feat: add alias file generation and management for shell hooks

- **Aliases**: Generate shell alias files (`aliases.sh` for bash/zsh, `netssh.fish` for fish) from cached hosts. Regenerate on each shell startup and cache refresh to keep aliases updated.
- **Hooks**: Extend shell hook functionality to include alias file support. Install and uninstall commands updated for bash, zsh, and fish.
- **Tests**: Add unit tests to verify alias file generation, path resolution, and idempotent hook installation.
- **Docs**: Update README with instructions for alias file usage, installation, and relation to hooks.

internal/hook/aliases.go

@@ -0,0 +1,82 @@
+package hook
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// AliasEntry holds a single shell alias mapping.
+type AliasEntry struct {
+	Name string // short alias name (e.g. "web01")
+	Host string // canonical NetBox hostname (e.g. "web01.example.com")
+}
+
+// AliasesPath returns the path for the bash/zsh aliases file.
+func AliasesPath() string {
+	cacheDir, err := os.UserCacheDir()
+	if err != nil {
+		cacheDir = filepath.Join(os.Getenv("HOME"), ".cache")
+	}
+	return filepath.Join(cacheDir, "netssh", "aliases.sh")
+}
+
+// FishAliasesPath returns the path for the fish conf.d aliases file.
+// Fish auto-sources every file in conf.d, so no explicit source line is needed.
+func FishAliasesPath() string {
+	configDir, err := os.UserConfigDir()
+	if err != nil {
+		configDir = filepath.Join(os.Getenv("HOME"), ".config")
+	}
+	return filepath.Join(configDir, "fish", "conf.d", "netssh.fish")
+}
+
+// WriteAliasFiles writes alias definitions to disk for all supported shells.
+//
+// The bash/zsh file (~/.cache/netssh/aliases.sh) is always written.
+// The fish file (~/.config/fish/conf.d/netssh.fish) is written only when
+// ~/.config/fish/ already exists (i.e. fish is configured on this system).
+func WriteAliasFiles(entries []AliasEntry) error {
+	if err := writeShAliasFile(entries); err != nil {
+		return err
+	}
+	writeFishAliasFile(entries) // best-effort — never blocks the caller on failure
+	return nil
+}
+
+func writeShAliasFile(entries []AliasEntry) error {
+	p := AliasesPath()
+	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
+		return fmt.Errorf("creating aliases dir: %w", err)
+	}
+	var b strings.Builder
+	b.WriteString("# netssh aliases — generated automatically, do not edit\n")
+	b.WriteString("# Regenerated on every shell start and after 'netssh cache refresh'.\n")
+	for _, e := range entries {
+		fmt.Fprintf(&b, "alias %s='netssh %s'\n", e.Name, e.Host)
+	}
+	return os.WriteFile(p, []byte(b.String()), 0o644)
+}
+
+func writeFishAliasFile(entries []AliasEntry) {
+	configDir, err := os.UserConfigDir()
+	if err != nil {
+		return
+	}
+	// Only write if fish is configured on this system.
+	if _, err := os.Stat(filepath.Join(configDir, "fish")); err != nil {
+		return
+	}
+	p := FishAliasesPath()
+	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
+		return
+	}
+	var b strings.Builder
+	b.WriteString("# netssh aliases — generated automatically, do not edit\n")
+	b.WriteString("# Regenerated on every shell start and after 'netssh cache refresh'.\n")
+	for _, e := range entries {
+		fmt.Fprintf(&b, "alias %s 'netssh %s'\n", e.Name, e.Host)
+	}
+	os.WriteFile(p, []byte(b.String()), 0o644) //nolint:errcheck
+}

