using System.Collections.Concurrent;
using System.ComponentModel;
using System.Reflection;

namespace DS.Module.Core;

/// <summary>
/// 枚举工具类
/// </summary>
public static class EnumUtil
{
    // 枚举显示字典缓存
    private static readonly ConcurrentDictionary<Type, Dictionary<string, string>> EnumShowNameDict = new ConcurrentDictionary<Type, Dictionary<string, string>>();

    /// <summary>
    /// 字符串转Enum
    /// </summary>
    /// <typeparam name="T">枚举</typeparam>
    /// <param name="str">字符串</param>
    /// <returns>转换的枚举</returns>
    public static T ToEnum<T>(this string str)
    {
        try
        {
            return (T)Enum.Parse(typeof(T), str);
        }
        catch
        {
            return default(T);
        }
    }

    /// <summary>
    /// 获取到对应枚举的描述-没有描述信息，返回枚举值
    /// </summary>
    /// <param name="enum"></param>
    /// <returns></returns>
    public static string EnumDescription(this Enum @enum)
    {
        Type type = @enum.GetType();
        string name = Enum.GetName(type, @enum);
        if (name == null)
        {
            return null;
        }
        FieldInfo field = type.GetField(name);
        if (!(Attribute.GetCustomAttribute(field, typeof(DescriptionAttribute)) is DescriptionAttribute attribute))
        {
            return name;
        }
        return attribute?.Description;
    }

    public static int ToEnumInt(this Enum e)
    {
        try
        {
            return e.GetHashCode();
        }
        catch (Exception)
        {
            return 0;
        }
    }


    /// <summary>
    /// 获取枚举对象Key与名称的字典（缓存）
    /// </summary>
    /// <param name="enumType"></param>
    /// <returns></returns>
    public static Dictionary<string, string> GetEnumDictionaryWithKey(this Type enumType)
    {
        if (!enumType.IsEnum)
            throw new ArgumentException("Type '" + enumType.Name + "' is not an enum.");

        // 查询缓存
        var enumDic = EnumShowNameDict.ContainsKey(enumType) ? EnumShowNameDict[enumType] : new Dictionary<string, string>();
        if (enumDic.Count != 0)
            return enumDic;

        string[] fieldstrs = Enum.GetNames(enumType);
        // 取枚举类型的Key/Value字典集合
        enumDic = fieldstrs.Select(item =>
        {
            object[] arr = enumType.GetField(item).GetCustomAttributes(typeof(DescriptionAttribute), true);

            return new
            {
                Key = item,
                Val = ((DescriptionAttribute)arr[0]).Description
            };
        }).ToDictionary(a => a.Key, b => b.Val);

        // 缓存
        EnumShowNameDict[enumType] = enumDic;

        return enumDic;
    }
}