// Copyright (c) 2017 schick Informatik
// Description: Bool'sche Werte für Bindings invertieren
//

using System;
using System.Windows.Data;
using System.Windows.Markup;

namespace ENI2.Util
{

    [ValueConversion(typeof(bool?), typeof(bool?))]
    public class InverseBooleanConverter : MarkupExtension, IValueConverter
    {

        private static InverseBooleanConverter _converter = null;
        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            if (_converter == null)
            {
                _converter = new InverseBooleanConverter();
            }
            return _converter;
        }

        #region IValueConverter Members

        public object Convert(object value, Type targetType, object parameter,
            System.Globalization.CultureInfo culture)
        {
            if (targetType != typeof(bool?))
                throw new InvalidOperationException("The target must be a boolean");

            if (!((bool?)value).HasValue) return null;

            return !(bool?)value;
        }

        public object ConvertBack(object value, Type targetType, object parameter,
            System.Globalization.CultureInfo culture)
        {
            if (targetType != typeof(bool?))
                throw new InvalidOperationException("The target must be a boolean");

            if (!((bool?)value).HasValue) return null;

            return !(bool?)value;
        }

        #endregion
    }
}