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

namespace Masuit.Tools.Systems;

/// <summary>
/// 枚举扩展类
/// </summary>
public static partial class EnumExt
{
    private static readonly ConcurrentDictionary<Type, Dictionary<int, string>> EnumNameValueDict = new();
    private static NullableDictionary<string, Type> _enumTypeDict;

    /// <summary>
    /// 获取枚举对象Key与显示名称的字典
    /// </summary>
    /// <param name="enumType"></param>
    /// <returns></returns>
    public static Dictionary<int, string> GetDictionary(this Type enumType)
    {
        if (!enumType.IsEnum)
        {
            throw new Exception("给定的类型不是枚举类型");
        }

        return EnumNameValueDict.GetOrAdd(enumType, _ => GetDictionaryItems(enumType));
    }

    private static Dictionary<int, string> GetDictionaryItems(Type enumType)
    {
        var enumItems = enumType.GetFields(BindingFlags.Public | BindingFlags.Static);
        var names = new Dictionary<int, string>(enumItems.Length);
        foreach (var enumItem in enumItems)
        {
            names[(int)enumItem.GetValue(enumType)] = enumItem.Name;
        }

        return names;
    }

    /// <summary>
    /// 获取枚举类型
    /// </summary>
    /// <param name="assembly"></param>
    /// <param name="typeName"></param>
    /// <returns></returns>
    public static Type GetEnumType(this Assembly assembly, string typeName)
    {
        _enumTypeDict ??= LoadEnumTypeDict(assembly);
        return _enumTypeDict[typeName];
    }

    /// <summary>
    /// 根据枚举成员获取Display的属性Name
    /// </summary>
    /// <returns></returns>
    public static string GetDisplay(this Enum en)
    {
        var type = en.GetType(); //获取类型
        var memberInfos = type.GetMember(en.ToString()); //获取成员
        if (memberInfos.Any() && memberInfos[0].GetCustomAttributes(typeof(DisplayAttribute), false) is DisplayAttribute[] attrs && attrs.Length > 0)
        {
            return attrs[0].Name; //返回当前描述
        }

        return en.ToString();
    }

    private static NullableDictionary<string, Type> LoadEnumTypeDict(Assembly assembly)
    {
        return assembly.GetTypes().Where(o => o.IsEnum).ToDictionarySafety(o => o.Name, o => o);
    }

    /// <summary>
    /// 获取枚举值的Description信息
    /// </summary>
    /// <param name ="value">枚举值</param>
    /// <param name ="args">要格式化的对象</param>
    /// <returns>如果未找到DescriptionAttribute则返回null或返回类型描述</returns>
    public static string GetDescription(this Enum value, params object[] args)
    {
        var type = value.GetType();
        if (!Enum.IsDefined(type, value))
        {
            return Enum.GetValues(type).OfType<Enum>().Where(value.HasFlag).Select(e =>
            {
                var member = type.GetField(e.ToString());
                var description = member.GetCustomAttributes(typeof(DescriptionAttribute), false) is DescriptionAttribute[] attrs && attrs.Length != 0 ? attrs[0].Description : e.ToString();
                return args.Length > 0 ? string.Format(description, args) : description;
            }).Join(",");
        }

        var member = type.GetField(value.ToString());
        var description = member.GetCustomAttributes(typeof(DescriptionAttribute), false) is DescriptionAttribute[] attributes && attributes.Length != 0 ? attributes[0].Description : value.ToString();
        return args.Length > 0 ? string.Format(description, args) : description;
    }

    /// <summary>
    /// 获取枚举值的Description信息
    /// </summary>
    /// <param name ="value">枚举值</param>
    /// <param name ="args">要格式化的对象</param>
    /// <returns>如果未找到DescriptionAttribute则返回null或返回类型描述</returns>
    public static IEnumerable<TAttribute> GetAttributes<TAttribute>(this Enum value) where TAttribute : Attribute
    {
        var type = value.GetType();
        if (!Enum.IsDefined(type, value))
        {
            return Enum.GetValues(type).OfType<Enum>().Where(value.HasFlag).SelectMany(e => type.GetField(e.ToString()).GetCustomAttributes<TAttribute>(false));
        }

        return type.GetField(value.ToString()).GetCustomAttributes<TAttribute>(false);
    }

