using System.Net.Sockets;
using System.Collections;
using System.IO;
using System.Net;
using System;
using System.Web.Mail;

 public class POP3
 {
  string POPServer;
  string user;
  string pwd;
  NetworkStream ns;
  StreamReader sr;
  static int  count;
  //调用Srfile类，写入文件内容和文件名,文件格式：.txt 读邮件信息
  // Srfile  Filesr = new Srfile();

  //对邮件标题 base64 解码
  /// <summary>
  /// base64 解码
  /// </summary>
  /// <param name="code"></param>
  /// <returns></returns>
  private string DecodeBase64(string code)  //string code_type,
  {
   string decode = "";
   string st = code+"000";//
   string   strcode = st.Substring(0,(st.Length/4)*4);
   byte[] bytes = Convert.FromBase64String(strcode);
   try
   {
    decode = System.Text.Encoding.GetEncoding("GB2312").GetString(bytes);
   }
   catch
   {
    decode = code;
   }
   return decode;
  }
 
  //对邮件标题解码  quoted-printable
  /// <summary>
  ///  quoted-printable  解码
  /// </summary>
  /// <param name="code"></param>
  /// <returns></returns>
  private  string  DecodeQ(string code)
  {
       
   string[] textArray1 = code.Split(new char[] { '=' });
   byte[] buf = new byte[textArray1.Length];
   try
   {
  
    for (int i =0;i<textArray1.Length;i++)
    {
     if (textArray1[i].Trim()!=string.Empty)
     {
   
      byte[]  buftest = new byte[2];
            
      buf[i] = (byte) int.Parse(textArray1[i].Substring(0,2),System.Globalization.NumberStyles.HexNumber);

     }
    }
   }
   catch
   {
    return null;
   }
   return System.Text.Encoding.Default.GetString(buf);
  }

  public POP3(){}

  #region
  /// <summary>
  /// 接收邮件服务器相关信息
  /// </summary>
  /// <param name="server">参数 pop邮件服务器地址  </param>
  /// <param name="user">参数 登录到pop邮件服务器的用户名  </param>
  /// <param name="pwd">参数  登录到pop邮件服务器的密码</param>
  /// <returns>无返回</returns>
  public POP3(string server, string _user, string _pwd)
  {
   POPServer = server;
   user = _user;
   pwd = _pwd;
  }
  #endregion
  //登陆服务器
  private void Connect()
  {
   TcpClient sender = new TcpClient(POPServer,110);
   Byte[] outbytes;
   string input;
   string  readuser = string.Empty;
   string  readpwd = string.Empty;
   try
   {
    ns = sender.GetStream();
    sr = new StreamReader(ns);
    sr.ReadLine();
    //检查密码
    input = "user " + user + "\r\n";
    outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length) ;

    readuser = sr.ReadLine();
    input = "pass " + pwd + "\r\n";
    outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length) ;
    readpwd = sr.ReadLine();
    //Console.WriteLine(sr.ReadLine() );
    
   }
   catch
   {
    System.Windows.Forms.MessageBox.Show("用户名或密码错误");
   }
  }
  //为了读到数据流中的正确信息，重新建的一个方法（只是在读邮件详细信息是用到《即GetNewMessages（）方法中用到，这样就可以正常显示邮件正文的中英文》）
  private  void Connecttest(TcpClient  tcpc)
  {
   Byte[] outbytes;
   string input;
   string  readuser = string.Empty;
   string  readpwd = string.Empty;
   try
   {
    ns = tcpc.GetStream();
    sr = new StreamReader(ns);

    sr.ReadLine();
    //Console.WriteLine(sr.ReadLine() );

    input = "user " + user + "\r\n";
    outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length) ;

   
    readuser = sr.ReadLine();
  
    input = "pass " + pwd + "\r\n";
    outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length) ;
    readpwd = sr.ReadLine();

