using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace MECF.Framework.RT.Core.IoProviders.Siemens.IMessage
{
    /// <summary>
    /// 西门子Fetch/Write消息解析协议
    /// </summary>
    public class FetchWriteMessage : INetMessage
    {
        /// <summary>
        /// 消息头的指令长度
        /// </summary>
        public int ProtocolHeadBytesLength
        {
            get
            {
                return 16;
            }
        }


        /// <summary>
        /// 从当前的头子节文件中提取出接下来需要接收的数据长度
        /// </summary>
        /// <returns>返回接下来的数据内容长度</returns>
        public int GetContentLengthByHeadBytes( )
        {
            if (SendBytes != null)
            {
                if (HeadBytes[5] == 0x04)
                {
                    return 0;
                }
                else
                {
                    return SendBytes[12] * 256 + SendBytes[13];
                }
            }
            else
            {
                return 16;
            }
        }


        /// <summary>
        /// 检查头子节的合法性
        /// </summary>
        /// <param name="token">特殊的令牌，有些特殊消息的验证</param>
        /// <returns>是否合法</returns>
        public bool CheckHeadBytesLegal( byte[] token )
        {
            if (HeadBytes == null) return false;

            if (HeadBytes[0] == 0x53 && HeadBytes[1] == 0x35)
            {
                return true;
            }
            else
            {
                return false;
            }
        }


        /// <summary>
        /// 获取头子节里的消息标识
        /// </summary>
        /// <returns>消息标识</returns>
        public int GetHeadBytesIdentity( )
        {
            return HeadBytes[3];
        }


        /// <summary>
        /// 消息头字节
        /// </summary>
        public byte[] HeadBytes { get; set; }


        /// <summary>
        /// 消息内容字节
        /// </summary>
        public byte[] ContentBytes { get; set; }

        /// <summary>
        /// 发送的字节信息
        /// </summary>
        public byte[] SendBytes { get; set; }
    }
}
