namespace Yw.WinFrmUI
{
    /// <summary>
    /// 枚举在propertyGrid中的显示
    /// </summary>
    public class EnumPropertyConverter : ExpandableObjectConverter
    {
        /// <summary>  
        /// 构造函数  
        /// </summary>  
        public EnumPropertyConverter()
        {
            _dict = new Dictionary<object, string>();
        }

        private Dictionary<object, string> _dict;//枚举项集合

        /// <summary>  
        /// 加载枚举项集合  
        /// </summary>  
        private void LoadDict(ITypeDescriptorContext context)
        {
            _dict = GetEnumValueDispDict(context.PropertyDescriptor.PropertyType);
        }

        /// <summary>  
        /// 是否可从来源转换  
        /// </summary>  
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
        {
            if (sourceType == typeof(string))
            {
                return true;
            }

            return base.CanConvertFrom(context, sourceType);
        }

        /// <summary>  
        /// 从来源转换  
        /// </summary>  
        public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
        {
            if (value is string)
            {
                //如果是枚举  
                if (context.PropertyDescriptor.PropertyType.IsEnum)
                {
                    if (_dict.Count <= 0)
                        LoadDict(context);
                    if (_dict.Values.Contains(value.ToString()))
                    {
                        foreach (object obj in _dict.Keys)
                        {
                            if (_dict[obj] == value.ToString())
                            {
                                return obj;
                            }
                        }
                    }
                }
            }

            return base.ConvertFrom(context, culture, value);
        }

        /// <summary>  
        /// 是否可转换  
        /// </summary>  
        public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
        {
            return true;
        }

        /// <summary>
        /// 
        /// </summary>
        public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
        {
            return true;
        }

        /// <summary>
        /// 
        /// </summary>
        public override bool GetStandardValuesExclusive(ITypeDescriptorContext context)
        {
            return true;
        }

        /// <summary>
        /// 
        /// </summary>
        public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
        {
            if (_dict == null || _dict.Count <= 0)
                LoadDict(context);

            StandardValuesCollection vals = new TypeConverter.StandardValuesCollection(_dict.Keys);

            return vals;
        }

        /// <summary>
        /// 
        /// </summary>
        public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)
        {
            if (_dict.Count <= 0)
                LoadDict(context);

            foreach (object key in _dict.Keys)
            {
                if (key.ToString() == value.ToString() || _dict[key] == value.ToString())
                {
                    return _dict[key].ToString();
                }
            }

            return base.ConvertTo(context, culture, value, destinationType);
        }

        /// <summary>  
        /// 记载枚举的值+Display  
        /// </summary>  
        /// <param name="enumType"></param>  
        /// <returns></returns>  
        public Dictionary<object, string> GetEnumValueDispDict(Type enumType)
        {
            Dictionary<object, string> dict = new Dictionary<object, string>();
            FieldInfo[] fieldinfos = enumType.GetFields();
            foreach (FieldInfo field in fieldinfos)
            {
                if (field.FieldType.IsEnum)
                {
                    Object[] objs = field.GetCustomAttributes(typeof(DisplayAttribute), false);
                    if (objs.Length > 0)
                    {
                        dict.Add(Enum.Parse(enumType, field.Name), ((DisplayAttribute)objs[0]).Name);
                    }
                }

            }

            return dict;
        }

    }
}