package setup

import (
	"net"
	"sort"
	"strings"
)

// DetectLocalIPs returns non-loopback, non-docker IPv4 addresses.
func DetectLocalIPs() []string {
	ifaces, err := net.Interfaces()
	if err != nil {
		return nil
	}

	var ips []string
	for _, iface := range ifaces {
		// Skip down, loopback, and Docker/container interfaces
		if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
			continue
		}
		name := strings.ToLower(iface.Name)
		if strings.HasPrefix(name, "docker") || strings.HasPrefix(name, "br-") ||
			strings.HasPrefix(name, "veth") || strings.HasPrefix(name, "lo") {
			continue
		}

		addrs, err := iface.Addrs()
		if err != nil {
			continue
		}
		for _, addr := range addrs {
			var ip net.IP
			switch v := addr.(type) {
			case *net.IPNet:
				ip = v.IP
			case *net.IPAddr:
				ip = v.IP
			}
			if ip == nil || ip.IsLoopback() || ip.To4() == nil {
				continue // skip non-IPv4
			}
			ips = append(ips, ip.String())
		}
	}

	sort.Strings(ips)
	return ips
}