using IdentityServer4.Models;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace BZPT.DTO
{
    [AttributeUsage(AttributeTargets.Property)]
    public class MaxByteLengthAttribute : ValidationAttribute
    {
        private readonly Encoding _encoding = Encoding.UTF8;
        private readonly int _maxBytes;

        public MaxByteLengthAttribute(int maxBytes)
        {
            _maxBytes = maxBytes;
        }

        protected override ValidationResult IsValid(object value, ValidationContext context)
        {
            if (value is string str && _encoding.GetByteCount(str) > _maxBytes)
            {
                return new ValidationResult(ErrorMessage ?? $"字节长度超过 {_maxBytes}");
            }
            return ValidationResult.Success;
        }
    }
}