   }
   catch
   {
    System.Windows.Forms.MessageBox.Show("用户名或密码错误");
   }
  }
  //断开与服务器的连接
  private void Disconnect()
  {
   //"quit"  即表示断开连接
   string input = "quit" + "\r\n";
   Byte[] outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
   ns.Write(outbytes,0,outbytes.Length);
   //关闭数据流
   ns.Close();
  }
  //获得新邮件数目
  # region
  /// <summary>
  /// 获取邮件数目
  /// </summary>
  /// <returns>返回  int  邮件数目</returns>
  public int GetNumberOfNewMessages()
  {
   Byte[] outbytes;
   string input;

   int  countmail;

   try
   {
    Connect();
    //"stat"向邮件服务器 表示要取邮件数目
    input = "stat" + "\r\n";
    //将string input转化为7位的字符，以便可以在网络上传输
    outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length);
    string thisResponse = sr.ReadLine();
    if (thisResponse.Substring(0,4) == "-ERR")
    {
     return  -1;
    }
    string[] tmpArray;
    //将从服务器取到的数据以“”分成字符数组
    tmpArray=thisResponse.Split(' ');
    //断开与服务器的连接
    Disconnect();
    //取到的表示邮件数目
    countmail = Convert.ToInt32(tmpArray[1]);
    count = countmail;
    return countmail;

   }
   catch
   {
    System.Windows.Forms.MessageBox.Show("Could not connect to mail server");
    return -1;//表示读邮件时  出错，将接收邮件的线程 阻塞5分钟
   }
  }
  # endregion
   
  //获取邮件
  # region
  /// <summary>
  /// 获取所有新邮件
  /// </summary>
  /// <returns>  返回 ArrayList</returns>

  public ArrayList  GetNewMessages( )   //public ArrayList  GetNewMessages(string subj)
  {
 
   bool  blag = false;
   int newcount = GetNumberOfNewMessages();
   ArrayList newmsgs = new ArrayList();

   try
   {
    TcpClient  tcpc = new TcpClient(POPServer,110);
    Connecttest(tcpc);
    //   newcount = GetNumberOfNewMessages();

    for(int n =1; n<newcount+1; n++)
    {
     ArrayList msglines = GetRawMessage(tcpc,n);
     string msgsubj = GetMessageSubject(msglines).Trim();

     System.Web.Mail.MailMessage msg = new MailMessage();

     //首先判断Substring是什么编码（"=?gb2312?B?"或者"=?gb2312?Q?"），然后转到相应的解码方法，实现解码
     //如果是"=?gb2312?B?"，转到DecodeBase64（）进行解码
     if (msgsubj.Length>11)
     {
      //base64编码
      if (msgsubj.Substring(0,11)=="=?gb2312?B?")
      {
       blag = true;

       msgsubj = msgsubj.Substring(11,msgsubj.Length-13);
       msg.Subject = DecodeBase64(msgsubj);
      }
      //如果是"=?gb2312?Q?"编码，先得取到被编码的部分，字符如果没编码就不转到解码方法
      if(msgsubj.Length>11)
      {

     
       if (msgsubj.Substring(0,11)=="=?gb2312?Q?")
       {
        blag = true;
        msgsubj = msgsubj.Substring(11,msgsubj.Length-13);
        string  text = msgsubj;
        string  str = string.Empty;
        string  decodeq = string.Empty;
        while(text.Length>0)
        {
         //判断编码部分是否开始
         if (text.Substring(0,1)=="=")
         {
          decodeq = text.Substring(0,3);
          text = text.Substring(3,text.Length-3);
          //当出现编码部分时，则取出连续的编码部分
          while (text.Length>0)
          {
           if(text.Substring(0,1) == "=")
           {
            decodeq +=text.Substring(0,3);
            text = text.Substring(3,text.Length-3);

           }
           else
           {
            break;
           }
          }
          //将连续的编码进行解码
          str += DecodeQ(decodeq);

         }
          //如果该字节没编码，则不用处理
         else
         {
          str += text.Substring(0,1);
          text = text.Substring(1,text.Length-1);
         }
      
