refactor: improve error interceptor

internal/middleware/route_error_interceptor.go

@@ -0,0 +1,58 @@
+package middleware
+
+/*
+ * Copyright 2024 Jonas Kaninda
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+import (
+	errorinterceptor "github.com/jkaninda/goma-gateway/pkg/error-interceptor"
+	"github.com/jkaninda/goma-gateway/pkg/logger"
+	"io"
+	"net/http"
+)
+
+// RouteErrorInterceptor contains backend status code errors to intercept
+type RouteErrorInterceptor struct {
+	Origins          []string
+	ErrorInterceptor errorinterceptor.ErrorInterceptor
+}
+
+// RouteErrorInterceptor Middleware intercepts backend route errors
+func (intercept RouteErrorInterceptor) RouteErrorInterceptor(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		rec := newResponseRecorder(w)
+		next.ServeHTTP(rec, r)
+		if canInterceptError(rec.statusCode, intercept.ErrorInterceptor.Errors) {
+			logger.Debug("Backend error")
+			logger.Error("An error occurred from the backend with the status code: %d", rec.statusCode)
+			//Update Origin Cors Headers
+			if allowedOrigin(intercept.Origins, r.Header.Get("Origin")) {
+				w.Header().Set("Access-Control-Allow-Origin", r.Header.Get("Origin"))
+			}
+			RespondWithError(w, rec.statusCode, http.StatusText(rec.statusCode), intercept.ErrorInterceptor)
+			return
+		} else {
+			// No error: write buffered response to client
+			w.WriteHeader(rec.statusCode)
+			_, err := io.Copy(w, rec.body)
+			if err != nil {
+				return
+			}
+			return
+
+		}
+
+	})
+}