using System.Reflection;

namespace YLErp.Helpers
{
    public static class EnumHelper
    {
        /// <summary>
        /// get enum description by name
        /// </summary>
        /// <typeparam name="T">enum type</typeparam>
        /// <param name="enumItemName">the enum name</param>
        /// <returns></returns>
        public static string GetDescriptionByName<TEnum>(TEnum enumItemName)
        {
            var fi = enumItemName.GetType().GetField(enumItemName.ToString());

            if (fi == null)
            {
                return "";
            }

            var attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);

            if (attributes != null && attributes.Length > 0)
            {
                return attributes[0].Description;
            }
            else
            {
                return enumItemName.ToString();
            }
        }

        /// <summary>
        /// 获取枚举类型的键值对
        /// <para>因为目前都是给页面生成代码用,为了使用方便,所以把Value类型改为了string</para>
        /// </summary>
        /// <param name="enumType"></param>
        /// <returns></returns>
        public static Dictionary<string, string> GetDescriptionsByEnum(Type enumType)
        {
            var resultList = new Dictionary<string, string>();
            if (!enumType.IsEnum)
            {
                return resultList;
            }

            var fields = enumType.GetFields(BindingFlags.Static | BindingFlags.Public);
            foreach (var fieldInfo in fields)
            {
                var value = (int)fieldInfo.GetValue(null);
                var description = (DescriptionAttribute[])fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);
                if (description == null || description.Length == 0)
                {
                    resultList[fieldInfo.Name] = value.ToString();
                }
                else
                {
                    resultList[description[0].Description] = value.ToString();
                }
            }

            return resultList;
        }

        public static TEnum GetEnumByDescription<TEnum>(this string description) where TEnum : struct
        {
            var result = default(TEnum);
            if (string.IsNullOrWhiteSpace(description))
            {
                return result;
            }

            var enumType = typeof(TEnum);
            var fields = enumType.GetFields(BindingFlags.Static | BindingFlags.Public);
            foreach (var fieldInfo in fields)
            {
                var des = (DescriptionAttribute[])fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);
                if (des.Length > 0 && des[0].Description == description)
                {
                    result = (TEnum)fieldInfo.GetValue(null);
                }
            }

            return result;
        }

        public static bool TryGetEnumByDescription<TEnum>(string description, out TEnum result) where TEnum : struct
        {
            result = default(TEnum);
            if (string.IsNullOrWhiteSpace(description))
            {
                return false;
            }

            var enumType = typeof(TEnum);
            var fields = enumType.GetFields(BindingFlags.Static | BindingFlags.Public);
            foreach (var fieldInfo in fields)
            {
                var des = (DescriptionAttribute[])fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);
                if (des.Length > 0 && des[0].Description == description)
                {
                    result = (TEnum)fieldInfo.GetValue(null);
                    return true;
                }
            }

            return false;
        }
    }
}