        }
        //用空格代替subject中的“\0”,以便能取道全部的内容
        msg.Subject = str.Replace("\0"," ");
       }
      }
      if (blag == false)
      {
       msg.Subject = msgsubj.Replace("\0"," ");
      }
     
   
     }
     else
     {
      msg.Subject = msgsubj.Replace("\0"," ");
     }

     blag = false;

     //取发邮件者的邮件地址 
     msg.From = GetMessageFrom(msglines);
     //取邮件正文
     string  msgbody = GetMessageBody(msglines);
     msg.Body = msgbody;
     newmsgs.Add(msg);
    
     //将收到的邮件保存到本地，调用另一个类的保存邮件方法，不使用此功能
     //    Filesr.Savefile("subject:"+msg.Subject+"\r\n"+"sender:"+msg.From+"\r\n"+"context:"+msg.Body,"mail"+n+".txt");
     //删除邮件，不使用
     //       DeleteMessage(n);
    }
    //断开与服务器的连接
    Disconnect();
    return newmsgs;
   }
   catch
   {
//    System.Windows.Forms.MessageBox.Show("读取邮件出错，请重试");
    return newmsgs;
   }
  }
  #endregion
  //从服务器读邮件信息
  private ArrayList GetRawMessage (TcpClient  tcpc,int messagenumber)
  {
   Byte[] outbytes;
   string input;
   string line = "";
   input = "retr " + messagenumber.ToString() + "\r\n";
   outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
   ns.Write(outbytes,0,outbytes.Length);

   ArrayList msglines = new ArrayList();
   StreamReader  srtext;
   srtext = new StreamReader(tcpc.GetStream(),System.Text.Encoding.Default);
   //每份邮件以英文“.”结束
   do
   {
    line = srtext.ReadLine();
    msglines.Add(line);
   } while (line != ".");
   msglines.RemoveAt(msglines.Count-1);

   return msglines;
  }
  //获取邮件标题
  private string GetMessageSubject(ArrayList msglines)
  {
   IEnumerator msgenum = msglines.GetEnumerator();
   while (msgenum.MoveNext() )
   {
    string line = (string)msgenum.Current;
    if(line.StartsWith("Subject:") )
    {
     return line.Substring(8,line.Length-8);
    }
   }
   return "None";
  }
  //获取邮件的发送人地址
  private string GetMessageFrom (ArrayList msglines)
  {
   string[] tokens;
   IEnumerator msgenum = msglines.GetEnumerator();
   while (msgenum.MoveNext() )
   {
    string line = (string)msgenum.Current;
    if(line.StartsWith("From") )
    {
     tokens = line.Split(new Char[] {':'});
     return tokens[1].Trim(new Char[] {'<','>',' '});
    }
   }
   return "None";
  }

  //邮件正文
  private string GetMessageBody(ArrayList msglines)
  {
   string body = "";
   string line = " ";
   IEnumerator msgenum = msglines.GetEnumerator();

   while(line.CompareTo("") != 0)
   {
    msgenum.MoveNext();
    line = (string)msgenum.Current;
   }

   while (msgenum.MoveNext() )
   {
    body = body + (string)msgenum.Current + "\r\n";
   }
   return body;
  }
  //删除第几封邮件
  #region
  /// <summary>
  ///根据输入的数字，删除相应编号的邮件
  /// </summary>
  /// <param name="messagenumber">参数 删除第几封邮件  </param>
  /// <returns>返回  bool true成功；false  失败</returns>
  public bool DeleteMessage(int messagenumber)
  {
   Connect();
   Byte[] outbytes;
   string input ;
   byte[]  backmsg = new byte[25];
   string  msg = string.Empty;
  
   try
   {
    input = "dele " + messagenumber.ToString() + "\r\n";
    outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length);
    ns.Read(backmsg,0,25);
    msg = System.Text.Encoding.Default.GetString(backmsg,0,backmsg.Length);
    Disconnect();
    if (msg.Substring(0,3)=="+OK")
    {
     return  true;
    }
    return  false;
   }
   catch(Exception e)
   {
    return  false;
   }

  }
  #endregion

 }