using System;
using System.Globalization;
using System.Windows.Data;

namespace DTS.Common.Converters
{
    /// <summary>
    /// This converter is used to bind a value to a group of radio buttons, and can be used with bool parameters only. 
    /// It depends on the converter parameter, which maps a radio button to a specific value.
    /// </summary>
    /// 
    /// <remarks>
    /// <para>
    /// Notice the converter parameter. 
    /// Its role is to make sure to get opposite values for the two radio buttons (when one is true, the other is false).
    /// --------------------------------------------------------------------------------------------------
    /// | value	| param	| result : (RadioButton.IsChecked = !(value ^ param)) where ^ is the XOR operator |
    /// --------------------------------------------------------------------------------------------------
    /// | true	| true	| true                                                                            |
    /// | false	| true	| false                                                                           |
    /// | true	| false	| false                                                                           |
    /// | false	| false	| true                                                                            |
    /// --------------------------------------------------------------------------------------------------
    /// </para>
    /// </remarks> 
    [ValueConversion(typeof(bool?), typeof(bool))]
    public class RadioButtonCheckedConverter : IValueConverter
    {
        /// <summary>
        /// Maps a radio button to a specific value.
        /// </summary>
        /// <param name="value">The value produced by the binding source.</param>
        /// <param name="targetType">The target output type.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the format operation.</param>
        /// <returns>
        /// <value>
        /// <see langword="true" /> if [value] and [parameter] have same values; otherwise <see langword="false" />.
        /// </value>
        /// </returns>
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var param = bool.Parse(parameter.ToString());
            if (value == null)
                return false;

            return !((bool)value ^ param); // ^ is the XOR operator
        }

        /// <summary>
        /// Maps a radio button to a specific value.
        /// </summary>
        /// <param name="value">The value that is produced by the binding target.</param>
        /// <param name="targetType">This parameter is not used.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">This parameter is not used.</param>
        /// <returns>
        /// <value>
        /// <see langword="true" /> if [value] and [parameter] have same values; otherwise <see langword="false" />.
        /// </value>
        /// </returns>
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var param = bool.Parse(parameter.ToString());
            return !((bool)value ^ param);
        }
    }
}