yr/internal/met/met.go

package met

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

type Met struct {
	siteName string
}

func New(siteName string) (*Met, error) {
	if siteName == "" {
		return nil, fmt.Errorf("`siteName` must be defined.")
	}

	return &Met{
		siteName: siteName,
	}, nil
}

func (m *Met) Forecast(lat, lon float64, alt *int) (*LocationForecastResult, error) {
	url := fmt.Sprintf("https://api.met.no/weatherapi/locationforecast/2.0/complete?lat=%.4f&lon=%.4f&altitude=%d", lat, lon, alt)

	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		return nil, err
	}

	req.Header.Set("User-Agent", m.siteName)
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("%s", resp.Status)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}

	forecast := LocationForecastResult{}
	err = json.Unmarshal(body, &forecast)
	if err != nil {
		return nil, err
	}

	return &forecast, nil
}