringBuilder
                if (RawEmailSB == null)
                {
                    RawEmailSB = new StringBuilder(100000);
                }
                else
                {
                    RawEmailSB.Length = 0;
                }
                isTraceRawEmail = true;
                while (readMultiLine(out response))
                {
                    LineCounter += 1;
                }
                EmailText = RawEmailSB.ToString();
                TraceFrom("email with {0} lines,  {1} chars received", LineCounter.ToString(), EmailText.Length);
                return true;
            }


            ///// <summary>
            ///// Requests from POP3 server a specific email and returns a stream with the message content (header and body)
            ///// </summary>
            ///// <param name="MessageNo"></param>
            ///// <param name="EmailStreamReader"></param>
            ///// <returns>false: POP3 server cannot provide this message</returns>
            //public bool GetEmailStream(int MessageNo, out StreamReader EmailStreamReader) {
            //  //send 'RETR int' command to server
            //  if (!SendRetrCommand(MessageNo)) {
            //    EmailStreamReader = null;
            //    return false;
            //  }
            //  EmailStreamReader = sslStreamReader;
            //  return true;
            //}


            /// <summary>
            /// Unmark any emails from deletion. The server only deletes email really
            /// once the connection is properly closed.
            /// </summary>
            /// <returns>true: emails are unmarked from deletion</returns>
            public bool UndeleteAllEmails()
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                string response;
                return executeCommand("RSET", out response);
            }


            /// <summary>
            /// Get mailbox statistics
            /// </summary>
            /// <param name="NumberOfMails"></param>
            /// <param name="MailboxSize"></param>
            /// <returns></returns>
            public bool GetMailboxStats(out int NumberOfMails, out int MailboxSize)
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);

                //interpret response
                string response;
                NumberOfMails = 0;
                MailboxSize = 0;
                if (executeCommand("STAT", out response))
                {
                    //got a positive response
                    string[] responseParts = response.Split(' ');
                    if (responseParts.Length < 2)
                    {
                        //response format wrong
                        throw new Pop3Exception("Server " + popServer + " sends illegally formatted response." +
                          "\nExpected format: +OK int int" +
                          "\nReceived response: " + response);
                    }
                    NumberOfMails = int.Parse(responseParts[1]);
                    MailboxSize = int.Parse(responseParts[2]);
                    return true;
                }
                return false;
            }


            /// <summary>
            /// Send RETR command to POP 3 server to fetch one particular message
            /// </summary>
            /// <param name="MessageNo">ID of message required</param>
            /// <returns>false: negative server respond, message not delivered</returns>
            protected bool SendRetrCommand(int MessageNo)
            {
                EnsureState(Pop3ConnectionStateEnum.Connected);
                // retrieve mail with message number
                string response;
                if (!executeCommand("RETR " + MessageNo.ToString(), out response))
                {
                    CallWarning("GetRawEmail", response, "negative response for email (ID: {0}) request", MessageNo);
                    return false;
                }
                return true;
            }


            //Helper methodes
            //---------------

            /// <summary>
            /// sends the 4 letter command to POP3 server (adds CRLF) and waits for the
            /// response of the server
            /// </summary>
            /// <param name="command">command to be sent to server</param>
            /// <param name="response">answer from server</param>
            /// <returns>false: server sent negative acknowledge, i.e. server could not execute command</returns>

            public bool isDebug = false;
            private bool executeCommand(string command, out string response)
            {
                //send command to server
                byte[] commandBytes = System.Text.Encoding.ASCII.GetBytes((command + CRLF).ToCharArray());
                CallTrace("Tx '{0}'", command);
                bool isSupressThrow = false;
                try
                {
                    pop3Stream.Write(commandBytes, 0, commandBytes.Length);
                    if (isDebug)
                    {
                        isDebug = false;
                        throw new IOException("Test", new SocketException(10053));
                    }
                }
                catch (IOException ex)
                {
                    //Unable to write data to the transport connection. Check if reconnection should be tried
                    isSupressThrow = executeReconnect(ex, command, commandBytes);
                    if (!isSupressThrow)
                    {
                        throw;
                    }
                }
                pop3Stream.Flush();

