using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Data;

namespace Tango.SharedUI.Converters
{
    /// <summary>
    /// Represents a binding converter for converting enum value to the associated description attribute if found.
    /// </summary>
    /// <seealso cref="System.Windows.Data.IValueConverter" />
    public class EnumToDescriptionConverter : IValueConverter
    {
        /// <summary>
        /// Converts a value.
        /// </summary>
        /// <param name="value">The value produced by the binding source.</param>
        /// <param name="targetType">The type of the binding target property.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// A converted value. If the method returns null, the valid null value is used.
        /// </returns>
        /// <exception cref="System.NotImplementedException"></exception>
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (value != null)
            {
                return GetDescription(value, value.ToString());
            }
            else
            {
                return null;
            }
        }

        public static string GetDescription(object enumValue, string defDesc)
        {
            FieldInfo fi = enumValue.GetType().GetField(enumValue.ToString());

            if (null != fi)
            {
                object[] attrs = fi.GetCustomAttributes(typeof(DescriptionAttribute), true);
                if (attrs != null && attrs.Length > 0)
                    return ((DescriptionAttribute)attrs[0]).Description;
            }

            return defDesc;
        }

        /// <summary>
        /// Converts a value.
        /// </summary>
        /// <param name="value">The value that is produced by the binding target.</param>
        /// <param name="targetType">The type to convert to.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// A converted value. If the method returns null, the valid null value is used.
        /// </returns>
        /// <exception cref="System.NotImplementedException"></exception>
        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return value;
        }
    }
}