checkoutservice prototype!!1

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

src/checkoutservice/main.go

@@ -7,15 +7,17 @@ import (
 	"net"
 	"os"
 
+	"github.com/google/uuid"
+	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 
 	pb "./genproto"
-	"google.golang.org/grpc"
 )
 
 const (
-	listenPort = "5050"
+	listenPort  = "5050"
+	usdCurrency = "USD"
 )
 
 type checkoutService struct {
@@ -64,30 +66,197 @@ func mustMapEnv(target *string, envKey string) {
 func (cs *checkoutService) CreateOrder(ctx context.Context, req *pb.CreateOrderRequest) (*pb.CreateOrderResponse, error) {
 	log.Printf("[CreateOrder] user_id=%q user_currency=%q", req.UserId, req.UserCurrency)
 	resp := new(pb.CreateOrderResponse)
-	conn, err := grpc.Dial(cs.shippingSvcAddr, grpc.WithInsecure())
-	if err != nil {
-		return nil, status.Errorf(codes.Unavailable, "could not connect shippping service: %+v", err)
-	}
-	defer conn.Close()
 
-	shippingQuote, err := pb.NewShippingServiceClient(conn).
+	shippingQuoteUSD, err := cs.quoteShipping(ctx, req.Address, nil) // TODO(ahmetb): query CartService for items
-		GetQuote(ctx, &pb.GetQuoteRequest{
-			Address: req.Address,
-			Items:   nil}) // TODO(ahmetb): query CartService for items
 	if err != nil {
-		return nil, status.Errorf(codes.Unavailable, "failed to get shipping quote: %+v", err)
+		return nil, status.Errorf(codes.Internal, "shipping quote failure: %+v", err)
 	}
 	resp.ShippingCost = &pb.Money{
-		Amount:       shippingQuote.GetCostUsd(),
+		Amount:       shippingQuoteUSD,
-		CurrencyCode: "USD", // TOD(ahmetb) convert to req.UserCurrency
+		CurrencyCode: "USD",
 	}
+	// TODO(ahmetb) convert to req.UserCurrency
 	// TODO(ahmetb) calculate resp.OrderItem with req.UserCurrency
-
 	return resp, nil
 }
 
