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

namespace Bowin.Common.Utility
{
    /// <summary>
    /// Enum 的扩展
    /// </summary>
    public static class EnumExtension
    {
        private static ConcurrentDictionary<string, string> _cache = new ConcurrentDictionary<string, string>();

        public static string GetDisplayName(this Enum source)
        {
            var enumType = source.GetType();
            string name = Enum.GetName(enumType, source);
            var key = string.Concat(enumType.Name, "-", name);

            if (_cache.ContainsKey(key))
            {
                return _cache[key];
            }
            
            var enumDisplay = source.GetAttribute<DisplayAttribute>();

            if (enumDisplay != null)
            {
                _cache[key] = enumDisplay.Name;

                return enumDisplay.Name;
            }

            var enumDescription = source.GetAttribute<DescriptionAttribute>();

            if (enumDescription != null)
            {
                _cache[key] = enumDescription.Description;

                return enumDescription.Description;
            }

            _cache[key] = source.ToString();

            return source.ToString();
        }

        public static T GetAttribute<T>(this Enum source) where T : Attribute
        {
            Type enumType = source.GetType();
            string name = Enum.GetName(enumType, source);

            if (name != null)
            {
                FieldInfo fieldInfo = enumType.GetField(name);

                if (fieldInfo != null)
                {
                    return fieldInfo.GetAttribute<T>();
                }
            }

            return null;
        }
    }
}