                //read response from server
                response = null;
                try
                {
                    response = pop3StreamReader.ReadLine();
                }
                catch (IOException ex)
                {
                    //Unable to write data to the transport connection. Check if reconnection should be tried
                    isSupressThrow = executeReconnect(ex, command, commandBytes);
                    if (isSupressThrow)
                    {
                        //wait for response one more time
                        response = pop3StreamReader.ReadLine();
                    }
                    else
                    {
                        throw;
                    }
                }
                if (response == null)
                {
                    throw new Pop3Exception("Server " + popServer + " has not responded, timeout has occured.");
                }
                CallTrace("Rx '{0}'", response);
                return (response.Length > 0 && response[0] == '+');
            }


            /// <summary>
            /// reconnect, if there is a timeout exception and isAutoReconnect is true
            /// 
            /// </summary>
            private bool executeReconnect(IOException ex, string command, byte[] commandBytes)
            {
                if (ex.InnerException != null && ex.InnerException is SocketException)
                {
                    //SocketException
                    SocketException innerEx = (SocketException)ex.InnerException;
                    if (innerEx.ErrorCode == 10053)
                    {
                        //probably timeout: An established connection was aborted by the software in your host machine.
                        CallWarning("ExecuteCommand", "", "probably timeout occured");
                        if (isAutoReconnect)
                        {
                            //try to reconnect and send one more time
                            isTimeoutReconnect = true;
                            try
                            {
                                CallTrace("   try to auto reconnect");
                                Connect();

                                CallTrace("   reconnect successful, try to resend command");
                                CallTrace("Tx '{0}'", command);
                                pop3Stream.Write(commandBytes, 0, commandBytes.Length);
                                pop3Stream.Flush();
                                return true;
                            }
                            finally
                            {
                                isTimeoutReconnect = false;
                            }

                        }
                    }
                }
                return false;
            }


            /*
                /// <summary>
                /// sends the 4 letter command to POP3 server (adds CRLF)
                /// </summary>
                /// <param name="command"></param>
                protected void SendCommand(string command) {
                  byte[] commandBytes = System.Text.Encoding.ASCII.GetBytes((command + CRLF).ToCharArray());
                  CallTrace("Tx '{0}'", command);
                  try {
                    pop3Stream.Write(commandBytes, 0, commandBytes.Length);
                  } catch (IOException ex) {
                    //Unable to write data to the transport connection:
                    if (ex.InnerException!=null && ex.InnerException is SocketException) {
                      //SocketException
                      SocketException innerEx = (SocketException)ex.InnerException;
                      if (innerEx.ErrorCode==10053) {
                        //probably timeout: An established connection was aborted by the software in your host machine.
                        CallWarning("SendCommand", "", "probably timeout occured");
                        if (isAutoReconnect) {
                          //try to reconnect and send one more time
                          isTimeoutReconnect = true;
                          try {
                            CallTrace("   try to auto reconnect");
                            Connect();

                            CallTrace("   reconnect successful, try to resend command");
                            CallTrace("Tx '{0}'", command);
                            pop3Stream.Write(commandBytes, 0, commandBytes.Length);
                          } finally {
                            isTimeoutReconnect = false;
                          }
                          return;
                        }
                      }
                    }
                    throw;
                  }
                  pop3Stream.Flush();
                }
             */


            /// <summary>
            /// read single line response from POP3 server. 
            /// <example>Example server response: +OK asdfkjahsf</example>
            /// </summary>
            /// <param name="response">response from POP3 server</param>
            /// <returns>true: positive response</returns>
            protected bool readSingleLine(out string response)
            {
                response = null;
                try
                {
                    response = pop3StreamReader.ReadLine();
                }
                catch (Exception ex)
                {
                    string s = ex.Message;
                }
                if (response == null)
                {
                    throw new Pop3Exception("Server " + popServer + " has not responded, timeout has occured.");
                }
                CallTrace("Rx '{0}'", response);
                return (response.Length > 0 && response[0] == '+');
            }


            /// <summary>
            /// read one line in multiline mode from the POP3 server. 
            /// </summary>
            /// <param name="response">line received</param>
            /// <returns>false: end of message</returns>
            /// <returns></returns>
            protected bool readMultiLine(out string response)
            {
                response = null;
                response = pop3StreamReader.ReadLine();
                if (response == null)
                {
                    throw new Pop3Exception("Server " + popServer + " has not responded, probably timeout has occured.");
                }
                if (isTraceRawEmail)
                {
                    //collect all responses as received
                    RawEmailSB.Append(response + CRLF);
                }
                //check for byte stuffing, i.e. if a line starts with a '.', another '.' is added, unless
                //it is the last line
                if (response.Length > 0 && response[0] == '.')
                {
                    if (response == ".")
                    {
                        //closing line found
                        return false;
                    }
                    //remove the first '.'
                    response = response.Substring(1, response.Length - 1);
                }
                return true;
            }

