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

namespace BPASmartClient.IoT.Model
{
    /// <summary>
    /// CRC校验
    /// </summary>
    public class CRC
    {

        #region  CRC16
        public static byte[] CRC16(byte[] data)
        {
            int len = data.Length;
            if (len > 0)
            {
                ushort crc = 0xFFFF;

                for (int i = 0; i < len; i++)
                {
                    crc = (ushort)(crc ^ (data[i]));
                    for (int j = 0; j < 8; j++)
                    {
                        crc = (crc & 1) != 0 ? (ushort)((crc >> 1) ^ 0xA001) : (ushort)(crc >> 1);
                    }
                }
                byte hi = (byte)((crc & 0xFF00) >> 8);  //高位置
                byte lo = (byte)(crc & 0x00FF);         //低位置

                return new byte[] { hi, lo };
            }
            return new byte[] { 0, 0 };
        }

        public static byte[] CRC16_L(byte[] data)
        {
            int len = data.Length;
            if (len > 0)
            {
                ushort crc = 0xFFFF;

                for (int i = 0; i < len; i++)
                {
                    crc = (ushort)(crc ^ (data[i]));
                    for (int j = 0; j < 8; j++)
                    {
                        crc = (crc & 1) != 0 ? (ushort)((crc >> 1) ^ 0xA001) : (ushort)(crc >> 1);
                    }
                }
                byte hi = (byte)((crc & 0xFF00) >> 8);  //高位置
                byte lo = (byte)(crc & 0x00FF);         //低位置

                return new byte[] { lo,hi };
            }
            return new byte[] { 0, 0 };
        }
        #endregion

        #region  ToCRC16
        public static string ToCRC16(string content)
        {
            return ToCRC16(content, Encoding.UTF8);
        }

        public static string ToCRC16(string content, bool isReverse)
        {
            return ToCRC16(content, Encoding.UTF8, isReverse);
        }

        public static string ToCRC16(string content, Encoding encoding)
        {
            return ByteToString(CRC16(encoding.GetBytes(content)), true);
        }

        public static string ToCRC16(string content, Encoding encoding, bool isReverse)
        {
            return ByteToString(CRC16(encoding.GetBytes(content)), isReverse);
        }

        public static string ToCRC16(byte[] data)
        {
            return ByteToString(CRC16(data), true);
        }

        public static string ToCRC16(byte[] data, bool isReverse)
        {
            return ByteToString(CRC16(data), isReverse);
        }
        #endregion

        #region  ToModbusCRC16
        public static string ToModbusCRC16(string s)
        {
            return ToModbusCRC16(s, true);
        }

        public static string ToModbusCRC16(string s, bool isReverse)
        {
            return ByteToString(CRC16(StringToHexByte(s)), isReverse);
        }

        public static string ToModbusCRC16(byte[] data)
        {
            return ToModbusCRC16(data, true);
        }

        public static string ToModbusCRC16(byte[] data, bool isReverse)
        {
            return ByteToString(CRC16(data), isReverse);
        }
        #endregion

        #region  ByteToString
        public static string ByteToString(byte[] arr, bool isReverse)
        {
            try
            {
                byte hi = arr[0], lo = arr[1];
                return Convert.ToString(isReverse ? hi + lo * 0x100 : hi * 0x100 + lo, 16).ToUpper().PadLeft(4, '0');
            }
            catch (Exception ex) { throw (ex); }
        }

        public static string ByteToString(byte[] arr)
        {
            try
            {
                return ByteToString(arr, true);
            }
            catch (Exception ex) { throw (ex); }
        }
        #endregion

        #region  StringToHexString
        public static string StringToHexString(string str)
        {
            StringBuilder s = new StringBuilder();
            foreach (short c in str.ToCharArray())
            {
                s.Append(c.ToString("X4"));
            }
            return s.ToString();
        }
        #endregion

