package internal

import (
	"fmt"
	"net"
	"strconv"
	"strings"
)

func ResolveLocalTCPAddress(addr string) (*net.TCPAddr, error) {
	// Resolve the local address into IP address and the given port if any
	host, port, err := net.SplitHostPort(addr)
	if err != nil {
		if !strings.Contains(err.Error(), "missing port") {
			return nil, fmt.Errorf("invalid local address: %w", err)
		}
		host = addr
	}
	local, err := net.ResolveIPAddr("ip", host)
	if err != nil {
		return nil, fmt.Errorf("cannot resolve local address: %w", err)
	}

	var portNo int
	if port != "" {
		p, err := strconv.ParseUint(port, 10, 16)
		if err != nil {
			return nil, fmt.Errorf("invalid port: %w", err)
		}
		portNo = int(p)
	}

	return &net.TCPAddr{IP: local.IP, Port: portNo, Zone: local.Zone}, nil
}