fix: add locale

internal/modules/system/locale.go

@@ -2,6 +2,10 @@ package system
 
 import (
 	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
 	"slices"
 	"strings"
 
@@ -42,6 +46,16 @@ type SetKeymapInput struct {
 	}
 }
 
+type GenerateLocaleInput struct {
+	Body struct {
+		Locale string `json:"locale" example:"fr_FR.UTF-8" doc:"Locale to generate (e.g. fr_FR.UTF-8)"`
+	}
+}
+
+// localeRe validates a locale identifier: language_TERRITORY with an optional
+// .charmap suffix (e.g. fr_FR, fr_FR.UTF-8, en_US.ISO-8859-1).
+var localeRe = regexp.MustCompile(`^[a-z]{2,3}_[A-Z]{2}(\.[A-Za-z0-9_-]+)?$`)
+
 func localeStatus() (LocaleStatusBody, error) {
 	lines, err := oscmd.RunLines("localectl", "status")
 	if err != nil {
@@ -183,4 +197,117 @@ func registerLocale(api huma.API) {
 		}
 		return oscmd.OK(), nil
 	})
+
+	huma.Register(api, huma.Operation{
+		OperationID: "system-generate-locale",
+		Method:      "POST",
+		Path:        "/api/system/locale/generate",
+		Summary:     "Generate (install) a new locale",
+		Description: "Generates a locale so it becomes available for use with set-locale. " +
+			"On Debian/Ubuntu/Arch this uncomments the entry in /etc/locale.gen and runs " +
+			"locale-gen; on RHEL/Fedora it uses localedef. Idempotent: if the locale is " +
+			"already generated, returns 200 immediately.",
+		Tags:     []string{tagSystem},
+		Metadata: op("write"),
+		Errors:   append(writeErrors, 501),
+	}, func(ctx context.Context, in *GenerateLocaleInput) (*oscmd.StatusOutput, error) {
+		locale := strings.TrimSpace(in.Body.Locale)
+		if locale == "" {
+			return nil, huma.Error400BadRequest("empty locale")
+		}
+		if !localeRe.MatchString(locale) {
+			return nil, huma.Error400BadRequest("invalid locale format: "+locale,
+				fmt.Errorf("expected language_TERRITORY[.charmap], e.g. fr_FR.UTF-8"))
+		}
+
+		// Idempotency: already generated → success.
+		existing, err := oscmd.RunLines("localectl", "list-locales")
+		if err != nil {
+			return nil, huma.Error500InternalServerError("localectl failed", err)
+		}
+		if slices.Contains(existing, locale) {
+			return oscmd.OK(), nil
+		}
+
+		// Detect which generation path the host supports.
+		localeGenFile := "/etc/locale.gen"
+		_, hasFile := os.Stat(localeGenFile)
+		_, hasLocaleGen := exec.LookPath("locale-gen")
+		_, hasLocaledef := exec.LookPath("localedef")
+
+		switch {
+		case hasFile == nil && hasLocaleGen == nil:
+			if err := enableLocaleGen(localeGenFile, locale); err != nil {
+				return nil, err
+			}
+		case hasLocaledef == nil:
+			if err := generateLocaledef(locale); err != nil {
+				return nil, err
+			}
+		default:
+			return nil, huma.Error501NotImplemented(
+				"locale generation not supported on this host (no locale-gen or localedef found)")
+		}
+		return oscmd.OK(), nil
+	})
+}
+
+// enableLocaleGen uncomments the locale in /etc/locale.gen and runs locale-gen.
+// This is the Debian/Ubuntu/Arch path.
+func enableLocaleGen(path, locale string) error {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return huma.Error500InternalServerError("reading locale.gen failed", err)
+	}
+	newContent, found := uncommentLocaleGen(string(data), locale)
+	if !found {
+		return huma.Error400BadRequest("locale not available for generation: " + locale)
+	}
+	if err := os.WriteFile(path, []byte(newContent), 0644); err != nil {
+		return huma.Error500InternalServerError("writing locale.gen failed", err)
+	}
+	if _, err := oscmd.Run("locale-gen"); err != nil {
+		return huma.Error500InternalServerError("locale-gen failed", err)
+	}
+	return nil
+}
+
+// uncommentLocaleGen finds a commented-out line for the given locale in a
+// locale.gen file and uncomments it. Returns the modified content and whether
+// a matching line was found. Pure function for testability.
+func uncommentLocaleGen(content, locale string) (string, bool) {
+	lines := strings.Split(content, "\n")
+	found := false
+	for i, line := range lines {
+		trimmed := strings.TrimSpace(line)
+		// Match lines like "# fr_FR.UTF-8 UTF-8" or "#fr_FR.UTF-8 UTF-8".
+		if !strings.HasPrefix(trimmed, "#") {
+			// Also check if already uncommented (idempotent at the file level).
+			if strings.HasPrefix(trimmed, locale+" ") || trimmed == locale {
+				found = true
+			}
+			continue
+		}
+		uncommented := strings.TrimSpace(strings.TrimPrefix(trimmed, "#"))
+		if strings.HasPrefix(uncommented, locale+" ") || uncommented == locale {
+			lines[i] = uncommented
+			found = true
+		}
+	}
+	return strings.Join(lines, "\n"), found
+}
+
+// generateLocaledef generates a locale using localedef. This is the RHEL/Fedora
+// path where there is no /etc/locale.gen.
+func generateLocaledef(locale string) error {
+	// Parse "fr_FR.UTF-8" into language_territory="fr_FR" and charmap="UTF-8".
+	// If there is no dot, default to UTF-8 (the common case on modern systems).
+	langTerritory, charmap, _ := strings.Cut(locale, ".")
+	if charmap == "" {
+		charmap = "UTF-8"
+	}
+	if _, err := oscmd.Run("localedef", "-i", langTerritory, "-f", charmap, locale); err != nil {
+		return huma.Error500InternalServerError("localedef failed", err)
+	}
+	return nil
 }

