PKGBUILD/pkg/sensor/ds18b20.go

package sensor

import (
	"context"
	"fmt"
	"io/ioutil"
	"math"
	"path/filepath"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/go-flucky/flucky/pkg/types"
	uuid "github.com/satori/go.uuid"
)

// DS18B20 is a sensor to measure humidity and temperature.
type DS18B20 struct {
	*types.Sensor
}

// GetSensorModel returns the sensor model
func (s *DS18B20) GetSensorModel() types.SensorModel {
	return s.Sensor.SensorModel
}

// GetSensor return the sensor struct
func (s *DS18B20) GetSensor() *types.Sensor {
	return s.Sensor
}

// ReadTemperature measure the temperature
func (s *DS18B20) ReadTemperature(degree types.Degree, round float64) (*types.Temperature, error) {

	data, err := ioutil.ReadFile(filepath.Join("/sys/bus/w1/devices", *s.WireID, "/w1_slave"))
	if err != nil {
		return nil, fmt.Errorf("Can not read data from sensor %v", s.SensorName)
	}

	raw := string(data)

	i := strings.LastIndex(raw, "t=")
	if i == -1 {
		return nil, ErrReadSensor
	}

	c, err := strconv.ParseFloat(raw[i+2:len(raw)-1], 64)
	if err != nil {
		return nil, ErrParseData
	}

	temperatureValue := c / 1000

	// Convert temperature degree
	temperatureValue = convertTemperatureMeasurementUnit(temperatureValue, types.DegreeCelsius, degree)

	// round
	if round != 0 {
		temperatureValue = math.Round(temperatureValue/round) * round
	}

	temperature := &types.Temperature{
		TemperatureID:       uuid.NewV4().String(),
		TemperatureValue:    temperatureValue,
		TemperatureDegree:   degree,
		TemperatureFromDate: time.Now(),
		TemperatureTillDate: time.Now(),
		SensorID:            s.SensorID,
	}

	return temperature, nil

}

// ReadTemperatureWriteIntoChannel and write values into a channel
func (s *DS18B20) ReadTemperatureWriteIntoChannel(degree types.Degree, round float64, temperatureChannel chan<- *types.Temperature, errorChannel chan<- error, wg *sync.WaitGroup) {
	if wg != nil {
		defer wg.Done()
	}

	temperature, err := s.ReadTemperature(degree, round)
	if err != nil {
		errorChannel <- err
		return
	}
	temperatureChannel <- temperature
}

// ReadTemperatureContinously into a channel until context closed
func (s *DS18B20) ReadTemperatureContinously(ctx context.Context, degree types.Degree, round float64, temperatureChannel chan<- *types.Temperature, errorChannel chan<- error) {
	for {
		select {
		case <-ctx.Done():
			errorChannel <- fmt.Errorf("%v: Context closed: %v", s.SensorName, ctx.Err())
			return
		default:
			s.ReadTemperatureWriteIntoChannel(degree, round, temperatureChannel, errorChannel, nil)
		}
	}
}