 func (cs *checkoutService) PlaceOrder(ctx context.Context, req *pb.PlaceOrderRequest) (*pb.PlaceOrderResponse, error) {
 	log.Printf("[PlaceOrder] user_id=%q user_currency=%q", req.UserId, req.UserCurrency)
-	resp := new(pb.PlaceOrderResponse)
+
+	orderID, err := uuid.NewUUID()
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "failed to generate order uuid")
+	}
+
+	cartItems, err := cs.getUserCart(ctx, req.UserId)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "cart failure: %+v", err)
+	}
+
+	orderItems, err := cs.prepOrderItems(ctx, cartItems, req.UserCurrency)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "failed to prepare order: %+v", err)
+	}
+
+	shippingUsd, err := cs.quoteShipping(ctx, req.Address, cartItems) // TODO(ahmetb): query CartService for items
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "shipping quote failure: %+v", err)
+	}
+	shippingPrice, err := cs.convertCurrency(ctx, &pb.Money{
+		Amount:       shippingUsd,
+		CurrencyCode: usdCurrency}, req.UserCurrency)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "failed to convert shipping cost to currency: %+v", err)
+	}
+
+	var totalPrice pb.Money
+	totalPrice = sumMoney(totalPrice, *shippingPrice)
+	for _, it := range orderItems {
+		totalPrice = sumMoney(totalPrice, *it.Cost)
+	}
+
+	txID, err := cs.chargeCard(ctx, &totalPrice, req.CreditCard)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "failed to charge card: %+v", err)
+	}
+	log.Printf("payment went through (transaction_id: %s)", txID)
+
+	shippingTrackingID, err := cs.shipOrder(ctx, req.Address, cartItems)
+	if err != nil {
+		return nil, status.Errorf(codes.Unavailable, "shipping error: %+v", err)
+	}
+
+	orderResult := &pb.OrderResult{
+		OrderId:            orderID.String(),
+		ShippingTrackingId: shippingTrackingID,
+		ShippingCost:       shippingPrice,
+		ShippingAddress:    req.Address,
+		Items:              orderItems,
+	}
+
+	if err := cs.sendOrderConfirmation(ctx, req.Email, orderResult); err != nil {
+		log.Printf("failed to send order confirmation to %q: %+v", req.Email, err)
+	} else {
+		log.Printf("order confirmation email sent to %q", req.Email)
+	}
+	resp := &pb.PlaceOrderResponse{Order: orderResult}
 	return resp, nil
 }
+
+func (cs *checkoutService) quoteShipping(ctx context.Context, address *pb.Address, items []*pb.CartItem) (*pb.MoneyAmount, error) {
+	conn, err := grpc.DialContext(ctx, cs.shippingSvcAddr, grpc.WithInsecure())
+	if err != nil {
+		return nil, fmt.Errorf("could not connect shipping service: %+v", err)
+	}
+	defer conn.Close()
+
+	shippingQuote, err := pb.NewShippingServiceClient(conn).
+		GetQuote(ctx, &pb.GetQuoteRequest{
+			Address: address,
+			Items:   items})
+	if err != nil {
+		return nil, fmt.Errorf("failed to get shipping quote: %+v", err)
+	}
+	return shippingQuote.GetCostUsd(), nil
+}
+
+func (cs *checkoutService) getUserCart(ctx context.Context, userID string) ([]*pb.CartItem, error) {
+	conn, err := grpc.DialContext(ctx, cs.cartSvcAddr, grpc.WithInsecure())
+	if err != nil {
+		return nil, fmt.Errorf("could not connect cart service: %+v", err)
+	}
+	defer conn.Close()
+
+	cart, err := pb.NewCartServiceClient(conn).GetCart(ctx, &pb.GetCartRequest{UserId: userID})
+	if err != nil {
+		return nil, fmt.Errorf("failed to get user cart: %+v", err)
+	}
+	return cart.GetItems(), nil
+}
+
+func (cs *checkoutService) prepOrderItems(ctx context.Context, items []*pb.CartItem, userCurrency string) ([]*pb.OrderItem, error) {
+	out := make([]*pb.OrderItem, len(items))
+
+	conn, err := grpc.DialContext(ctx, cs.productCatalogSvcAddr, grpc.WithInsecure())
+	if err != nil {
+		return nil, fmt.Errorf("could not connect product catalog service: %+v", err)
+	}
+	defer conn.Close()
+	cl := pb.NewProductCatalogServiceClient(conn)
+
+	for i, item := range items {
+		product, err := cl.GetProduct(ctx, &pb.GetProductRequest{Id: item.GetProductId()})
+		if err != nil {
+			return nil, fmt.Errorf("failed to get product #%q", item.GetProductId())
+		}
+		usdPrice := &pb.Money{
+			Amount:       product.GetPriceUsd(),
+			CurrencyCode: usdCurrency}
+		price, err := cs.convertCurrency(ctx, usdPrice, userCurrency)
+		if err != nil {
+			return nil, fmt.Errorf("failed to convert price of %q to %s", item.GetProductId(), userCurrency)
+		}
+		out[i] = &pb.OrderItem{
+			Item: item,
+			Cost: price}
+	}
+	return out, nil
+}
+
+func (cs *checkoutService) convertCurrency(ctx context.Context, from *pb.Money, toCurrency string) (*pb.Money, error) {
+	conn, err := grpc.DialContext(ctx, cs.currencySvcAddr, grpc.WithInsecure())
+	if err != nil {
+		return nil, fmt.Errorf("could not connect currency service: %+v", err)
+	}
+	defer conn.Close()
+	result, err := pb.NewCurrencyServiceClient(conn).Convert(context.TODO(), &pb.CurrencyConversionRequest{
+		From:   from,
+		ToCode: toCurrency})
+	if err != nil {
+		return nil, fmt.Errorf("failed to convert currency: %+v", err)
+	}
+	return result, err
+}
+
+func (cs *checkoutService) chargeCard(ctx context.Context, amount *pb.Money, paymentInfo *pb.CreditCardInfo) (string, error) {
+	conn, err := grpc.DialContext(ctx, cs.paymentSvcAddr, grpc.WithInsecure())
+	if err != nil {
+		return "", fmt.Errorf("failed to connect payment service: %+v", err)
+	}
+	defer conn.Close()
+
+	paymentResp, err := pb.NewPaymentServiceClient(conn).Charge(ctx, &pb.ChargeRequest{
+		Amount:     amount,
+		CreditCard: paymentInfo})
+	if err != nil {
+		return "", fmt.Errorf("could not charge the card: %+v", err)
+	}
+	return paymentResp.GetTransactionId(), nil
+}
+
+func (cs *checkoutService) sendOrderConfirmation(ctx context.Context, email string, order *pb.OrderResult) error {
+	conn, err := grpc.DialContext(ctx, cs.emailSvcAddr, grpc.WithInsecure())
+	if err != nil {
+		return fmt.Errorf("failed to connect email service: %+v", err)
+	}
+	defer conn.Close()
+	_, err = pb.NewEmailServiceClient(conn).SendOrderConfirmation(ctx, &pb.SendOrderConfirmationRequest{
+		Email: email,
+		Order: order})
+	return err
+}
+
+func (cs *checkoutService) shipOrder(ctx context.Context, address *pb.Address, items []*pb.CartItem) (string, error) {
+	conn, err := grpc.DialContext(ctx, cs.shippingSvcAddr, grpc.WithInsecure())
+	if err != nil {
+		return "", fmt.Errorf("failed to connect email service: %+v", err)
+	}
+	defer conn.Close()
+	resp, err := pb.NewShippingServiceClient(conn).ShipOrder(ctx, &pb.ShipOrderRequest{
+		Address: address,
+		Items:   items})
+	if err != nil {
+		return "", fmt.Errorf("shipment failed: %+v", err)
+	}
+	return resp.GetTrackingId(), nil
+}