internal/hook/aliases_test.go

@@ -0,0 +1,210 @@
+package hook_test
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/hook"
+)
+
+func TestAliasesPath_UnderCacheDir(t *testing.T) {
+	dir := t.TempDir()
+	orig := os.Getenv("XDG_CACHE_HOME")
+	os.Setenv("XDG_CACHE_HOME", dir)
+	defer os.Setenv("XDG_CACHE_HOME", orig)
+
+	p := hook.AliasesPath()
+	if !strings.HasPrefix(p, dir) {
+		t.Errorf("AliasesPath should be under XDG_CACHE_HOME, got %q", p)
+	}
+	if !strings.HasSuffix(p, "aliases.sh") {
+		t.Errorf("AliasesPath should end with aliases.sh, got %q", p)
+	}
+}
+
+func TestFishAliasesPath_UnderConfigDir(t *testing.T) {
+	dir := t.TempDir()
+	orig := os.Getenv("XDG_CONFIG_HOME")
+	os.Setenv("XDG_CONFIG_HOME", dir)
+	defer os.Setenv("XDG_CONFIG_HOME", orig)
+
+	p := hook.FishAliasesPath()
+	if !strings.HasPrefix(p, dir) {
+		t.Errorf("FishAliasesPath should be under XDG_CONFIG_HOME, got %q", p)
+	}
+	if !strings.HasSuffix(p, "netssh.fish") {
+		t.Errorf("FishAliasesPath should end with netssh.fish, got %q", p)
+	}
+}
+
+// TestWriteAliasFiles_ShFile verifies the bash/zsh file is always written.
+func TestWriteAliasFiles_ShFile(t *testing.T) {
+	cacheDir := t.TempDir()
+	orig := os.Getenv("XDG_CACHE_HOME")
+	os.Setenv("XDG_CACHE_HOME", cacheDir)
+	defer os.Setenv("XDG_CACHE_HOME", orig)
+
+	entries := []hook.AliasEntry{
+		{Name: "web01", Host: "web01.example.com"},
+		{Name: "db01", Host: "db01.example.com"},
+	}
+	if err := hook.WriteAliasFiles(entries); err != nil {
+		t.Fatalf("WriteAliasFiles: %v", err)
+	}
+
+	data, err := os.ReadFile(hook.AliasesPath())
+	if err != nil {
+		t.Fatalf("aliases.sh not created: %v", err)
+	}
+	content := string(data)
+
+	for _, want := range []string{
+		"alias web01='netssh web01.example.com'",
+		"alias db01='netssh db01.example.com'",
+	} {
+		if !strings.Contains(content, want) {
+			t.Errorf("aliases.sh missing %q\ncontent:\n%s", want, content)
+		}
+	}
+}
+
+// TestWriteAliasFiles_FishFile verifies the fish file is written when fish config dir exists.
+func TestWriteAliasFiles_FishFile(t *testing.T) {
+	configDir := t.TempDir()
+	orig := os.Getenv("XDG_CONFIG_HOME")
+	os.Setenv("XDG_CONFIG_HOME", configDir)
+	defer os.Setenv("XDG_CONFIG_HOME", orig)
+
+	// Create the fish config directory so WriteAliasFiles knows fish is set up.
+	fishDir := filepath.Join(configDir, "fish")
+	os.MkdirAll(fishDir, 0o755)
+
+	cacheDir := t.TempDir()
+	origCache := os.Getenv("XDG_CACHE_HOME")
+	os.Setenv("XDG_CACHE_HOME", cacheDir)
+	defer os.Setenv("XDG_CACHE_HOME", origCache)
+
+	entries := []hook.AliasEntry{{Name: "web01", Host: "web01.example.com"}}
+	if err := hook.WriteAliasFiles(entries); err != nil {
+		t.Fatalf("WriteAliasFiles: %v", err)
+	}
+
+	data, err := os.ReadFile(hook.FishAliasesPath())
+	if err != nil {
+		t.Fatalf("netssh.fish not created: %v", err)
+	}
+	if !strings.Contains(string(data), "alias web01 'netssh web01.example.com'") {
+		t.Errorf("fish alias file missing expected line\ncontent:\n%s", string(data))
+	}
+}
+
+// TestWriteAliasFiles_SkipsFishWhenNotConfigured verifies that fish file is NOT written
+// when fish is not set up (no ~/.config/fish directory).
+func TestWriteAliasFiles_SkipsFishWhenNotConfigured(t *testing.T) {
+	configDir := t.TempDir() // no fish subdir
+	orig := os.Getenv("XDG_CONFIG_HOME")
+	os.Setenv("XDG_CONFIG_HOME", configDir)
+	defer os.Setenv("XDG_CONFIG_HOME", orig)
+
+	cacheDir := t.TempDir()
+	origCache := os.Getenv("XDG_CACHE_HOME")
+	os.Setenv("XDG_CACHE_HOME", cacheDir)
+	defer os.Setenv("XDG_CACHE_HOME", origCache)
+
+	entries := []hook.AliasEntry{{Name: "web01", Host: "web01.example.com"}}
+	if err := hook.WriteAliasFiles(entries); err != nil {
+		t.Fatalf("WriteAliasFiles: %v", err)
+	}
+
+	if _, err := os.Stat(hook.FishAliasesPath()); err == nil {
+		t.Error("fish alias file should not be created when fish is not configured")
+	}
+}
+
+// TestWriteAliasFiles_EmptyEntries verifies an empty (but valid) file is written.
+func TestWriteAliasFiles_EmptyEntries(t *testing.T) {
+	cacheDir := t.TempDir()
+	orig := os.Getenv("XDG_CACHE_HOME")
+	os.Setenv("XDG_CACHE_HOME", cacheDir)
+	defer os.Setenv("XDG_CACHE_HOME", orig)
+
+	if err := hook.WriteAliasFiles(nil); err != nil {
+		t.Fatalf("WriteAliasFiles with nil entries: %v", err)
+	}
+	data, err := os.ReadFile(hook.AliasesPath())
+	if err != nil {
+		t.Fatalf("aliases.sh not created: %v", err)
+	}
+	// Should contain only the header comment, no alias lines.
+	if strings.Contains(string(data), "alias ") {
+		t.Error("aliases.sh should have no alias lines for empty entries")
+	}
+}
+
+// --- InstallAliasesSource ---
+
+func TestInstallAliasesSource_Fresh(t *testing.T) {
+	profile := writeProfile(t, "existing line\n")
+
+	installed, err := hook.InstallAliasesSource(profile)
+	if err != nil {
+		t.Fatalf("InstallAliasesSource: %v", err)
+	}
+	if !installed {
+		t.Error("should report installed=true on first install")
+	}
+
+	data, _ := os.ReadFile(profile)
+	if !strings.Contains(string(data), hook.AliasesMarker) {
+		t.Error("profile should contain aliases source line")
+	}
+}
+
+func TestInstallAliasesSource_Idempotent(t *testing.T) {
+	profile := writeProfile(t, "")
+
+	hook.InstallAliasesSource(profile)
+	installed, err := hook.InstallAliasesSource(profile)
+	if err != nil {
+		t.Fatalf("second InstallAliasesSource: %v", err)
+	}
+	if installed {
+		t.Error("second call should report installed=false")
+	}
+
+	data, _ := os.ReadFile(profile)
+	if count := strings.Count(string(data), hook.AliasesMarker); count != 1 {
+		t.Errorf("aliases source line should appear once, got %d", count)
+	}
+}
+
+// TestUninstall_AlsoRemovesAliasesSourceLine verifies that Uninstall removes both lines.
+func TestUninstall_AlsoRemovesAliasesSourceLine(t *testing.T) {
+	content := "export PATH=$PATH\n" +
+		hook.Line + "\n" +
+		hook.AliasesSourceLine + "\n" +
+		"export FOO=bar\n"
+	profile := writeProfile(t, content)
+
+	removed, err := hook.Uninstall(profile)
+	if err != nil {
+		t.Fatalf("Uninstall: %v", err)
+	}
+	if !removed {
+		t.Error("should report removed=true")
+	}
+
+	data, _ := os.ReadFile(profile)
+	s := string(data)
+	if strings.Contains(s, hook.Marker) {
+		t.Error("shell-init line should be removed")
+	}
+	if strings.Contains(s, hook.AliasesMarker) {
+		t.Error("aliases source line should be removed")
+	}
+	if !strings.Contains(s, "export PATH") || !strings.Contains(s, "export FOO") {
+		t.Error("other content should be preserved")
+	}
+}

