[hw-7] add metrics, tracing

cart/internal/infra/http/middlewares/metrics.go

@@ -0,0 +1,38 @@
+package middlewares
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+
+	"route256/cart/internal/infra/http/metrics"
+)
+
+type statusWriter struct {
+	http.ResponseWriter
+	statusCode int
+}
+
+func (w *statusWriter) WriteHeader(code int) {
+	w.statusCode = code
+	w.ResponseWriter.WriteHeader(code)
+}
+
+func NewMetricsMiddleware(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		sw := &statusWriter{
+			ResponseWriter: w,
+			statusCode:     http.StatusOK,
+		}
+
+		start := time.Now()
+
+		h.ServeHTTP(sw, r)
+
+		path := r.URL.Path
+		status := strconv.Itoa(sw.statusCode)
+
+		metrics.IncRequestHandlerCount(r.Method, path, status)
+		metrics.StoreHandlerRequestDuration(r.Method, path, status, time.Since(start))
+	})
+}