Add CORS middleware using rs/cors package for improved handling

go.mod

@@ -8,6 +8,8 @@ require (
 	github.com/spf13/viper v1.19.0
 )
 
+require github.com/rs/cors v1.11.1 // indirect
+
 require (
 	github.com/coreos/go-oidc/v3 v3.12.0
 	github.com/fsnotify/fsnotify v1.7.0 // indirect

go.sum

@@ -40,6 +40,8 @@ github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRI
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
 github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/rs/cors v1.11.1 h1:eU3gRzXLRK57F5rKMGMZURNdIG4EoAmX8k94r9wXWHA=
+github.com/rs/cors v1.11.1/go.mod h1:XyqrcTp5zjWr1wsJ8PIRZssZ8b/WMcMf71DJnit4EMU=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/sagikazarmark/locafero v0.4.0 h1:HApY1R9zGo4DBgr7dqsTH/JJxLTTsOt7u6keLGt6kNQ=
 github.com/sagikazarmark/locafero v0.4.0/go.mod h1:Pe1W6UlPYUk/+wc/6KFhbORCfqzgYEpgQ3O5fPuL3H4=

internal/middleware/cors.go

@@ -2,8 +2,8 @@ package middleware
 
 import (
 	"net/http"
-	"strconv"
-	"strings"
+
+	"github.com/rs/cors"
 )
 
 // CORSConfig defines the configuration options for CORS middleware
@@ -42,80 +42,16 @@ func DefaultCORSConfig() CORSConfig {
 
 // CORS middleware handles Cross-Origin Resource Sharing
 func CORS(config CORSConfig) Middleware {
-	// Precompute values for better performance
-	allowedOriginsMap := make(map[string]bool)
-	for _, origin := range config.AllowedOrigins {
-		allowedOriginsMap[origin] = true
-	}
-
-	allowAllOrigins := allowedOriginsMap["*"]
-	allowedMethodsValue := strings.Join(config.AllowedMethods, ", ")
-	allowedHeadersValue := strings.Join(config.AllowedHeaders, ", ")
-	exposedHeadersValue := strings.Join(config.ExposedHeaders, ", ")
-
-	// Convert MaxAge to a string once
-	var maxAgeValue string
-	if config.MaxAge > 0 {
-		maxAgeValue = strconv.Itoa(config.MaxAge)
-	}
+	c := cors.New(cors.Options{
+		AllowedOrigins:   config.AllowedOrigins,
+		AllowedMethods:   config.AllowedMethods,
+		AllowedHeaders:   config.AllowedHeaders,
+		ExposedHeaders:   config.ExposedHeaders,
+		AllowCredentials: config.AllowCredentials,
+		MaxAge:           config.MaxAge,
+	})
 
 	return func(next http.Handler) http.Handler {
-		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			origin := r.Header.Get("Origin")
-
-			// Skip if no Origin header is present (same-origin request)
-			if origin == "" {
-				next.ServeHTTP(w, r)
-				return
-			}
-
-			// Check if the origin is allowed
-			var allowedOrigin string
-			if allowAllOrigins {
-				allowedOrigin = origin
-			} else if allowedOriginsMap[origin] {
-				allowedOrigin = origin
-			}
-
-			// Preflight OPTIONS request
-			if r.Method == http.MethodOptions {
-				// Set allowed methods
-				w.Header().Set("Access-Control-Allow-Methods", allowedMethodsValue)
-
-				// Set allowed headers
-				if len(allowedHeadersValue) > 0 {
-					w.Header().Set("Access-Control-Allow-Headers", allowedHeadersValue)
-				}
-
-				// Set max age for preflight request caching
-				if maxAgeValue != "" {
-					w.Header().Set("Access-Control-Max-Age", maxAgeValue)
-				}
-			}
-
-			// Set allowed origin
-			if allowedOrigin != "" {
-				w.Header().Set("Access-Control-Allow-Origin", allowedOrigin)
-			}
-
-			// Set exposed headers
-			if len(exposedHeadersValue) > 0 {
-				w.Header().Set("Access-Control-Expose-Headers", exposedHeadersValue)
-			}
-
-			// Set allow credentials
-			if config.AllowCredentials {
-				w.Header().Set("Access-Control-Allow-Credentials", "true")
-			}
-
-			// If it's a preflight request, we're done
-			if r.Method == http.MethodOptions {
-				w.WriteHeader(http.StatusNoContent)
-				return
-			}
-
-			// Process the actual request
-			next.ServeHTTP(w, r)
-		})
+		return c.Handler(next)
 	}
 }