Add proxied autocomplete for Stadia

This allows me to make the format consistent and to cache the
intermediate results, which is useful for speed and testing

stadia/geocode_autocomplete.go

@@ -0,0 +1,72 @@
+package stadia
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/google/go-querystring/query"
+)
+
+type RequestGeocodeAutocomplete struct {
+	Text string `url:"text" json:"text"`
+
+	// Boundary circle parameters
+	BoundaryCircleLat    *float64 `url:"boundary.circle.lat,omitempty"`
+	BoundaryCircleLon    *float64 `url:"boundary.circle.lon,omitempty"`
+	BoundaryCircleRadius *float64 `url:"boundary.circle.radius,omitempty"`
+
+	BoundaryCountry *string `url:"boundary.country,omitempty"` //comma-delimited ISO 2 or 3 character code
+	BoundaryGID     *string `url:"boundary.gid,omitempty"`     // The GID of a region to limit the search to
+
+	// Boundary parameters
+	BoundaryRectMaxLat *float64 `url:"boundary.rect.max_lat,omitempty"`
+	BoundaryRectMinLat *float64 `url:"boundary.rect.min_lat,omitempty"`
+	BoundaryRectMaxLon *float64 `url:"boundary.rect.max_lon,omitempty"`
+	BoundaryRectMinLon *float64 `url:"boundary.rect.min_lon,omitempty"`
+
+	// Focus point
+	FocusPointLat *float64 `url:"focus.point.lat,omitempty" json:",omitempty"`
+	FocusPointLng *float64 `url:"focus.point.lon,omitempty" json:",omitempty"`
+
+	// Other parameters
+	Lang    *string  `url:"lang,omitempty" json:"lang,omitempty"`
+	Layers  []string `url:"layers,omitempty,comma" json:"layers,omitempty"`
+	Size    *int     `url:"size,omitempty" json:"size,omitempty"`
+	Sources []string `url:"sources,omitempty,comma" json:"sources,omitempty"`
+}
+
+func (r *RequestGeocodeAutocomplete) SetBoundaryRect(xmin, ymin, xmax, ymax float64) {
+	r.BoundaryRectMaxLat = &ymax
+	r.BoundaryRectMinLat = &ymin
+	r.BoundaryRectMaxLon = &xmax
+	r.BoundaryRectMinLon = &xmin
+}
+func (r *RequestGeocodeAutocomplete) SetFocusPoint(x, y float64) {
+	r.FocusPointLat = &y
+	r.FocusPointLng = &x
+}
+func (s *StadiaMaps) GeocodeAutocomplete(ctx context.Context, req RequestGeocodeAutocomplete) (*GeocodeResponse, error) {
+	// https://docs.stadiamaps.com/geocoding-search-autocomplete/search/
+	var result GeocodeResponse
+
+	query, err := query.Values(req)
+	if err != nil {
+		return nil, fmt.Errorf("structured geocode query: %w", err)
+	}
+	//var api_error Error
+	resp, err := s.client.R().
+		SetQueryParamsFromValues(query).
+		SetContext(ctx).
+		SetResult(&result).
+		SetPathParam("urlBase", s.urlBase).
+		SetQueryParam("api_key", s.APIKey).
+		Get("https://{urlBase}/geocoding/v2/autocomplete")
+	if err != nil {
+		return nil, fmt.Errorf("autocomplete get: %w", err)
+	}
+
+	if !resp.IsSuccess() {
+		return nil, parseError(resp)
+	}
+	return &result, nil
+}