using System;
using System.Data;
using System.Configuration;
using System.Net;
using System.Net.Mail;
using System.Collections.Generic;
using System.Timers;

/// <summary>
/// 郵件傳送服務
/// </summary>
public class WMailSender
{
  private static WMailSender _instance = null;
  private Queue<MailMessage> _queue = null;
  private bool _enabled = false;
  private int _interval = 30;
  private Timer _timer = null;
  private string _host = "";

  private WMailSender()
  {
    _queue = new Queue<MailMessage>();

    _timer = new Timer();
    _timer.Enabled = false;
    _timer.Elapsed += new ElapsedEventHandler(SendMailLoop);
  }

  public static WMailSender GetInstance()
  {
    if (_instance == null)
      _instance = new WMailSender();
    return _instance;
  }

  public string Host
  {
    set
    {
      _host = value;
    }
    get
    {
      return _host;
    }
  }

  public void Send(MailMessage message)
  {
    _queue.Enqueue(message);
  }

  private void SendMailLoop(object sender, ElapsedEventArgs e)
  {
    if (!_enabled)
    {
      _timer.Enabled = false;
      return;
    }

    _timer.Enabled = false;

    SmtpClient _client = new SmtpClient();
    //_client.DeliveryMethod = SmtpDeliveryMethod.Network;

    try
    {
      while (_queue.Count > 0)
      {
        MailMessage message = _queue.Dequeue();
        try
        {
          _client.Send(message);
        }
        catch
        {
          // 如果傳送失敗，需重傳
          _queue.Enqueue(message);
        }
      }
    }
    finally
    {
      _timer.Enabled = true;
    }
  }

  public int Interval
  {
    get
    {
      return _interval;
    }
    set
    {
      _interval = value;
    }
  }

  public bool Enabled
  {
    get
    {
      return _enabled;
    }
    set
    {
      if (value)
      {
        if (_enabled)
          return;

        _timer.Interval = _interval * 1000;
        _timer.AutoReset = true;
        _timer.Enabled = true;
        _enabled = true;
      }
      else
      {
        if (!_enabled)
          return;

        _enabled = false;
        _timer.Enabled = false;
      }
    }
  }
}