implemented critical features in Restful Golang API which'll handle Neo4j interactions.

backend/auth.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	// "log"
+	"net/http"
+	"os"
+	// "strconv"
+	"strings"
+
+	"github.com/golang-jwt/jwt"
+)
+
+// Define a custom context key for storing user information
+var userCtxKey = &contextKey{"user"}
+
+type contextKey struct {
+	name string
+}
+
+// AuthMiddleware is our JWT verification middleware
+func auth_middleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// 1. Extract the JWT from the request (e.g., Authorization header)
+		authHeader := r.Header.Get("Authorization")
+		if authHeader == "" {
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+			return
+		}
+
+		tokenString := ""
+		parts := strings.Split(authHeader, " ")
+		if len(parts) == 2 && strings.ToLower(parts[0]) == "bearer" {
+			tokenString = parts[1]
+		} else {
+			http.Error(w, "Invalid Authorization header format", http.StatusUnauthorized)
+			return
+		}
+
+		// 2. Verify the JWT
+		token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
+			// Validate the signing method
+			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+				return nil, fmt.Errorf("invalid signing method: %v", token.Header["alg"])
+			}
+			// Replace "your-secret-key" with your actual secret key
+			return []byte(os.Getenv("JWT_SECRET_KEY")), nil
+		})
+
+		if err != nil {
+			http.Error(w, "Invalid token", http.StatusUnauthorized)
+			return
+		}
+
+		if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
+			// 3. Optionally, extract user information from the claims and add it to the request context
+			user_id_raw, ok := claims["user_id"].(float64)
+			if !ok {
+				http.Error(w, "Invalid user ID in token", http.StatusInternalServerError)
+				return
+			}
+
+			user_id := int(user_id_raw)
+
+			// Create a new context with the user information
+			ctx := context.WithValue(r.Context(), userCtxKey, user_id)
+			// Call the next handler in the chain, passing the new context
+			next.ServeHTTP(w, r.WithContext(ctx))
+		} else {
+			http.Error(w, "Invalid token claims", http.StatusUnauthorized)
+			return
+		}
+	})
+}
+
+// Helper function to extract user information from the context in your handlers
+func user_id_from_context(ctx context.Context) (int, bool) {
+	userID, ok := ctx.Value(userCtxKey).(int)
+	return userID, ok
+}