Geocoding Service (#35)

geocoding/handler/handler.go

@@ -0,0 +1,104 @@
+package handler
+
+import (
+	"context"
+	"strings"
+
+	"github.com/micro/micro/v3/service/errors"
+	"github.com/micro/micro/v3/service/logger"
+	"googlemaps.github.io/maps"
+
+	pb "github.com/micro/services/geocoding/proto"
+)
+
+var (
+	ErrDownstream       = errors.InternalServerError("MAP_ERROR", "Unable to connect to map provider")
+	ErrNoResults        = errors.BadRequest("NO_RESULTS", "Unable to geocode address, no results found")
+	ErrMissingLatitude  = errors.BadRequest("MISSING_LATITUDE", "Missing latitude")
+	ErrMissingLongitude = errors.BadRequest("MISSING_LONGITUDE", "Missing longitude")
+)
+
+type Geocoding struct {
+	Maps *maps.Client
+}
+
+// Geocode an address
+func (g *Geocoding) Geocode(ctx context.Context, req *pb.Address, rsp *pb.Address) error {
+	// query google maps
+	results, err := g.Maps.Geocode(ctx, &maps.GeocodingRequest{Address: toString(req)})
+	if err != nil {
+		logger.Errorf("Error geocoding: %v", err)
+		return ErrDownstream
+	}
+	if len(results) == 0 {
+		return ErrNoResults
+	}
+
+	// return the result
+	serializeResult(results[0], rsp)
+	return nil
+}
+
+// Reverse geocode an address
+func (g *Geocoding) Reverse(ctx context.Context, req *pb.Coordinates, rsp *pb.Address) error {
+	// validate the request
+	if req.Latitude == nil {
+		return ErrMissingLatitude
+	}
+	if req.Longitude == nil {
+		return ErrMissingLongitude
+	}
+
+	// query google maps
+	results, err := g.Maps.ReverseGeocode(ctx, &maps.GeocodingRequest{
+		LatLng: &maps.LatLng{Lat: req.Latitude.Value, Lng: req.Longitude.Value},
+	})
+	if err != nil {
+		logger.Errorf("Error geocoding: %v", err)
+		return ErrDownstream
+	}
+	if len(results) == 0 {
+		return ErrNoResults
+	}
+
+	// return the result
+	serializeResult(results[0], rsp)
+	return nil
+}
+
+func toString(a *pb.Address) string {
+	var comps []string
+	for _, c := range []string{a.LineOne, a.LineTwo, a.City, a.Postcode, a.Country} {
+		t := strings.TrimSpace(c)
+		if len(t) > 0 {
+			comps = append(comps, t)
+		}
+	}
+	return strings.Join(comps, ", ")
+}
+
+func serializeResult(r maps.GeocodingResult, a *pb.Address) {
+	var street, number string
+	for _, c := range r.AddressComponents {
+		for _, t := range c.Types {
+			switch t {
+			case "street_number":
+				number = c.LongName
+			case "route":
+				street = c.LongName
+			case "neighborhood":
+				a.LineTwo = c.LongName
+			case "country":
+				a.Country = c.LongName
+			case "postal_code":
+				a.Postcode = c.LongName
+			case "postal_town":
+				a.City = c.LongName
+			}
+		}
+	}
+
+	a.LineOne = strings.Join([]string{number, street}, " ")
+	a.Latitude = r.Geometry.Location.Lat
+	a.Longitude = r.Geometry.Location.Lng
+}