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

namespace TZONE.GPSSocketServer.Common
{
    /// <summary>
    /// CRC校验类
    /// </summary>
    public class CRC
    {
        /// <summary>
        /// CRC长度
        /// </summary>
        private const int CRC_LEN = 2;

        /// <summary>
        /// Table of CRC values for high-order byte
        /// CRC高位字节表
        /// </summary>
        private readonly byte[] _auchCRCHi = new byte[]
        {
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 
            0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 
            0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 
            0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 
            0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 
            0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 
            0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 
            0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 
            0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 
            0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 
            0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 
            0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 
            0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40
        };

        /// <summary>
        /// Table of CRC values for low-order byte
        /// CRC低位字节表
        /// </summary>
        private readonly byte[] _auchCRCLo = new byte[]
        {
            0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 
            0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD, 
            0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09, 
            0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A, 
            0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4, 
            0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3, 
            0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 
            0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4, 
            0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A, 
            0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29, 
            0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED, 
            0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26, 
            0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 
            0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67, 
            0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F, 
            0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 
            0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 
            0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5, 
            0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 
            0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92, 
            0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C, 
            0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 
            0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B, 
            0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C, 
            0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 
            0x43, 0x83, 0x41, 0x81, 0x80, 0x40
        };

        /// <summary>
        /// CRC16位计算检验
        /// </summary>
        /// <param name="buffer">校验byte数组</param>
        /// <returns>返回的是一个ushort类型的值</returns>
        public ushort CalculateCrc16(byte[] buffer)
        {
            string str = ToHexString(buffer);
            str = str.Replace(" ", "");
            //HexCon.StringToByte(str);
            byte[] b = System.Text.Encoding.ASCII.GetBytes(str);
            byte crcHi = 0xff;  // high crc byte initialized
            byte crcLo = 0xff;  // low crc byte initialized 
            for (int i = 0; i < b.Length; i++)
            {
                int crcIndex = crcLo ^ b[i]; // calculate the crc lookup index
                crcLo = (byte)(crcHi ^ _auchCRCHi[crcIndex]);
                crcHi = _auchCRCLo[crcIndex];
            }
            return (ushort)(crcHi << 8 | crcLo);
        }


        /// <summary>
        /// CRC16位计算检验
        /// CalculateCrc16返回的是一个ushort类型的值，如果要返回Crc高字节和低字节，可重写CalculateCrc16函数
        /// </summary>
        /// <param name="buffer">校验byte数组</param>
        /// <param name="crcHi">输出高位</param>
        /// <param name="crcLo">输出低位</param>
        /// <returns>返回的是一个ushort类型的值</returns>
        public ushort CalculateCrc16(byte[] buffer, out byte crcHi, out byte crcLo)
        {
            crcHi = 0xff;  // high crc byte initialized
            crcLo = 0xff;  // low crc byte initialized 
            for (int i = 0; i < buffer.Length; i++)
            {
                int crcIndex = crcHi ^ buffer[i]; // calculate the crc lookup index
                crcHi = (byte)(crcLo ^ _auchCRCHi[crcIndex]);
                crcLo = _auchCRCLo[crcIndex];
            }
            return (ushort)(crcHi << 8 | crcLo);
        }

        /// <summary>
        /// CRC16位 Hex检验
        /// </summary>
        /// <param name="buffer">校验byte数组</param>
        /// <returns>返回的是一个ushort类型的值</returns>
        public ushort CalculateCrc16Hex(byte[] buffer)
        {
            byte crcHi = 0xff;  // high crc byte initialized
            byte crcLo = 0xff;  // low crc byte initialized 
            for (int i = 0; i < buffer.Length; i++)
            {
                int crcIndex = crcHi ^ buffer[i]; // calculate the crc lookup index
                crcHi = (byte)(crcLo ^ _auchCRCHi[crcIndex]);
                crcLo = _auchCRCLo[crcIndex];
            }
            return (ushort)(crcHi | crcLo << 8);
        }

        /// <summary>
        /// byte数组转换成2位十六进制
        /// </summary>
        /// <param name="bytes">传入byte数组</param>
        /// <returns>返回一个字符串</returns>
        public static string ToHexString(byte[] bytes) // 0xae00cf => "AE00CF "
        {
            string hexString = string.Empty;
            if (bytes != null)
            {
                StringBuilder strB = new StringBuilder();

                for (int i = 0; i < bytes.Length; i++)
                {
                    strB.Append(bytes[i].ToString("X2"));
                }
                hexString = strB.ToString();
            }
            return hexString;
        }
        /// <summary>
        /// 字符串转16进制字节数组
        /// </summary>
        /// <param name="hexString">转换字符</param>
        /// <returns>返回转换后字符数组</returns>
        public static byte[] GetStringToToHexByte(string hexString)
        {
            hexString = hexString.Replace(" ", "");
            if ((hexString.Length % 2) != 0)
                hexString += " ";
            byte[] returnBytes = new byte[hexString.Length / 2];
            for (int i = 0; i < returnBytes.Length; i++)
                returnBytes[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16);
            return returnBytes;
        }
        /// <summary>
        /// 获取校验CRC码
        /// </summary>
        /// <param name="obj">校验字符</param>
        /// <returns></returns>
        public static string GetCRC(string obj)
        {
            byte[] b =GetStringToToHexByte(obj);
            Common.CRC crc = new Common.CRC();
            ushort crc16byte = crc.CalculateCrc16Hex(b);
            byte[] b1 = new byte[2];
            b1[0] = (byte)((0xff00 & crc16byte) >> 8);
            b1[1] = (byte)(0xff & crc16byte);
            string H1 =ToHexString(b1);
            byte[] H2 = Encoding.UTF8.GetBytes(H1);
            string ATH =ToHexString(H2);
            return ATH;
        }

    }
}
