﻿/*
 * Copyright © 2010, Denys Vuika
 * Copyright © 2014, Kastellanos Nikolaos
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *  http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

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

namespace tainicom.WpfPropertyGrid
{  
  /// <summary>
  /// Default enum converter.
  /// </summary>
  // See more details here http://www.codeproject.com/KB/WPF/FriendlyEnums.aspx
  [ValueConversion(typeof(object), typeof(string))]
  public class EnumValueConverter : IValueConverter
  {
    /// <summary>
    /// Default string presenting a null value.
    /// </summary>
    public const string NullValueString = "(null)";

    #region IValueConverter Members

    /// <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>
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
      if (value is Enum)
      {
        var fi = value.GetType().GetField(value.ToString());
        var attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
        return ((attributes.Length > 0) && (!String.IsNullOrEmpty(attributes[0].Description))) ? attributes[0].Description : value.ToString();
      }
      // return (null) in case enum value is not assigned...       
      // this is mainly for dependency properties as DP property may contain undefined enum
      // native CLR properties will always assign it according to the first value
      if (value == null)
      {
        return NullValueString;
      }
      else
      {
        return value.ToString();
      }
    }

    /// <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>
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
      throw new NotSupportedException();
    }

    #endregion
  }
}
