feat: interactive setup wizard for first-run and netssh configure

- Auto-detects missing config (netbox.url empty) and launches wizard
- `netssh configure` re-runs the wizard anytime to change settings
- 3-page huh form: NetBox connection, SSH defaults, resolver & cache
- Saves to ~/.config/netssh.yaml (permissions 0600)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/config/config.go

@@ -35,6 +35,15 @@ type SSHConfig struct {
 	DefaultUser string `mapstructure:"default_user"`
 }
 
+// Path returns the canonical config file path.
+func Path() string {
+	configDir, err := os.UserConfigDir()
+	if err != nil {
+		configDir = filepath.Join(os.Getenv("HOME"), ".config")
+	}
+	return filepath.Join(configDir, "netssh.yaml")
+}
+
 func Load() (*Config, error) {
 	v := viper.New()
 

internal/setup/wizard.go

@@ -0,0 +1,175 @@
+package setup
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/charmbracelet/huh"
+
+	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/config"
+)
+
+// RunWizard runs the interactive setup form, pre-filled with any existing cfg values.
+// It saves the result to the config file on success.
+func RunWizard(cfg *config.Config) error {
+	url := cfg.NetBox.URL
+	token := cfg.NetBox.Token
+	defaultUser := cfg.SSH.DefaultUser
+	strategies := cfg.Resolver.Strategies
+	subnets := strings.Join(cfg.Resolver.ManagementSubnets, ", ")
+	interfaceName := cfg.Resolver.InterfaceName
+	cacheTTL := strconv.Itoa(cfg.Cache.TTL)
+
+	if len(strategies) == 0 {
+		strategies = []string{"primary_ip"}
+	}
+	if cacheTTL == "0" {
+		cacheTTL = "3600"
+	}
+
+	form := huh.NewForm(
+		huh.NewGroup(
+			huh.NewInput().
+				Title("NetBox URL").
+				Description("e.g. https://netbox.example.com").
+				Placeholder("https://").
+				Value(&url).
+				Validate(func(s string) error {
+					if strings.TrimSpace(s) == "" {
+						return errors.New("required")
+					}
+					return nil
+				}),
+			huh.NewInput().
+				Title("NetBox API token").
+				EchoMode(huh.EchoModePassword).
+				Value(&token).
+				Validate(func(s string) error {
+					if strings.TrimSpace(s) == "" {
+						return errors.New("required")
+					}
+					return nil
+				}),
+		).Title("NetBox connection"),
+
+		huh.NewGroup(
+			huh.NewInput().
+				Title("Default SSH user").
+				Description("Leave empty to use your system user ($USER).").
+				Value(&defaultUser),
+		).Title("SSH defaults"),
+
+		huh.NewGroup(
+			huh.NewMultiSelect[string]().
+				Title("Resolver strategies").
+				Description("Order matters: first match wins.").
+				Options(
+					huh.NewOption("primary_ip  — NetBox primary IPv4/IPv6", "primary_ip"),
+					huh.NewOption("management_subnet  — first IP inside a subnet", "management_subnet"),
+					huh.NewOption("interface_name  — IP on a named interface", "interface_name"),
+				).
+				Value(&strategies),
+			huh.NewInput().
+				Title("Management subnets").
+				Description("Comma-separated CIDRs, e.g. 10.0.0.0/8, 192.168.0.0/16\nOnly used when management_subnet strategy is active.").
+				Value(&subnets),
+			huh.NewInput().
+				Title("Interface name").
+				Description("Only used when interface_name strategy is active.").
+				Placeholder("eth0").
+				Value(&interfaceName),
+			huh.NewInput().
+				Title("Cache TTL (seconds)").
+				Value(&cacheTTL).
+				Validate(func(s string) error {
+					if _, err := strconv.Atoi(s); err != nil {
+						return errors.New("must be a number")
+					}
+					return nil
+				}),
+		).Title("Resolver & cache"),
+	)
+
+	if err := form.Run(); err != nil {
+		if errors.Is(err, huh.ErrUserAborted) {
+			fmt.Fprintln(os.Stderr, "Setup cancelled.")
+			os.Exit(0)
+		}
+		return err
+	}
+
+	ttl, _ := strconv.Atoi(cacheTTL)
+
+	var subnetList []string
+	for _, s := range strings.Split(subnets, ",") {
+		if s = strings.TrimSpace(s); s != "" {
+			subnetList = append(subnetList, s)
+		}
+	}
+
+	out := config.Config{
+		NetBox: config.NetBoxConfig{
+			URL:   strings.TrimRight(strings.TrimSpace(url), "/"),
+			Token: strings.TrimSpace(token),
+		},
+		SSH: config.SSHConfig{
+			DefaultUser: strings.TrimSpace(defaultUser),
+		},
+		Resolver: config.ResolverConfig{
+			Strategies:        strategies,
+			ManagementSubnets: subnetList,
+			InterfaceName:     strings.TrimSpace(interfaceName),
+		},
+		Cache: config.CacheConfig{
+			TTL: ttl,
+		},
+	}
+
+	return save(out)
+}
+
+func save(cfg config.Config) error {
+	path := config.Path()
+	if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
+		return fmt.Errorf("creating config dir: %w", err)
+	}
+
+	var b strings.Builder
+	b.WriteString("netbox:\n")
+	b.WriteString(fmt.Sprintf("  url: %q\n", cfg.NetBox.URL))
+	b.WriteString(fmt.Sprintf("  token: %q\n", cfg.NetBox.Token))
+
+	b.WriteString("\nresolver:\n")
+	b.WriteString("  strategies:\n")
+	for _, s := range cfg.Resolver.Strategies {
+		fmt.Fprintf(&b, "    - %s\n", s)
+	}
+	if len(cfg.Resolver.ManagementSubnets) > 0 {
+		b.WriteString("  management_subnets:\n")
+		for _, s := range cfg.Resolver.ManagementSubnets {
+			fmt.Fprintf(&b, "    - %s\n", s)
+		}
+	}
+	if cfg.Resolver.InterfaceName != "" {
+		fmt.Fprintf(&b, "  interface_name: %q\n", cfg.Resolver.InterfaceName)
+	}
+
+	b.WriteString("\ncache:\n")
+	fmt.Fprintf(&b, "  ttl: %d\n", cfg.Cache.TTL)
+
+	b.WriteString("\nssh:\n")
+	if cfg.SSH.DefaultUser != "" {
+		fmt.Fprintf(&b, "  default_user: %q\n", cfg.SSH.DefaultUser)
+	}
+
+	if err := os.WriteFile(path, []byte(b.String()), 0o600); err != nil {
+		return fmt.Errorf("writing config: %w", err)
+	}
+
+	fmt.Printf("\nConfig saved → %s\n", path)
+	return nil
+}