    /// <summary>
    /// 拆分枚举值
    /// </summary>
    /// <param name ="value">枚举值</param>
    public static IEnumerable<TEnum> Split<TEnum>(this TEnum value) where TEnum : Enum
    {
        var type = typeof(TEnum);
        return Enum.IsDefined(type, value) ? new[]
        {
            value
        } : Enum.GetValues(type).Cast<TEnum>().Where(e => value.HasFlag(e));
    }

    /// <summary>
    /// 获取枚举值的Description信息
    /// </summary>
    /// <param name ="value">枚举值</param>
    /// <returns>如果未找到DescriptionAttribute则返回null或返回类型描述</returns>
    public static EnumDescriptionAttribute GetEnumDescription(this Enum value)
    {
        return GetEnumDescriptions(value).FirstOrDefault();
    }

    /// <summary>
    /// 获取枚举值的Description信息
    /// </summary>
    /// <param name ="value">枚举值</param>
    /// <returns>如果未找到DescriptionAttribute则返回null或返回类型描述</returns>
    public static NullableDictionary<string, (string Description, string Display)> GetTypedEnumDescriptions(this Enum value)
    {
        return GetEnumDescriptions(value).ToDictionarySafety(a => a.Language, a => (a.Description, a.Display));
    }

    /// <summary>
    /// 获取枚举值的Description信息
    /// </summary>
    /// <param name ="value">枚举值</param>
    /// <returns>如果未找到DescriptionAttribute则返回null或返回类型描述</returns>
    public static IEnumerable<EnumDescriptionAttribute> GetEnumDescriptions(this Enum value)
    {
        if (value == null)
        {
            throw new ArgumentNullException(nameof(value));
        }

        var type = value.GetType();
        if (!Enum.IsDefined(type, value))
        {
            return Enum.GetValues(type).OfType<Enum>().Where(value.HasFlag).SelectMany(e => type.GetField(e.ToString()).GetCustomAttributes(typeof(EnumDescriptionAttribute), false).OfType<EnumDescriptionAttribute>());
        }

        return type.GetField(value.ToString()).GetCustomAttributes(typeof(EnumDescriptionAttribute), false).OfType<EnumDescriptionAttribute>();
    }

    /// <summary>
    /// 扩展方法：根据枚举值得到相应的枚举定义字符串
    /// </summary>
    /// <param name="value"></param>
    /// <param name="enumType"></param>
    /// <returns></returns>
    public static String ToEnumString(this int value, Type enumType)
    {
        return GetEnumStringFromEnumValue(enumType)[value.ToString()];
    }

    /// <summary>
    /// 根据枚举类型得到其所有的 值 与 枚举定义字符串 的集合
    /// </summary>
    /// <param name="enumType"></param>
    /// <returns></returns>
    public static NameValueCollection GetEnumStringFromEnumValue(Type enumType)
    {
        var nvc = new NameValueCollection();
        var fields = enumType.GetFields();
        foreach (FieldInfo field in fields)
        {
            if (field.FieldType.IsEnum)
            {
                var strValue = ((int)enumType.InvokeMember(field.Name, BindingFlags.GetField, null, null, null)).ToString();
                nvc.Add(strValue, field.Name);
            }
        }

        return nvc;
    }

    /// <summary>
    /// 根据枚举成员获取自定义属性EnumDisplayNameAttribute的属性DisplayName
    /// </summary>
    public static Dictionary<string, int> GetDescriptionAndValue(this Type enumType) => Enum.GetValues(enumType).Cast<object>().ToDictionary(e => (e as Enum).GetDescription(), e => (int)e);
}