// +build linux

package main

import (
	"fmt"
	"os"
	"syscall"
)

// scutil --get ComputerName

// getDomainName fetches the domain name using the getdomainname syscall.
func getDomainName() (string, error) {
	var buf [256]byte
	err := syscall.Getdomainname(buf[:])
	if err != nil {
		return "", fmt.Errorf("failed to get domain name: %w", err)
	}
	// Trim null bytes
	n := 0
	for ; n < len(buf); n++ {
		if buf[n] == 0 {
			break
		}
	}
	return string(buf[:n]), nil
}

// GetFullHostname returns the hostname + domain name (if set).
func GetFullHostname() (string, error) {
	host, err := os.Hostname()
	if err != nil {
		return "", fmt.Errorf("failed to get hostname: %w", err)
	}

	domain, err := getDomainName()
	if err != nil || domain == "" {
		return host, nil // fallback to short hostname
	}

	return fmt.Sprintf("%s.%s", host, domain), nil
}

func main() {
	fqdn, err := GetFullHostname()
	if err != nil {
		fmt.Println("Error:", err)
		return
	}
	fmt.Println("Hostname + Domain:", fqdn)
}