refactor: Restructure project files for better organization, readability, and maintainability

internal/handler.go

@@ -0,0 +1,132 @@
+package pkg
+
+/*
+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 (
+	"encoding/json"
+	"github.com/gorilla/mux"
+	"github.com/jkaninda/goma-gateway/pkg/logger"
+	"net/http"
+	"sync"
+)
+
+// CORSHandler handles CORS headers for incoming requests
+//
+// Adds CORS headers to the response dynamically based on the provided headers map[string]string
+func CORSHandler(cors Cors) mux.MiddlewareFunc {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// Set CORS headers from the cors config
+			//Update Cors Headers
+			for k, v := range cors.Headers {
+				w.Header().Set(k, v)
+			}
+			//Update Origin Cors Headers
+			if allowedOrigin(cors.Origins, r.Header.Get("Origin")) {
+				// Handle preflight requests (OPTIONS)
+				if r.Method == "OPTIONS" {
+					w.Header().Set(accessControlAllowOrigin, r.Header.Get("Origin"))
+					w.WriteHeader(http.StatusNoContent)
+					return
+				} else {
+					w.Header().Set(accessControlAllowOrigin, r.Header.Get("Origin"))
+				}
+			}
+			// Pass the request to the next handler
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+// ProxyErrorHandler catches backend errors and returns a custom response
+func ProxyErrorHandler(w http.ResponseWriter, r *http.Request, err error) {
+	logger.Error("Proxy error: %v", err)
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusBadGateway)
+	err = json.NewEncoder(w).Encode(map[string]interface{}{
+		"success": false,
+		"code":    http.StatusBadGateway,
+		"message": "The service is currently unavailable. Please try again later.",
+	})
+	if err != nil {
+		return
+	}
+	return
+}
+
+// HealthCheckHandler handles health check of routes
+func (heathRoute HealthCheckRoute) HealthCheckHandler(w http.ResponseWriter, r *http.Request) {
+	logger.Info("%s %s %s %s", r.Method, r.RemoteAddr, r.URL, r.UserAgent())
+	wg := sync.WaitGroup{}
+	wg.Add(len(heathRoute.Routes))
+	var routes []HealthCheckRouteResponse
+	for _, route := range heathRoute.Routes {
+		go func() {
+			if route.HealthCheck != "" {
+				err := HealthCheck(route.Destination + route.HealthCheck)
+				if err != nil {
+					if heathRoute.DisableRouteHealthCheckError {
+						routes = append(routes, HealthCheckRouteResponse{Name: route.Name, Status: "unhealthy", Error: "Route healthcheck errors disabled"})
+					}
+					routes = append(routes, HealthCheckRouteResponse{Name: route.Name, Status: "unhealthy", Error: "Error: " + err.Error()})
+				} else {
+					logger.Info("Route %s is healthy", route.Name)
+					routes = append(routes, HealthCheckRouteResponse{Name: route.Name, Status: "healthy", Error: ""})
+				}
+			} else {
+				logger.Warn("Route %s's healthCheck is undefined", route.Name)
+				routes = append(routes, HealthCheckRouteResponse{Name: route.Name, Status: "undefined", Error: ""})
+			}
+			defer wg.Done()
+		}()
+
+	}
+	wg.Wait() // Wait for all requests to complete
+	response := HealthCheckResponse{
+		Status: "healthy", //Goma proxy
+		Routes: routes,    // Routes health check
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	err := json.NewEncoder(w).Encode(response)
+	if err != nil {
+		return
+	}
+}
+func (heathRoute HealthCheckRoute) HealthReadyHandler(w http.ResponseWriter, r *http.Request) {
+	logger.Info("%s %s %s %s", r.Method, r.RemoteAddr, r.URL, r.UserAgent())
+	response := HealthCheckRouteResponse{
+		Name:   "Goma Gateway",
+		Status: "healthy",
+		Error:  "",
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	err := json.NewEncoder(w).Encode(response)
+	if err != nil {
+		return
+	}
+}
+func allowedOrigin(origins []string, origin string) bool {
+	for _, o := range origins {
+		if o == origin {
+			return true
+		}
+		continue
+	}
+	return false
+
+}