add missing code and might be ready for merge

cmd/checkout/cart-client.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"net/http"
+	"time"
+
+	"git.k6n.net/go-cart-actor/pkg/cart"
+	"github.com/gogo/protobuf/proto"
+)
+
+type CartClient struct {
+	httpClient *http.Client
+	baseUrl    string
+}
+
+func NewCartClient(baseUrl string) *CartClient {
+	return &CartClient{
+		httpClient: &http.Client{Timeout: 10 * time.Second},
+		baseUrl:    baseUrl,
+	}
+}
+
+func (c *CartClient) ApplyMutation(cartId cart.CartId, mutation proto.Message) error {
+	url := fmt.Sprintf("%s/internal/cart/%s/mutation", c.baseUrl, cartId.String())
+	data, err := proto.Marshal(mutation)
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequest("POST", url, bytes.NewReader(data))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/protobuf")
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("cart mutation failed: %s", resp.Status)
+	}
+	return nil
+}