public interface IAlertDialogHandler : IDialogHandler
{
    string Message { get; }
    bool Exists();
    void ClickOK();
    void WaitUntilExists();
    void WaitUntilExists(int waitInSeconds);
}

public interface IConfirmDialogHandler : IAlertDialogHandler
{
    void ClickCancel();
}

public class FirefoxAlertDialogHandler : IAlertDialogHandler
{
    private const string FindDialogWindowIdScript = @"for (i = 0; i < getWindows().length; i++) {
  if (getWindows()[i].location.toString().indexOf('commonDialog.xul') >= 0) {
    i;
    break;
  } else {
    -1;
  }
}";

    private const string DialogHasCorrectButtonsScript = "typeof getWindows()[{0}].document.documentElement.getButton('accept') !== 'undefined' && typeof getWindows()[{0}].document.documentElement.getButton('cancel') !== 'undefined' && getWindows()[{0}].document.documentElement.getButton('cancel').hidden;";
    private const string ClickOKButtonScript = "typeof getWindows()[{0}].document.documentElement.getButton('accept').click()";
    private const string WindowClassName = "MozillaDialogClass";

    private string _message = string.Empty;

    FFDocument _nativeDocument;
    int _windowIndex = -1;

    public FirefoxAlertDialogHandler(DomContainer hostBrowser)
    {
        FireFox hostFirefoxInstance = hostBrowser as FireFox;
        if (hostFirefoxInstance != null)
        {
            _nativeDocument = hostFirefoxInstance.NativeDocument as FFDocument;
        }
    }

    protected FFDocument NativeDocument
    {
        get { return _nativeDocument; }
    }

    protected virtual string HasCorrectButtonsScript
    {
        get { return DialogHasCorrectButtonsScript; }
    }

    protected int WindowIndex
    {
        get 
        {
            if (_nativeDocument != null && _windowIndex == -1)
            {
                _windowIndex = _nativeDocument.ClientPort.WriteAndReadAsInt(FindDialogWindowIdScript);
            }

            return _windowIndex; 
        }
    }

    protected bool HasCorrectButtons
    {
        get 
        {
            bool hasButtons = false;
            if (_nativeDocument != null)
            {
                hasButtons = _nativeDocument.ClientPort.WriteAndReadAsBool(HasCorrectButtonsScript, WindowIndex);
            }

            return hasButtons;
        }
    }

    public string Message
    {
        get { return _message; }
    }

    public bool Exists()
    {
        return WindowIndex >= 0 && HasCorrectButtons;
    }

    public void ClickOK()
    {
        if (_nativeDocument != null)
        {
            _nativeDocument.ClientPort.WriteAndRead(ClickOKButtonScript, WindowIndex);
        }
    }

    public void WaitUntilExists()
    {
        WaitUntilExists(30);
    }

    public void WaitUntilExists(int waitDurationInSeconds)
    {
        var tryActionUntilTimeOut = new TryFuncUntilTimeOut(TimeSpan.FromSeconds(waitDurationInSeconds));
        tryActionUntilTimeOut.Try(() => Exists());

        if (!Exists())
        {
            throw new WatiNException(string.Format("Dialog not available within {0} seconds.", waitDurationInSeconds));
        }
    }

    #region IDialogHandler Members
    public bool CanHandleDialog(WatiN.Core.Native.Windows.Window window, IntPtr mainWindowHwnd)
    {
        bool canHandle = false;
        if (window.ClassName == WindowClassName)
        {
            canHandle = Exists();
        }

        return canHandle;
    }

    public bool HandleDialog(WatiN.Core.Native.Windows.Window window)
    {
        while (window.Exists())
        {
            Thread.Sleep(200);
        }

        return true;
    }

    #endregion
}

public class FirefoxConfirmDialogHandler : FirefoxAlertDialogHandler, IConfirmDialogHandler
{
    private const string DialogHasCorrectButtonsScript = "typeof getWindows()[{0}].document.documentElement.getButton('accept') !== 'undefined' && typeof getWindows()[{0}].document.documentElement.getButton('cancel') !== 'undefined';";
    private const string ClickCancelButtonScript = "getWindows()[{0}].document.documentElement.getButton('cancel').click()";

    public FirefoxConfirmDialogHandler(DomContainer hostBrowser)
        : base(hostBrowser)
    {
    }

    protected override string HasCorrectButtonsScript
    {
        get { return DialogHasCorrectButtonsScript; }
    }

    public void ClickCancel()
    {
        NativeDocument.ClientPort.WriteAndRead(ClickCancelButtonScript, WindowIndex);
    }
}

public class IEAlertDialogHandler : AlertDialogHandler, IAlertDialogHandler
{
    public void ClickOK()
    {
        this.OKButton.Click();
    }
}

public class IEConfirmDialogHandler : ConfirmDialogHandler, IConfirmDialogHandler
{
    public void ClickCancel()
    {
        this.CancelButton.Click();
    }

    public void ClickOK()
    {
        this.OKButton.Click();
    }
}