            #region | IDisposable Members |
            public void Dispose()
            {
                Disconnect();
            }
            #endregion | IDisposable Members |
        }
    }
    /// <summary>
    /// This class adds a few internet mail headers not already exposed by the
    /// System.Net.MailMessage.  It also provides support to encapsulate the
    /// nested mail attachments in the Children collection.
    /// </summary>
    public class MailMessageEx : MailMessage
    {
        public const string EmailRegexPattern = "(['\"]{1,}.+['\"]{1,}\\s+)?<?[\\w\\.\\-]+@[^\\.][\\w\\.\\-]+\\.[a-z]{2,}>?";

        private long _octets;

        public long Octets
        {
            get { return _octets; }
            set { _octets = value; }
        }

        private int _messageNumber;

        /// <summary>
        /// Gets or sets the message number for the MailMessage on the POP3 server.
        /// </summary>
        /// <value>The message number.</value>
        public int MessageNumber
        {
            get { return _messageNumber; }
            internal set { _messageNumber = value; }
        }


        private static readonly char[] AddressDelimiters = new char[] { ',', ';' };

        private List<MailMessageEx> _children;
        /// <summary>
        /// Gets the children MailMessage attachments.
        /// </summary>
        /// <value>The children MailMessage attachments.</value>
        public List<MailMessageEx> Children
        {
            get
            {
                return _children;
            }
        }

        public string PlainTextBody
        {
            get
            {
                if (ContentType.MediaType == Mime.MediaTypes.TextPlain)
                    return Body;

                //Otherwise, find the text/plain mime part and return it's content
                foreach (AlternateView view in AlternateViews)
                {
                    if (view.ContentType.MediaType == Mime.MediaTypes.TextPlain)
                    {
                        System.IO.StreamReader rdr = new System.IO.StreamReader(view.ContentStream);
                        return (rdr.ReadToEnd());
                    }
                }


                //No Plain Text part was found, return an empty string
                return "";
            }
        }

        /// <summary>
        /// Gets the delivery date.
        /// </summary>
        /// <value>The delivery date.</value>
        public DateTime DeliveryDate
        {
            get
            {
                string date = GetHeader(MailHeaders.Date);
                if (string.IsNullOrEmpty(date))
                {
                    return DateTime.MinValue;
                }

                return Convert.ToDateTime(date);
            }
        }

        /// <summary>
        /// Gets the return address.
        /// </summary>
        /// <value>The return address.</value>
        public MailAddress ReturnAddress
        {
            get
            {
                string replyTo = GetHeader(MailHeaders.ReplyTo);
                if (string.IsNullOrEmpty(replyTo))
                {
                    return null;
                }

                return CreateMailAddress(replyTo);
            }
        }

        /// <summary>
        /// Gets the routing.
        /// </summary>
        /// <value>The routing.</value>
        public string Routing
        {
            get { return GetHeader(MailHeaders.Received); }
        }

        /// <summary>
        /// Gets the message id.
        /// </summary>
        /// <value>The message id.</value>
        public string MessageId
        {
            get { return GetHeader(MailHeaders.MessageId); }
        }

        public string ReplyToMessageId
        {
            get { return GetHeader(MailHeaders.InReplyTo, true); }
        }

        /// <summary>
        /// Gets the mime version.
        /// </summary>
        /// <value>The mime version.</value>
        public string MimeVersion
        {
            get { return GetHeader(Mime.MimeHeaders.MimeVersion); }
        }

        /// <summary>
        /// Gets the content id.
        /// </summary>
        /// <value>The content id.</value>
        public string ContentId
        {
            get { return GetHeader(Mime.MimeHeaders.ContentId); }
        }

        /// <summary>
        /// Gets the content description;
        /// </summary>
        /// <value>The content description.</value>
        public string ContentDescription
        {
            get { return GetHeader(Mime.MimeHeaders.ContentDescription); }
        }