src/checkoutservice/money.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"math"
+
+	pb "./genproto"
+)
+
+func sum(m1, m2 pb.MoneyAmount) pb.MoneyAmount {
+	f1, f2 := float64(m1.Fractional), float64(m2.Fractional)
+	lg1 := math.Max(1, math.Ceil(math.Log10(f1)))
+	lg2 := math.Max(1, math.Ceil(math.Log10(f2)))
+	lgMax := math.Max(lg1, lg2)
+
+	dSum := m1.Decimal + m2.Decimal
+	o1 := f1 * math.Pow(10, lgMax-lg1)
+	o2 := f2 * math.Pow(10, lgMax-lg2)
+	fSum := o1 + o2
+	if fSum >= math.Pow(10, lgMax) {
+		fSum -= math.Pow(10, lgMax)
+		dSum++
+	}
+
+	for int(fSum)%10 == 0 && fSum != 0 {
+		fSum = float64(int(fSum) / 10)
+	}
+
+	return pb.MoneyAmount{
+		Decimal:    dSum,
+		Fractional: uint32(fSum)}
+}
+
+func sumMoney(m1, m2 pb.Money) pb.Money {
+	s := sum(*m1.Amount, *m2.Amount)
+	return pb.Money{
+		Amount:       &s,
+		CurrencyCode: m1.CurrencyCode}
+}

src/checkoutservice/money_test.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+
+	pb "./genproto"
+)
+
+func Test_sum(t *testing.T) {
+	type args struct {
+		m1 pb.MoneyAmount
+		m2 pb.MoneyAmount
+	}
+	tests := []struct {
+		name string
+		args args
+		want pb.MoneyAmount
+	}{
+		{
+			name: "no fractions",
+			args: args{pb.MoneyAmount{Decimal: 10}, pb.MoneyAmount{Decimal: 100}},
+			want: pb.MoneyAmount{Decimal: 110},
+		},
+		{
+			name: "same fraction digits",
+			args: args{pb.MoneyAmount{Decimal: 1, Fractional: 23}, pb.MoneyAmount{Decimal: 1, Fractional: 44}},
+			want: pb.MoneyAmount{Decimal: 2, Fractional: 67},
+		},
+		{
+			name: "different fraction digits",
+			args: args{pb.MoneyAmount{Decimal: 1, Fractional: 351}, pb.MoneyAmount{Decimal: 1, Fractional: 1}},
+			want: pb.MoneyAmount{Decimal: 2, Fractional: 451},
+		},
+		{
+			name: "redundant trailing zeroes are removed from fraction",
+			args: args{pb.MoneyAmount{Decimal: 1, Fractional: 351}, pb.MoneyAmount{Decimal: 1, Fractional: 349}},
+			want: pb.MoneyAmount{Decimal: 2, Fractional: 7},
+		},
+		{
+			name: "carry",
+			args: args{pb.MoneyAmount{Decimal: 1, Fractional: 5}, pb.MoneyAmount{Decimal: 1, Fractional: 5000000}},
+			want: pb.MoneyAmount{Decimal: 3},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := sum(tt.args.m1, tt.args.m2); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("sum(%v+%v) = %v, want=%v", tt.args.m1, tt.args.m2, got, tt.want)
+			}
+		})
+	}
+}