country-geo-locations/cfg/cfg.go

package cfg

import (
	"fmt"

	"github.com/alecthomas/kong"
)

type AppSettings struct {
	ServerAddress string `name:"listen-address" env:"GEOIP_LISTEN_ADDRESS" help:"Address to use for the metrics server" default:"${default_address}"`
	DataFile      string `name:"data-file" env:"GEOIP_DATA_FILE" help:"path to data file" default:"${default_file_path}"`
	DataURL       string `name:"data-url" env:"GEOIP_DATA_URL" help:"url to data file"`
}

func NewAppSettings() *AppSettings {
	return &AppSettings{}
}

func (s *AppSettings) Parse() error {
	ctx := kong.Parse(
		s,
		kong.Vars{
			"default_address":   ":8080",
			"default_file_path": "./data.csv",
		},
		kong.Name("country_geo_locations"),
		kong.Description("🚀 Start a simple web server for GeoIP data"),
		kong.UsageOnError(),
	)

	err := validateFlags(*s)
	if err != nil {
		ctx.PrintUsage(false)
		fmt.Println()
		return err
	}
	return nil
}

func validateFlags(settings AppSettings) error {
	if settings.DataURL == "" {
		return fmt.Errorf("error: invalid data url, must not be blank")
	}
	return nil
}