        /// <summary>
        /// Gets the content disposition.
        /// </summary>
        /// <value>The content disposition.</value>
        public ContentDisposition ContentDisposition
        {
            get
            {
                string contentDisposition = GetHeader(Mime.MimeHeaders.ContentDisposition);
                if (string.IsNullOrEmpty(contentDisposition))
                {
                    return null;
                }

                return new ContentDisposition(contentDisposition);
            }
        }

        /// <summary>
        /// Gets the type of the content.
        /// </summary>
        /// <value>The type of the content.</value>
        public ContentType ContentType
        {
            get
            {
                string contentType = GetHeader(Mime.MimeHeaders.ContentType);
                if (string.IsNullOrEmpty(contentType))
                {
                    return null;
                }

                return Mime.MimeReader.GetContentType(contentType);
            }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="MailMessageEx"/> class.
        /// </summary>
        public MailMessageEx()
            : base()
        {
            _children = new List<MailMessageEx>();
        }

        /// <summary>
        /// Gets the header.
        /// </summary>
        /// <param name="header">The header.</param>
        /// <returns></returns>
        private string GetHeader(string header)
        {
            return GetHeader(header, false);
        }

        private string GetHeader(string header, bool stripBrackts)
        {
            if (stripBrackts)
            {
                return Mime.MimeEntity.TrimBrackets(Headers[header]);
            }

            return Headers[header];
        }

        /// <summary>
        /// Creates the mail message from entity.
        /// </summary>
        /// <param name="entity">The entity.</param>
        /// <returns></returns>
        public static MailMessageEx CreateMailMessageFromEntity(Mime.MimeEntity entity)
        {
            MailMessageEx message = new MailMessageEx();
            string value;
            foreach(string key in entity.Headers.AllKeys)
            {
                value = entity.Headers[key];
                if (value.Equals(string.Empty))
                {
                    value = " ";
                }

                message.Headers.Add(key.ToLowerInvariant(), value);

                switch (key.ToLowerInvariant())
                {
                    case MailHeaders.Bcc:
                        MailMessageEx.PopulateAddressList(value, message.Bcc);
                        break;
                    case MailHeaders.Cc:
                        MailMessageEx.PopulateAddressList(value, message.CC);
                        break;
                    case MailHeaders.From:
                        message.From = MailMessageEx.CreateMailAddress(value);
                        break;
                    case MailHeaders.ReplyTo:
                        message.ReplyTo = MailMessageEx.CreateMailAddress(value);
                        break;
                    case MailHeaders.Subject:
                        message.Subject = value;
                        break;
                    case MailHeaders.To:
                        MailMessageEx.PopulateAddressList(value, message.To);
                        break;
                }
            }

            return message;
        }

        /// <summary>
        /// Creates the mail address
        /// </summary>
        /// <param name="address">The address</param>
        /// <returns></returns>
        public static MailAddress CreateMailAddress(string address)
        {
            try
            {
                return new MailAddress(address.Trim('\t'));
            }
            catch (FormatException e)
            {
                throw new ApplicationException("Unable to create mail address from provided string: " + address, e);
            }
        }

        /// <summary>
        /// Populates the address list.
        /// </summary>
        /// <param name="addressList">The address list.</param>
        /// <param name="recipients">The recipients.</param>
        public static void PopulateAddressList(string addressList, MailAddressCollection recipients)
        {
            foreach (MailAddress address in GetMailAddresses(addressList))
            {
                recipients.Add(address);
            }
        }

        public static IEnumerable<MailAddress> GetMailAddresses(string addressList)
        {
            Regex email = new Regex(EmailRegexPattern);

            foreach (Match match in email.Matches(addressList))
            {
                yield return CreateMailAddress(match.Value);
            }


            /*
            string[] addresses = addressList.Split(AddressDelimiters);
            foreach (string address in addresses)
            {
                yield return CreateMailAddress(address);
            }*/
        }
    }
    public static class MailHeaders
    {
        public const string Bcc = "bcc";

        public const string Cc = "cc";

        public const string Date = "date";

        public const string From = "from";

        public const string Importance = "importance";

        public const string InReplyTo = "in-reply-to";

        public const string MessageId = "message-id";

        public const string Received = "received";

        public const string ReplyTo = "reply-to";

        public const string Subject = "subject";

        public const string To = "to";
    }
}