Update endpoint -> subject encoding

Use an encoding that can be safely used bidirectionally while still being easy to read.
This is useful for being able to make HTTP requests from NATS, which I am working on now.

main.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"net"
 	"net/http"
+	"net/url"
 	"os"
 	"strings"
 	"time"
@@ -29,6 +30,27 @@ func printHelp() {
 	fmt.Println("    HTTP_PORT - HTTP port to listen on (default: 8080)")
 }
 
+// URL to NATS subject conversion
+func URLToNATS(urlPath string) (string, error) {
+	segments := strings.Split(strings.Trim(urlPath, "/"), "/")
+	for i, seg := range segments {
+		// Decode existing encoding first to prevent double-encoding
+		unescaped, err := url.PathUnescape(seg)
+		if err != nil {
+			return "", fmt.Errorf("failed to unescape segment: %w", err)
+		}
+
+		// Encode special NATS-sensitive characters
+		encoded := url.PathEscape(unescaped)
+		encoded = strings.ReplaceAll(encoded, ".", "%2E") // Critical for token separation
+		encoded = strings.ReplaceAll(encoded, "*", "%2A") // Wildcard protection
+		encoded = strings.ReplaceAll(encoded, ">", "%3E") // Wildcard protection
+
+		segments[i] = encoded
+	}
+	return strings.Join(segments, "."), nil
+}
+
 func main() {
 	helpFlag := flag.Bool("help", false, "Display help information about available environment variables")
 	flag.Parse()
@@ -103,9 +125,14 @@ func main() {
 		domainParts := strings.ReplaceAll(host, ".", "_")
 
 		// Process path component
-		path := strings.TrimPrefix(r.URL.Path, "/")
-		// Replace all "." with "_" and then all "/" with ".".
-		subjectPath := strings.ReplaceAll(strings.ReplaceAll(path, ".", "_"), "/", ".")
+		path := strings.TrimSuffix(strings.TrimPrefix(r.URL.Path, "/"), "/")
+		subjectPath, err := URLToNATS(path)
+		if err != nil {
+			http.Error(w, "Error converting endpoint to NATS subject", http.StatusInternalServerError)
+			log.Println("Could not convert endpoint to NATS subject", err)
+			return
+
+		}
 
 		// Build final subject
 		subjectBase := "http"