// SPDX-License-Identifier: Apache-2.0

// Package netutil holds tiny networking helpers shared across cmd/
// binaries. Kept deliberately minimal — anything more involved than a
// few lines belongs in its own package.
package netutil

import (
	"net"
	"strings"
)

// EnsurePort returns addr unchanged when it already carries a port, or
// addr with ":<defaultPort>" appended otherwise. Bare IPv6 literals
// ("2001:db8::1", "::1") are bracketed so the result is valid input to
// grpc.NewClient and net.Dial. An empty addr is returned unchanged.
func EnsurePort(addr, defaultPort string) string {
	if addr == "" {
		return addr
	}
	if _, _, err := net.SplitHostPort(addr); err == nil {
		return addr
	}
	// Already-bracketed bare IPv6 ("[::1]") falls through to the plain
	// concat at the bottom. Unbracketed IPv6 needs brackets first; we
	// detect it by handing the literal to net.ParseIP, which only
	// accepts the bare form (no brackets, no port).
	if ip := net.ParseIP(addr); ip != nil && ip.To4() == nil && strings.Contains(addr, ":") {
		return "[" + addr + "]:" + defaultPort
	}
	return addr + ":" + defaultPort
}