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

namespace Tps_LQ_Transmitter.com
{
    public class MySerial
    {
        SerialPort serial;
        public bool IsOpen
        {
            get
            {
                if (serial == null)
                    return false;

                return serial.IsOpen;
            }
        }

        public MySerial()
        {

        }
        public virtual void portClose()
        {         
        }
        public bool Init(string com)
        {
            serial = new SerialPort();
            serial.PortName = com;     //端口号设置为com_port的值
            serial.BaudRate = 9600;
            serial.DataBits = 8;
            serial.StopBits = StopBits.One;//停止位设置为com_stop的值
            serial.Parity = Parity.None;//获取奇偶校验选项的值
            serial.ReadTimeout = 1000;    //读取等待时间1000
                                          // serial.ReceivedBytesThreshold = 1;
                                          // serial.DataReceived += Serial_DataReceived;
            serial.Open();
            return serial.IsOpen;
        }
        /// <summary>
        /// 串口COM先写后读方法；
        /// 写入的时候会自动在后面添加modbus-CRC16检验
        /// </summary>
        /// <param name="data">写入的数据</param>
        /// <returns>返回的数据</returns>
        public virtual byte[] writeAndRead(byte[] data)
        {
            if (data == null)
                return null;

            //先读空
            if (serial.BytesToRead > 0)
                serial.DiscardInBuffer();

            byte[] crc = crc16(data);
            byte[] newarray = new byte[data.Length + 2];
            Array.Copy(data, newarray, data.Length);
            newarray[data.Length] = crc[0];
            newarray[data.Length + 1] = crc[1];

            serial.Write(newarray, 0, newarray.Length);
            Thread.Sleep(150);
            if(serial.BytesToRead > 0)
            {
                byte[] dat = new byte[serial.BytesToRead];
                serial.Read(dat, 0, dat.Length);
                return dat;
            }
            else
            {
                return null;
            }        
        }
        /// <summary>
        /// modbus_CRC16校验
        /// </summary>
        /// <param name="data">需要校验的byte[]型数据</param>
        /// <returns>校验后数据(高位在后，低位在前)</returns>
        public byte[] crc16(byte[] data)
        {
            byte[] crc = new byte[2];

            UInt16 wCrc = 0xFFFF;
            for (int i = 0; i < data.Length; i++)
            {
                wCrc ^= Convert.ToUInt16(data[i]);
                for (int j = 0; j < 8; j++)
                {
                    if ((wCrc & 0x0001)==1)
                    {
                        wCrc >>= 1;
                        wCrc ^= 0xA001;//异或多项式
                    }
                    else
                    {
                        wCrc >>= 1;
                    }
                }
            }
            crc[1] = (byte)((wCrc & 0xFF00) >> 8);//高位在后
            crc[0] = (byte)(wCrc & 0x00FF);       //低位在前

            return crc;
        }

        private void Serial_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            
        }
    }
}