fuelprices/functions.go

package main

import (
	"archive/zip"
	"bytes"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"strconv"

	"github.com/antchfx/xmlquery"
	"gopkg.in/ini.v1"
)

// ParseArgs is not yet implemented
func ParseArgs() error {
	return nil
}

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

	config, err := ini.Load(configfile)
	HandleFatalError(err)

	var fpc FuelPricesConfig

	fuelpricesSection := config.Section("fuelprices")
	fpc.RemoteURL = fuelpricesSection.Key("remote_url").String()
	fpc.RemoteFilename = fuelpricesSection.Key("remote_filename").String()
	fpc.XPathBase = fuelpricesSection.Key("xpath_base").String()
	fpc.Table = fuelpricesSection.Key("table").String()

	influxdbSection := config.Section("influxdb")
	fpc.InfluxHost = influxdbSection.Key("hostname").String()
	fpc.InfluxPort, err = influxdbSection.Key("port").Int()
	HandleError(err)
	fpc.InfluxUser = influxdbSection.Key("username").String()
	fpc.InfluxPass = influxdbSection.Key("password").String()
	HandleError(err)

	fpc.InfluxDB = influxdbSection.Key("database").String()

	fpc.Pos = fuelpricesSection.Key("pos").Strings(",")
	fpc.Types = fuelpricesSection.Key("types").Strings(",")

	*fuelpricesconfig = fpc

	return err
}

// DownloadFile fetch file from webserver
func DownloadFile(url string) error {
	resp, err := http.Get(url)
	HandleError(err)

	szip.Content, err = ioutil.ReadAll(resp.Body)
	HandleError(err)

	err = resp.Body.Close()
	HandleError(err)

	return err
}

// ExtractZip get the XML file to be processed
func ExtractZip() error {

	zipfile, err = zip.NewReader(bytes.NewReader(szip.Content), int64(len(szip.Content)))
	if err != nil {
		log.Fatal("Unable to open zipfile")
	}

	for _, f := range zipfile.File {
		if f.Name == fpc.RemoteFilename {
			rc, err := f.Open()
			if err != nil {
				return err
			}
			ofile.Content, err = ioutil.ReadAll(rc)
			rc.Close()
		} else {
			log.Fatal("File not found")
		}
	}
	return err
}

// GetPrices parses the XML file and get values of prices
func GetPrices(prices **[]Price, spos []string, stypes []string, sxpathbase string) error {

	var pr []Price
	var xml *xmlquery.Node
	f := bytes.NewReader(ofile.Content)
	xml, err = xmlquery.Parse(f)
	HandleError(err)

	for _, station := range spos {
		for _, fuel := range stypes {
			query := fmt.Sprintf(sxpathbase, station, fuel)
			list := xmlquery.FindOne(xml, query)

			for _, i := range list.Attr {
				if i.Name.Local == "valeur" {
					var val float64
					if s, err := strconv.ParseFloat(i.Value, 64); err == nil {
						val = s
					}
					pr = append(pr, Price{ID: station, Fuel: fuel, Amount: val})
				}
			}
		}
	}
	*prices = &pr
	return err
}

// HandleError handles errors to return err
func HandleError(err error) error {
	if err != nil {
		return err
	}
	return nil
}

// HandleFatalError fatal errors
func HandleFatalError(err error) {
	if err != nil {
		log.Fatal(err)
		os.Exit(2)
	}
}

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