frontend: more organization

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

src/frontend/handlers.go

@@ -2,11 +2,14 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"html/template"
 	"log"
 	"net/http"
 
 	"github.com/google/uuid"
+
+	pb "frontend/genproto"
 )
 
 var (
@@ -36,8 +39,7 @@ func ensureSessionID(next http.HandlerFunc) http.HandlerFunc {
 				MaxAge: cookieMaxAge,
 			})
 		} else if err != nil {
-			log.Printf("unrecognized cookie error: %+v", err)
-			w.WriteHeader(http.StatusInternalServerError)
+			http.Error(w, fmt.Sprintf("unrecognized cookie error: %+v", err), http.StatusInternalServerError)
 			return
 		} else {
 			sessionID = c.Value
@@ -59,16 +61,32 @@ func (fe *frontendServer) homeHandler(w http.ResponseWriter, r *http.Request) {
 	log.Printf("currencies: %+v", currencies)
 	products, err := fe.getProducts(r.Context())
 	if err != nil {
-		log.Println(err)
-		w.WriteHeader(http.StatusInternalServerError)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 	log.Printf("# products: %d", len(products))
 
+	type productView struct {
+		Item  *pb.Product
+		Price *pb.Money
+	}
+	ps := make([]productView, len(products))
+	for i, p := range products {
+		price, err := fe.convertCurrency(r.Context(), &pb.Money{
+			Amount:       p.PriceUsd,
+			CurrencyCode: defaultCurrency,
+		}, currentCurrency(r))
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		ps[i] = productView{p, price}
+	}
+
 	if err := homeTemplate.Execute(w, map[string]interface{}{
 		"user_currency": currentCurrency(r),
 		"currencies":    currencies,
-		"products":      products,
+		"products":      ps,
 	}); err != nil {
 		log.Println(err)
 	}
@@ -76,8 +94,6 @@ func (fe *frontendServer) homeHandler(w http.ResponseWriter, r *http.Request) {
 
 func (fe *frontendServer) logoutHandler(w http.ResponseWriter, r *http.Request) {
 	log.Printf("[home] session_id=%+v", r.Context().Value(ctxKeySessionID{}))
-
-	// clear all cookies
 	for _, c := range r.Cookies() {
 		c.MaxAge = -1
 		http.SetCookie(w, c)

src/frontend/main.go

@@ -40,6 +40,7 @@ type frontendServer struct {
 
 func main() {
 	ctx := context.Background()
+	log.SetFlags(log.Lshortfile | log.Ltime)
 
 	srvPort := port
 	if os.Getenv("PORT") != "" {

src/frontend/rpc.go

@@ -6,6 +6,10 @@ import (
 	pb "frontend/genproto"
 )
 
+const (
+	avoidNoopCurrencyConversionRPC = false
+)
+
 func (fe *frontendServer) getCurrencies(ctx context.Context) ([]string, error) {
 	currs, err := pb.NewCurrencyServiceClient(fe.currencySvcConn).
 		GetSupportedCurrencies(ctx, &pb.Empty{})
@@ -26,3 +30,13 @@ func (fe *frontendServer) getProducts(ctx context.Context) ([]*pb.Product, error
 		ListProducts(ctx, &pb.Empty{})
 	return resp.GetProducts(), err
 }
+
+func (fe *frontendServer) convertCurrency(ctx context.Context, money *pb.Money, currency string) (*pb.Money, error) {
+	if avoidNoopCurrencyConversionRPC && money.GetCurrencyCode() == currency {
+		return money, nil
+	}
+	return pb.NewCurrencyServiceClient(fe.currencySvcConn).
+		Convert(ctx, &pb.CurrencyConversionRequest{
+			From:   money,
+			ToCode: currency})
+}

src/frontend/templates/home.html

@@ -17,7 +17,9 @@
         </select>
     </form>
     
-
     <p>{{ len $.products }} products</p>
+    {{range $.products }}
+    <p>{{.Item.Name}} -- <{{.Price}}></p>
+    {{end}}
 </body>
 </html>