using System;
using System.Net;
using System.Net.Mail;
using System.Text.RegularExpressions;
using System.Threading;

namespace Server.Misc
{
  public class Email
  {
    /* In order to support emailing, fill in EmailServer and FromAddress:
     * Example:
     *  public static readonly string EmailServer = "mail.domain.com";
     *  public static readonly string FromAddress = "runuo@domain.com";
     * 
     * If you want to add crash reporting emailing, fill in CrashAddresses:
     * Example:
     *  public static readonly string CrashAddresses = "first@email.here,second@email.here,third@email.here";
     * 
     * If you want to add speech log page emailing, fill in SpeechLogPageAddresses:
     * Example:
     *  public static readonly string SpeechLogPageAddresses = "first@email.here,second@email.here,third@email.here";
     */

    public static readonly string EmailServer = null;
    public static readonly int EmailPort = 25;

    public static readonly string FromAddress = null;
    public static readonly string EmailUsername = null;
    public static readonly string EmailPassword = null;


    public static readonly string CrashAddresses = null;
    public static readonly string SpeechLogPageAddresses = null;

    private static Regex _pattern = new Regex(@"^[a-z0-9.+_-]+@([a-z0-9-]+\.)+[a-z]+$",
      RegexOptions.Compiled | RegexOptions.IgnoreCase);

    private static SmtpClient _Client;

    public static bool IsValid(string address)
    {
      if (address == null || address.Length > 320)
        return false;

      return _pattern.IsMatch(address);
    }

    public static void Configure()
    {
      if (EmailServer != null)
      {
        _Client = new SmtpClient(EmailServer, EmailPort);
        if (EmailUsername != null) _Client.Credentials = new NetworkCredential(EmailUsername, EmailPassword);
      }
    }

    public static bool Send(MailMessage message)
    {
      try
      {
        // .NET relies on the MTA to generate Message-ID header. Not all MTAs will add this header.

        DateTime now = DateTime.UtcNow;
        string messageID = $"<{now.ToString("yyyyMMdd")}.{now.ToString("HHmmssff")}@{EmailServer}>";
        message.Headers.Add("Message-ID", messageID);

        message.Headers.Add("X-Mailer", "RunUO");

        lock (_Client)
        {
          _Client.Send(message);
        }
      }
      catch
      {
        return false;
      }

      return true;
    }

    public static void AsyncSend(MailMessage message)
    {
      ThreadPool.QueueUserWorkItem(SendCallback, message);
    }

    private static void SendCallback(object state)
    {
      MailMessage message = (MailMessage)state;

      if (Send(message))
        Console.WriteLine("Sent e-mail '{0}' to '{1}'.", message.Subject, message.To);
      else
        Console.WriteLine("Failure sending e-mail '{0}' to '{1}'.", message.Subject, message.To);
    }
  }
}