weather/functions.go

package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"time"

	client "github.com/influxdata/influxdb1-client/v2"
	"gopkg.in/ini.v1"
)

// GetConfig fetch config from ini file
func GetConfig(configfile string, weatherconfig *WeatherConfig) error {
	flag.Usage = Usage

	config, err := ini.Load(configfile)
	if err != nil {
		return err
	}

	var wc WeatherConfig

	weatherSection := config.Section("weather")
	wc.WeatherVersion = weatherSection.Key("version").String()
	wc.WeatherAppID = weatherSection.Key("appid").String()
	wc.WeatherCities = weatherSection.Key("cities").Strings(",")
	wc.WeatherMeasurements = weatherSection.Key("measurements").Strings(",")
	wc.WeatherTable = weatherSection.Key("table").String()

	influxdbSection := config.Section("influxdb")
	wc.InfluxHost = influxdbSection.Key("hostname").String()
	wc.InfluxPort, err = influxdbSection.Key("port").Int()
	if err != nil {
		return err
	}
	wc.InfluxUser = influxdbSection.Key("username").String()
	wc.InfluxPass = influxdbSection.Key("password").String()
	wc.InfluxDB = influxdbSection.Key("database").String()

	*weatherconfig = wc

	return err
}

func FetchData(city string) (Data, error) {
	var d Data

	pollTo := 30 * time.Millisecond

	c := &http.Client{Timeout: pollTo * time.Second, Transport: &http.Transport{
		IdleConnTimeout:    pollTo,
		DisableCompression: false,
	}}

	resp, err := c.Get(fmt.Sprintf("https://api.openweathermap.org/data/%s/weather?q=%s&appid=%s", wc.WeatherVersion, city, wc.WeatherAppID))

	b, err := ioutil.ReadAll(resp.Body)
	err = json.Unmarshal(b, &d)

	d.Humidity = d.Main["humidity"]
	d.Temperature = kelvin + d.Main["temp"]

	return d, err
}

// SendToInflux sends time series data to influxdb
func SendToInflux(wc *WeatherConfig, city string, measurement string, value float64) error {

	httpClient, err := client.NewHTTPClient(client.HTTPConfig{
		Addr:     fmt.Sprintf("http://%s:%d", wc.InfluxHost, wc.InfluxPort),
		Username: wc.InfluxUser,
		Password: wc.InfluxPass,
	})
	if err != nil {
		return err
	}

	bp, err := client.NewBatchPoints(client.BatchPointsConfig{
		Database: wc.InfluxDB,
	})
	if err != nil {
		return err
	}

	tags := map[string]string{"city": city}
	fields := map[string]interface{}{"value": value}

	point, _ := client.NewPoint(
		measurement,
		tags,
		fields,
		time.Now(),
	)

	bp.AddPoint(point)
	err = httpClient.Write(bp)
	if err != nil {
		return err
	}

	return nil
}

// Usage displays possible arguments
func Usage() {
	flag.PrintDefaults()
	os.Exit(1)
}