using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections.Concurrent;
using System.ComponentModel;

namespace Bowin.Common.Exceptions
{
    public class EnumHelper
    {
        static ConcurrentDictionary<Type, Dictionary<int, string>> _listItemCache =
            new ConcurrentDictionary<Type, Dictionary<int, string>>();

        /// <summary>
        /// 将枚举转换成Dictionary&lt;int, string&gt;
        /// Dictionary中，key为枚举项对应的int值；value为：若定义了Description属性，则取它，否则取name
        /// </summary>
        /// <param name="enumType"></param>
        /// <returns></returns>
        public static Dictionary<int, string> EnumToDictionary(Type enumType)
        {
            Dictionary<int, string> items;

            if (!_listItemCache.TryGetValue(enumType, out items))
            {
                items = new Dictionary<int, string>();

                foreach (int i in Enum.GetValues(enumType))
                {
                    var name = Enum.GetName(enumType, i);

                    //取显示名称
                    string showName = string.Empty;
                    object[] atts = enumType.GetField(name).GetCustomAttributes(typeof(DescriptionAttribute), false);

                    if (atts.Length > 0)
                        showName = ((DescriptionAttribute)atts[0]).Description;

                    items.Add(i, string.IsNullOrEmpty(showName) ? name : showName);
                }

                _listItemCache[enumType] = items;
            }

            return items;
        }

        /// <summary>
        /// 获取枚举值对应的显示名称
        /// </summary>
        /// <param name="enumType">枚举类型</param>
        /// <param name="value">枚举项对应的int值</param>
        /// <returns></returns>
        public static string GetEnumShowName(Type enumType, int value)
        {
            return EnumToDictionary(enumType)[value];
        }
    }
}