internal/modules/system/system_handler_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"reflect"
+	"strings"
 	"testing"
 
 	"nadir/internal/oscmd"
@@ -199,6 +200,37 @@ func TestSystemHandlers(t *testing.T) {
 		t.Errorf("set keymap: got %d, want %d", resp.Code, http.StatusOK)
 	}
 
+	// 4b. Test POST /api/system/locale/generate (validation & idempotent)
+	// Empty locale → 422 (huma validates non-empty before handler runs)
+	resp = api.Post("/api/system/locale/generate", struct {
+		Locale string `json:"locale"`
+	}{
+		Locale: "",
+	})
+	if resp.Code != http.StatusBadRequest && resp.Code != http.StatusUnprocessableEntity {
+		t.Errorf("generate empty locale: got %d, want 400 or 422", resp.Code)
+	}
+
+	// Invalid format → 400
+	resp = api.Post("/api/system/locale/generate", struct {
+		Locale string `json:"locale"`
+	}{
+		Locale: "not-a-locale!!",
+	})
+	if resp.Code != http.StatusBadRequest {
+		t.Errorf("generate invalid locale: got %d, want %d", resp.Code, http.StatusBadRequest)
+	}
+
+	// Already generated (it_IT.UTF-8 is in list-locales mock) → 200 (idempotent)
+	resp = api.Post("/api/system/locale/generate", struct {
+		Locale string `json:"locale"`
+	}{
+		Locale: "it_IT.UTF-8",
+	})
+	if resp.Code != http.StatusOK {
+		t.Errorf("generate existing locale (idempotent): got %d, want %d", resp.Code, http.StatusOK)
+	}
+
 	// 5. Test POST /api/system/reboot and /api/system/poweroff
 	oscmd.SetMock("shutdown", func(args []string) oscmd.MockCommand {
 		if reflect.DeepEqual(args, []string{"-r", "now"}) || reflect.DeepEqual(args, []string{"-h", "now"}) {
@@ -225,3 +257,58 @@ func TestSystemHandlers(t *testing.T) {
 		t.Errorf("poweroff: got %d, want %d", resp.Code, http.StatusOK)
 	}
 }
+
+func TestUncommentLocaleGen(t *testing.T) {
+	const sampleLocaleGen = `# This file lists locales that you wish to have built.
+#
+# en_US.UTF-8 UTF-8
+# fr_FR.UTF-8 UTF-8
+# de_DE.UTF-8 UTF-8
+it_IT.UTF-8 UTF-8
+`
+
+	tests := []struct {
+		name       string
+		locale     string
+		wantFound  bool
+		wantSubstr string // substring that should appear uncommented
+	}{
+		{
+			name:       "uncomment commented locale",
+			locale:     "fr_FR.UTF-8",
+			wantFound:  true,
+			wantSubstr: "\nfr_FR.UTF-8 UTF-8\n",
+		},
+		{
+			name:      "already uncommented",
+			locale:    "it_IT.UTF-8",
+			wantFound: true,
+		},
+		{
+			name:      "locale not in file",
+			locale:    "ja_JP.UTF-8",
+			wantFound: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, found := uncommentLocaleGen(sampleLocaleGen, tt.locale)
+			if found != tt.wantFound {
+				t.Errorf("found = %v, want %v", found, tt.wantFound)
+			}
+			if tt.wantSubstr != "" && !contains(result, tt.wantSubstr) {
+				t.Errorf("result does not contain %q:\n%s", tt.wantSubstr, result)
+			}
+			// The commented versions of OTHER locales should remain commented.
+			if tt.locale == "fr_FR.UTF-8" && !contains(result, "# en_US.UTF-8 UTF-8") {
+				t.Errorf("other locales should stay commented:\n%s", result)
+			}
+		})
+	}
+}
+
+func contains(s, substr string) bool {
+	return len(s) >= len(substr) && (s == substr || len(substr) == 0 ||
+		(len(s) > 0 && strings.Contains(s, substr)))
+}