internal/hook/hook.go

@@ -8,10 +8,15 @@ import (
 )
 
 const (
-	// Marker is the unique string used to detect an existing hook installation.
+	// Marker is the unique string used to detect an existing hook line.
 	Marker = "netssh shell-init"
 	// Line is the full line written into the shell profile.
 	Line = "netssh shell-init  # netssh cache auto-refresh"
+
+	// AliasesMarker is the unique string used to detect the aliases source line.
+	AliasesMarker = "netssh/aliases.sh"
+	// AliasesSourceLine is the bash/zsh line that sources the generated aliases file.
+	AliasesSourceLine = "source ~/.cache/netssh/aliases.sh 2>/dev/null  # netssh aliases"
 )
 
 // ProfilePath returns the canonical shell profile path for the given shell name.
@@ -68,8 +73,30 @@ func Install(profilePath string) (installed bool, err error) {
 	return true, nil
 }
 
-// Uninstall removes the hook line from the profile.
-// Returns (true, nil) when removed, (false, nil) when the hook was not found.
+// InstallAliasesSource appends the aliases source line to a bash/zsh profile.
+// This is a no-op for fish (which uses conf.d auto-sourcing instead).
+// Returns (true, nil) when newly added, (false, nil) when already present.
+func InstallAliasesSource(profilePath string) (installed bool, err error) {
+	data, err := os.ReadFile(profilePath)
+	if err != nil && !os.IsNotExist(err) {
+		return false, fmt.Errorf("reading profile: %w", err)
+	}
+	if strings.Contains(string(data), AliasesMarker) {
+		return false, nil
+	}
+	f, err := os.OpenFile(profilePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
+	if err != nil {
+		return false, fmt.Errorf("opening profile: %w", err)
+	}
+	defer f.Close()
+	if _, err := fmt.Fprintf(f, "%s\n", AliasesSourceLine); err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+// Uninstall removes the hook line and the aliases source line from the profile.
+// Returns (true, nil) when something was removed, (false, nil) when nothing was found.
 // Returns (false, nil) — not an error — when the file does not exist.
 func Uninstall(profilePath string) (removed bool, err error) {
 	data, err := os.ReadFile(profilePath)
@@ -80,13 +107,13 @@ func Uninstall(profilePath string) (removed bool, err error) {
 		return false, fmt.Errorf("reading profile: %w", err)
 	}
 	content := string(data)
-	if !strings.Contains(content, Marker) {
+	if !strings.Contains(content, Marker) && !strings.Contains(content, AliasesMarker) {
 		return false, nil
 	}
 
 	var kept []string
 	for _, line := range strings.Split(content, "\n") {
-		if strings.Contains(line, Marker) {
+		if strings.Contains(line, Marker) || strings.Contains(line, AliasesMarker) {
 			continue
 		}
 		kept = append(kept, line)