Sample code for URL signing to query Google Maps API

urlsigner.go

// See: https://developers.google.com/maps/documentation/static-maps/get-api-key
//
// WARNING: Unfinised work...

package main

// const (
// 	gmapsHost = "https://maps.googleapis.com"
// 	gmapsURL  = "/maps/api/geocode/json"
// )

type Geocoder struct {
	clientID string
	apiKey   string
	Channel  string
}

func NewGeocoder(id string, key string) Geocoder {
	return Geocoder{clientID: id, apiKey: key}
}

func (Geocoder) SendQuery(clientID string, apiKey string, address string) (err error) {
	c, err := maps.NewClient(maps.ClID WithAPIKey("Insert-API-Key-Here"))
}

func (coder Geocoder) encodeURL(address string) string {
	u, err := url.Parse(gmapsHost)
	if err != nil {
		panic("url module cannot parse https://maps.googleapis.com")
	}
	u.Path += gmapsURL
	params := url.Values{}
	params.Add("address", address)
	params.Add("client", coder.clientID)
	params.Add("channel", coder.channel)

	u.RawQuery = params.Encode()

	return u.Path + "?" + u.RawQuery
}

// str: u.Path + "?" + u.RawQuery
func (coder Geocoder) signURL(u string) (sig string) {
	key, err := base64.URLEncoding.DecodeString(coder.apiKey)
	if err != nil {
		panic("base64 module cannot encode API key")
	}

	h := hmac.New(sha1.New, key)
	h.Write([]byte(u))
	sig = base64.URLEncoding.EncodeToString(h.Sum(nil))
	return sig
}

func queryURL(u *url.URL, sig string) {
	params := u.Query()
	params.Add("signature", sig)

	u.RawQuery += "&signature=" + sig
}

func (coder Geocoder) Request(address string) {
	u := coder.encodeURL(address)
	fmt.Printf("url: %s\n", u)
	sig := coder.signURL(u)
	fmt.Printf("sig: %s\n", sig)
	urlStr := gmapsHost + u + "&signature=" + sig
	fmt.Println(urlStr)
	client, _ := maps.NewClient(
		maps.WithClientIDAndSignature(coder.clientID, coder.apiKey),
		// maps.WithClientIDAndSignature(coder.clientID, sig),
		maps.WithChannel(coder.channel),
	)
	r := &maps.GeocodingRequest{
		Address: address,
	}
	resp, err := client.Geocode(context.Background(), r)
	if err != nil {
		log.Fatalln(err)
	}
	pretty.Println(resp[0].Geometry.Location.Lat)
	pretty.Println(resp[0].Geometry.Location.Lng)
	// pretty.Println(resp)
	// if err != nil {
	// 	log.Fatalf("fatal error: %s", err)
	// }
	// r := &maps.DirectionsRequest{
	// 	Origin:      "Sydney",
	// 	Destination: "Perth",
	// }
	// route, _, err := c.Directions(context.Background(), r)
	// if err != nil {
	// 	log.Fatalf("fatal error: %s", err)
	// }

	// pretty.Println(route)
}