fix: return empty response if no destinations are provided

main.go

@@ -4,21 +4,22 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"github.com/caarlos0/env"
-	"googlemaps.github.io/maps"
 	"log"
 	"net/http"
 	"strconv"
 	"strings"
+
+	"github.com/caarlos0/env"
+	"googlemaps.github.io/maps"
 )
 
 type config struct {
 	MapsApiKey string `env:"MAPS_API_KEY"`
-	Port int `env:"PORT" envDefault:"80"`
+	Port       int    `env:"PORT" envDefault:"80"`
 }
 
 type location struct {
-	Lat float64 `json:"latitude"`
+	Lat  float64 `json:"latitude"`
 	Long float64 `json:"longitude"`
 }
 
@@ -27,23 +28,23 @@ type address struct {
 }
 
 type distance struct {
-	Text string `json:"text"`
-	Value int `json:"value"`
+	Text  string `json:"text"`
+	Value int    `json:"value"`
 }
 
 type duration struct {
-	Text string `json:"text"`
+	Text  string  `json:"text"`
 	Value float64 `json:"value"`
 }
 
 type destination struct {
-	Destination string `json:"destination"`
-	Distance distance `json:"distance"`
-	Duration duration `json:"duration"`
+	Destination string   `json:"destination"`
+	Distance    distance `json:"distance"`
+	Duration    duration `json:"duration"`
 }
 
 type origin struct {
-	Origin string `json:"origin"`
+	Origin       string        `json:"origin"`
 	Destinations []destination `json:"destinations"`
 }
 
@@ -78,13 +79,22 @@ func makeHandler(fn func(http.ResponseWriter, *http.Request, *maps.Client), clie
 
 func handleDistanceMatrixRequest(w http.ResponseWriter, r *http.Request, client *maps.Client) {
 	origins := strings.Split(r.URL.Query().Get("origins"), "|")
-	destinations := strings.Split(r.URL.Query().Get("destinations"), "|")
+	destinationsString := r.URL.Query().Get("destinations")
+	if destinationsString == "" {
+		x := make([]origin, len(origins))
+		for i, o := range origins {
+			x[i] = origin{Origin: o}
+		}
+		writeResponse(distanceResponse{Origins: x}, w)
+		return
+	}
+	destinations := strings.Split(destinationsString, "|")
 
 	req := &maps.DistanceMatrixRequest{
-		Origins: origins,
+		Origins:      origins,
 		Destinations: destinations,
-		Language: "sv",
-		Units: maps.UnitsMetric,
+		Language:     "sv",
+		Units:        maps.UnitsMetric,
 	}
 
 	if result, err := client.DistanceMatrix(context.Background(), req); err != nil {
@@ -111,12 +121,16 @@ func handleDistanceMatrixRequest(w http.ResponseWriter, r *http.Request, client
 			res.Origins = append(res.Origins, origin{origins[i], dests})
 		}
 
-		if response, err := json.Marshal(res); err != nil {
-			log.Fatalf("fatal error: %s", err)
-			w.WriteHeader(404)
-		} else {
-			_, _ = w.Write(response)
-		}
+		writeResponse(res, w)
+	}
+}
+
+func writeResponse(res distanceResponse, w http.ResponseWriter) {
+	if response, err := json.Marshal(res); err != nil {
+		log.Fatalf("fatal error: %s", err)
+		w.WriteHeader(404)
+	} else {
+		_, _ = w.Write(response)
 	}
 }
 
@@ -133,7 +147,7 @@ func handleAddressRequest(w http.ResponseWriter, r *http.Request, client *maps.C
 	} else {
 		if len(result) > 0 {
 			l := address{
-				Address:          result[0].FormattedAddress,
+				Address: result[0].FormattedAddress,
 			}
 			if response, err := json.Marshal(l); err != nil {
 				log.Fatalf("fatal error: %s", err)
@@ -147,15 +161,15 @@ func handleAddressRequest(w http.ResponseWriter, r *http.Request, client *maps.C
 
 func handleLatLongRequest(w http.ResponseWriter, r *http.Request, client *maps.Client) {
 	req := &maps.GeocodingRequest{
-		Address:      r.URL.Path[len("/latlong/"):],
+		Address: r.URL.Path[len("/latlong/"):],
 	}
 	if result, err := client.Geocode(context.Background(), req); err != nil {
 		w.WriteHeader(400)
 	} else {
 		if len(result) > 0 {
 			l := location{
-				Lat:          result[0].Geometry.Location.Lat,
-				Long:         result[0].Geometry.Location.Lng,
+				Lat:  result[0].Geometry.Location.Lat,
+				Long: result[0].Geometry.Location.Lng,
 			}
 			if response, err := json.Marshal(l); err != nil {
 				w.WriteHeader(500)
@@ -163,7 +177,7 @@ func handleLatLongRequest(w http.ResponseWriter, r *http.Request, client *maps.C
 				_, _ = w.Write(response)
 			}
 		} else {
-		  w.WriteHeader(404)
-    }
+			w.WriteHeader(404)
+		}
 	}
 }