package utils

import (
	"io"
	"time"

	"github.com/tarm/serial"
	"go.uber.org/zap"
)

var (
	device     string
	baudrate   int
	bytesize   byte
	stopbits   byte
	port       *serial.Port
	portOpened = false
	Log        *zap.SugaredLogger
)

const readDuration = 500 * time.Millisecond

// OpenPort open serial port
func OpenPort(device string, baudrate int, bytesize byte, stopbits byte) error {
	Log.Infow("opening serial device ",
		"port", device,
		"baudrate", baudrate,
		"bytesize", bytesize,
		"stopbits", stopbits)
	config := &serial.Config{Name: device,
		Baud:        baudrate,
		Size:        bytesize,
		StopBits:    serial.StopBits(stopbits),
		ReadTimeout: readDuration}
	var err error
	port, err = serial.OpenPort(config)
	if err != nil {
		Log.Fatal("error in open serial port ", err)
		return err
	}
	Log.Infof("%s  opened", device)
	portOpened = true
	return nil
}

//ReadPort read byte array from port
func ReadPort() ([]byte, int) {
	buffer := make([]byte, 256)
	if !ServerRunning {
		return buffer, 0
	}
	count, err := port.Read(buffer)
	if err != nil && err != io.EOF {
		Log.Error("error in read port ", err)
		//TODO: 3 time fail try to
	}
	return buffer, count
}

//IsPortOpen check serial port status
func IsPortOpen() bool {
	return portOpened
}