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

namespace Services.Extensions
{
    /// <summary>
    /// 枚举扩展
    /// </summary>
    public static class EnumerableExtensions
    {
        /// <summary>
        /// 对枚举器的每个元素执行指定的操作
        /// </summary>
        /// <typeparam name="T">枚举器类型参数</typeparam>
        /// <param name="source">枚举器</param>
        /// <param name="action">要对枚举器的每个元素执行的委托</param>
        public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)
        {
            if (source.IsNullOrEmpty<T>() || action == null)
            {
                return;
            }
            foreach (T obj in source)
            {
                action(obj);
            }
        }

        /// <summary>
        /// 指示指定的枚举器是null还是没有任何元素
        /// </summary>
        /// <typeparam name="T">枚举器类型参数</typeparam>
        /// <param name="source">要测试的枚举器</param>
        /// <returns>true:枚举器是null或者没有任何元素 false:枚举器不为null并且包含至少一个元素</returns>
        public static bool IsNullOrEmpty<T>(this IEnumerable<T> source)
        {
            return source == null || !source.Any<T>();
        }

        /// <summary>
        /// 得到枚举中文备注
        /// </summary>
        /// <param name="enumValue"></param>
        /// <returns></returns>
        public static string GetEnumDesc(this System.Enum enumValue)
        {
            string value = enumValue.ToString();
            System.Reflection.FieldInfo field = enumValue.GetType().GetField(value);
            object[] objs = field.GetCustomAttributes(typeof(DescriptionAttribute), false);    //获取描述属性
            if (objs.Length == 0)    //当描述属性没有时，直接返回名称
                return value;
            DescriptionAttribute descriptionAttribute = (DescriptionAttribute)objs[0];
            return descriptionAttribute.Description;
        }

        public static string GetEnumDesc(this Type enumType, object val)
        {
            string enumvalue = Enum.GetName(enumType, val);
            if (string.IsNullOrEmpty(enumvalue))
            {
                return "";
            }
            FieldInfo finfo = enumType.GetField(enumvalue);
            object[] enumAttr = finfo.GetCustomAttributes(typeof(DescriptionAttribute), true);
            if (enumAttr.Length > 0)
            {
                DescriptionAttribute desc = (DescriptionAttribute)enumAttr[0];
                if (desc != null)
                {
                    return desc.Description;
                }
            }
            return enumvalue;
        }

        /// <summary>
        /// 获取所有的枚举描述和值
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        public static List<EnumDto> GetEnumListItem(this Type type)
        {

            List<EnumDto> list = new List<EnumDto>();

            // 循环枚举获取所有的Fields
            foreach (var field in type.GetFields())
            {
                // 如果是枚举类型
                if (field.FieldType.IsEnum)
                {
                    object tmp = field.GetValue(null);
                    Enum enumValue = (Enum)tmp;
                    int intValue = Convert.ToInt32(enumValue);
                    string showName = enumValue.GetEnumDesc(); // 获取描述和排序
                    list.Add(new EnumDto { Value = intValue, Description = showName });
                }
            }
            //返回
            return list;

        }

        public class EnumDto
        {
            /// <summary>
            /// 枚举code
            /// </summary>
            public string Code { get; set; }

            /// <summary>
            /// 值
            /// </summary>
            public int Value { get; set; }

            /// <summary>
            /// 描述
            /// </summary>
            public string Description { get; set; }
        }

    }

}