using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Xml;

namespace Tiger.Model.Extensions
{
    /// <summary>
    /// 枚举扩展方法
    /// </summary>
    internal static class EnumExtension
    {
        /// <summary>
        /// 获得枚举的名称
        /// </summary>
        /// <returns>枚举的名称</returns>
        public static string GetName(this Enum obj)
        {
            return Enum.GetName(obj.GetType(), obj);
        }

        /// <summary>
        /// 获得枚举的值
        /// </summary>
        /// <returns>枚举的值</returns>
        public static int GetValue(this Enum obj)
        {
            return Convert.ToInt32(obj);
        }

        /// <summary>
        /// 获得枚举的描述，如果没有定义描述则使用枚举的名称代替
        /// </summary>
        /// <returns>枚举的描述</returns>
        public static string GetDesc(this Enum obj)
        {
            string name = Enum.GetName(obj.GetType(), obj);
            DescriptionAttribute attribute = obj.GetType().GetField(name).GetCustomAttribute(typeof(DescriptionAttribute), true) as DescriptionAttribute;
            return attribute?.Description ?? name;
        }


        /// <summary>
        /// 根据名称或者描述获取枚举对象
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="description"></param>
        /// <returns></returns>
        public static T GetEnum<T>(this string description) where T : struct
        {
            Type type = typeof(T);
            foreach (var field in type.GetFields())
            {
                if (field.Name == description)
                {
                    return (T)field.GetValue(null);
                }

                var attributes = (DescriptionAttribute[])field.GetCustomAttributes(typeof(DescriptionAttribute), true);
                if (attributes != null && attributes.FirstOrDefault() != null)
                {
                    if (attributes.First().Description == description)
                    {
                        return (T)field.GetValue(null);
                    }
                }
            }

            throw new ArgumentException($"{type.Name}中未能找到名称或者描述[{description}]对应的枚举.", "Description");
        }

        /// <summary>
        /// 根据值获取枚举对象
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="value"></param>
        /// <returns></returns>
        public static T GetEnum<T>(this int value) where T : struct
        {
            Type type = typeof(T);
            if (type.IsEnum)
            {
                return (T)Enum.Parse(type, value.ToString());
            }

            throw new TypeLoadException($"{type.Name}不是枚举类型");
        }

        /// <summary>
        /// 根据值获取枚举描述
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="value"></param>
        /// <returns></returns>
        public static string GetEnumDesc<T>(this int value) where T : struct
        {
            Type type = typeof(T);
            if (type.IsEnum)
            {
                return GetDesc((Enum)Enum.Parse(type, value.ToString()));
            }

            throw new TypeLoadException($"{type.Name}不是枚举类型");
        }

        /// <summary>
        /// 获取枚举内容列表
        /// </summary>
        /// <param name="type">枚举类型typeof(T)</param>
        /// <returns>返回枚举内容列表</returns>
        public static List<EnumContent> GetEnumContent(this Type type)
        {
            List<EnumContent> result = new List<EnumContent>();
            FieldInfo[] fields = type.GetFields();
            foreach (FieldInfo field in fields)
            {
                if (field.FieldType.IsEnum)
                {
                    object[] attr = field.GetCustomAttributes(typeof(DescriptionAttribute), false);
                    result.Add(new EnumContent(field.Name, Convert.ToInt32(field.GetValue(null)), attr.Length == 0 ? field.Name : ((DescriptionAttribute)attr[0]).Description));
                }
            }

            return result;
        }
    }

    /// <summary>
    /// 枚举内容实体
    /// </summary>
    internal readonly struct EnumContent
    {
        /// <summary>
        /// 枚举内容实体
        /// </summary>
        /// <param name="name">名称</param>
        /// <param name="value">值</param>
        /// <param name="desc">描述</param>
        public EnumContent(string name, int value, string desc)
        {
            Name = name;
            Value = value;
            Desc = desc;
        }
        /// <summary>
        /// 名称
        /// </summary>
        public string Name { get; }
        /// <summary>
        /// 值
        /// </summary>
        public int Value { get; }
        /// <summary>
        /// 描述
        /// </summary>
        public string Desc { get; }
    }
}