using System;
using NewLife.Reflection;

namespace NewLife.Serialization
{
    /// <summary>定长字符串序列化特性</summary>
    [AttributeUsage(AttributeTargets.Property | AttributeTargets.Field)]
    public class FixedStringAttribute : AccessorAttribute
    {
        /// <summary>长度</summary>
        public Int32 Length { get; set; }

        /// <summary>定长字符串序列化</summary>
        /// <param name="length"></param>
        public FixedStringAttribute(Int32 length) => Length = length;

        /// <summary>从数据流中读取消息</summary>
        /// <param name="formatter">序列化</param>
        /// <param name="context">上下文</param>
        /// <returns>是否成功</returns>
        public override Boolean Read(IFormatterX formatter, AccessorContext context)
        {
            if (formatter is Binary bn)
            {
                var str = bn.ReadFixedString(Length);
                context.Value.SetValue(context.Member, str);

                return true;
            }

            return false;
        }

        /// <summary>把消息写入到数据流中</summary>
        /// <param name="formatter">序列化</param>
        /// <param name="context">上下文</param>
        public override Boolean Write(IFormatterX formatter, AccessorContext context)
        {
            if (formatter is Binary bn)
            {
                var str = context.Value.GetValue(context.Member) as String;
                bn.WriteFixedString(str, Length);

                return true;
            }

            return false;
        }

    }
}