extended input validation

giteainstall

@@ -119,6 +119,20 @@ if [[ ! "$hostname" =~ ^([a-z0-9]+(-[a-z0-9]+)*\.)+[a-z]{2,}$ ]]; then
     exit 1
 fi
 
+# Prevent accidental overwrite of existing Nginx config
+if [[ -f "/etc/nginx/conf.d/${hostname}.conf" ]]; then
+    printf "\nERROR: A configuration file already exists for %s.\n" "$hostname"
+    printf "Refusing to overwrite existing site.\n\n"
+    exit 1
+fi
+
+# Check for existing references in other Nginx configs
+hostcheck=$(grep -r --exclude="README.md" "$hostname" /etc/nginx/ 2>/dev/null || true)
+if [[ -n "$hostcheck" ]]; then
+    printf "\nFound existing configuration mentioning %s — aborting to avoid collision.\n\n" "$hostname"
+    exit 1
+fi
+
 # Check for spaces in DB credentials
 if [[ "$dbpass" =~ [[:space:]] ]]; then
     printf "\nERROR: Database password cannot contain spaces.\n\n"