yr/internal/nominatim/nominatim.go

package nominatim

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

type Nominatim struct {
	siteName string
}

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

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

func (n *Nominatim) Search(q string) (*SearchResults, error) {
	url := fmt.Sprintf("https://nominatim.openstreetmap.org/search?q=%s&format=jsonv2", q)

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

	req.Header.Set("User-Agent", n.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
	}

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

	return &result, nil

}

type LookupResult struct {
	Coordinates
	Location string `json:"location"`
}

func (n *Nominatim) Lookup(q string) (*LookupResult, error) {
	r, err := n.Search(q)

	if err != nil {
		return nil, err
	}

	if len(*r) == 0 {
		return nil, fmt.Errorf("no result")
	}

	firstResult := (*r)[0]
	lon, err := strconv.ParseFloat(*firstResult.Longitude, 64)
	if err != nil {
		return nil, err
	}

	lat, err := strconv.ParseFloat(*firstResult.Latitude, 64)
	if err != nil {
		return nil, err
	}

	return &LookupResult{
		Location: *firstResult.Name,
		Coordinates: Coordinates{
			Latitude:  lat,
			Longitude: lon,
		},
	}, nil
}