        #region  StringToHexByte
        private static string ConvertChinese(string str)
        {
            StringBuilder s = new StringBuilder();
            foreach (short c in str.ToCharArray())
            {
                if (c <= 0 || c >= 127)
                {
                    s.Append(c.ToString("X4"));
                }
                else
                {
                    s.Append((char)c);
                }
            }
            return s.ToString();
        }

        private static string FilterChinese(string str)
        {
            StringBuilder s = new StringBuilder();
            foreach (short c in str.ToCharArray())
            {
                if (c > 0 && c < 127)
                {
                    s.Append((char)c);
                }
            }
            return s.ToString();
        }

        /// <summary>
        /// 字符串转16进制字符数组
        /// </summary>
        /// <param name="hex"></param>
        /// <returns></returns>
        public static byte[] StringToHexByte(string str)
        {
            return StringToHexByte(str, false);
        }

        /// <summary>
        /// 字符串转16进制字符数组
        /// </summary>
        /// <param name="str"></param>
        /// <param name="isFilterChinese">是否过滤掉中文字符</param>
        /// <returns></returns>
        public static byte[] StringToHexByte(string str, bool isFilterChinese)
        {
            string hex = isFilterChinese ? FilterChinese(str) : ConvertChinese(str);

            //清除所有空格
            hex = hex.Replace(" ", "");
            //若字符个数为奇数，补一个0
            hex += hex.Length % 2 != 0 ? "0" : "";

            byte[] result = new byte[hex.Length / 2];
            for (int i = 0, c = result.Length; i < c; i++)
            {
                result[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
            }
            return result;
        }
        #endregion

    }

    class CRC16Standard
    {
        private static int[] table = { 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, 0xC601, 0x06C0, 0x0780, 0xC741,
        0x0500, 0xC5C1, 0xC481, 0x0440, 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, 0x0A00, 0xCAC1, 0xCB81, 0x0B40,
        0xC901, 0x09C0, 0x0880, 0xC841, 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, 0x1E00, 0xDEC1, 0xDF81, 0x1F40,
        0xDD01, 0x1DC0, 0x1C80, 0xDC41, 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, 0xD201, 0x12C0, 0x1380, 0xD341,
        0x1100, 0xD1C1, 0xD081, 0x1040, 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240, 0x3600, 0xF6C1, 0xF781, 0x3740,
        0xF501, 0x35C0, 0x3480, 0xF441, 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, 0xFA01, 0x3AC0, 0x3B80, 0xFB41,
        0x3900, 0xF9C1, 0xF881, 0x3840, 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, 0xEE01, 0x2EC0, 0x2F80, 0xEF41,
        0x2D00, 0xEDC1, 0xEC81, 0x2C40, 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, 0x2200, 0xE2C1, 0xE381, 0x2340,
        0xE101, 0x21C0, 0x2080, 0xE041, 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240, 0x6600, 0xA6C1, 0xA781, 0x6740,
        0xA501, 0x65C0, 0x6480, 0xA441, 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, 0xAA01, 0x6AC0, 0x6B80, 0xAB41,
        0x6900, 0xA9C1, 0xA881, 0x6840, 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, 0xBE01, 0x7EC0, 0x7F80, 0xBF41,
        0x7D00, 0xBDC1, 0xBC81, 0x7C40, 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640, 0x7200, 0xB2C1, 0xB381, 0x7340,
        0xB101, 0x71C0, 0x7080, 0xB041, 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241, 0x9601, 0x56C0, 0x5780, 0x9741,
        0x5500, 0x95C1, 0x9481, 0x5440, 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40, 0x5A00, 0x9AC1, 0x9B81, 0x5B40,
        0x9901, 0x59C0, 0x5880, 0x9841, 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, 0x4E00, 0x8EC1, 0x8F81, 0x4F40,
        0x8D01, 0x4DC0, 0x4C80, 0x8C41, 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, 0x8201, 0x42C0, 0x4380, 0x8341,
        0x4100, 0x81C1, 0x8081, 0x4040, };

        public static byte[] getCRCBytes(byte[] data)
        {
            int crc = 0x0000;
            foreach (byte b in data)
            {
                crc = (crc >> 8) ^ table[(crc ^ b) & 0xff];
            }
            return new byte[] { (byte)(0xff & crc), (byte)((0xff00 & crc) >> 8) };
        }
    }
}