package util

import (
	"bytes"
	"encoding/hex"
	"fmt"
	"time"

	"github.com/tarm/serial"
)

// ReadSerial read from serial
func ReadSerial(name string, baudrate int, bits byte) (data []byte, err error) {
	s := &serial.Port{}
	c := &serial.Config{}
	c.Name = name
	c.Baud = baudrate
	c.Size = bits
	c.StopBits = serial.Stop1
	c.ReadTimeout = 100 * time.Microsecond
	c.Parity = serial.ParityNone

	s, err = serial.OpenPort(c)
	if err != nil {
		return
	}
	defer s.Close()

	var ss bytes.Buffer
	buf := make([]byte, 1024)
	for {
		n, err := s.Read(buf)
		if err != nil {
			if ss.Len() > 0 {
				break
			}
			continue
		}
		if n > 0 {
			if n == 1 {
				if buf[0] == 0x0d {
					continue
				}
				if buf[0] == 0x0a {
					break
				}
			} else if n == 2 {
				if buf[0] == 0x0d && buf[1] == 0x0a {
					break
				}
			}
			ss.Write(buf[:n])
			fmt.Println("Read", n, "bytes", string(buf[:n]), hex.EncodeToString(buf[:n]))
		} else {
			break
		}
	}

	if ss.Len() > 0 {
		data = ss.Bytes()
	}
	return
}