Pull request 2475: AG-46192-lang-validation

Squashed commit of the following:

commit 4129832c67272fa28c2cee0caeb0859900c9fb28
Merge: c3db487b9 b4f1ab280
Author: Igor Lobanov <i.lobanov@adguard.com>
Date:   Mon Sep 22 11:06:22 2025 +0200

    Merge branch 'master' into AG-46192-lang-validation
    
    # Conflicts:
    #	CHANGELOG.md

commit c3db487b9d
Author: Ildar Kamalov <ik@adguard.com>
Date:   Fri Sep 19 16:12:06 2025 +0300

    ADG-10728 remove language update request on page reload

commit 20f3a3057b
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Tue Sep 16 15:47:50 2025 +0300

    home: imp naming

commit 942c28f4c0
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Tue Sep 16 13:15:28 2025 +0300

    all: add tests

commit a871d51341
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Sep 15 18:09:30 2025 +0300

    home: lang validation

CHANGELOG.md

@@ -28,6 +28,7 @@ NOTE: Add new changes BELOW THIS COMMENT.
 
 ### Fixed
 
+- Excessive configuration file overwrites when visiting the Web UI and a non-empty `language` is set.
 - Lowered the severity of log messages for failed deletion of old filter files ([#7964]).
 
 [#7964]: https://github.com/AdguardTeam/AdGuardHome/issues/7964

client/src/components/App/index.tsx

@@ -26,7 +26,7 @@ import { getLogsUrlParams, setHtmlLangAttr, setUITheme } from '../../helpers/hel
 
 import Header from '../Header';
 
-import { changeLanguage, getDnsStatus, getTimerStatus } from '../../actions';
+import { getDnsStatus, getTimerStatus } from '../../actions';
 
 import Dashboard from '../../containers/Dashboard';
 import SetupGuide from '../../containers/SetupGuide';
@@ -134,16 +134,12 @@ const App = () => {
     }, []);
 
     const setLanguage = () => {
-        if (!processing) {
-            if (language) {
-                i18n.changeLanguage(language);
-                setHtmlLangAttr(language);
-            }
+        if (processing || !language) {
+            return;
         }
 
-        i18n.on('languageChanged', (lang) => {
-            dispatch(changeLanguage(lang));
-        });
+        i18n.changeLanguage(language);
+        setHtmlLangAttr(language);
     };
 
     useEffect(() => {

client/src/components/ui/Footer.tsx

@@ -13,7 +13,7 @@ import './Select.css';
 
 import { setHtmlLangAttr, setUITheme } from '../../helpers/helpers';
 
-import { changeTheme } from '../../actions';
+import { changeLanguage, changeTheme } from '../../actions';
 import { RootState } from '../../initialState';
 
 const linksData = [
@@ -46,10 +46,10 @@ const Footer = () => {
         return today.getFullYear();
     };
 
-    const changeLanguage = (event: any) => {
-        const { value } = event.target;
-        i18n.changeLanguage(value);
-        setHtmlLangAttr(value);
+    const onLanguageChange = (language: string) => {
+        i18n.changeLanguage(language);
+        setHtmlLangAttr(language);
+        dispatch(changeLanguage(language));
     };
 
     const onThemeChange = (value: any) => {
@@ -143,7 +143,7 @@ const Footer = () => {
                             <select
                                 className="form-control select select--language"
                                 value={i18n.language}
-                                onChange={changeLanguage}>
+                                onChange={(e) => onLanguageChange(e.target.value)}>
                                 {Object.keys(LANGUAGES).map((lang) => (
                                     <option key={lang} value={lang}>
                                         {LANGUAGES[lang]}

internal/home/config.go

@@ -721,6 +721,14 @@ func validateConfig(ctx context.Context, l *slog.Logger) (err error) {
 		l.WarnContext(ctx, "no users in the configuration file; authentication is disabled")
 	}
 
+	if config.Language != "" && !allowedLanguages.Has(config.Language) {
+		l.WarnContext(ctx, "unsupported language", "lang", config.Language)
+
+		// Clear the language so the frontend can use the client's browser
+		// language.
+		config.Language = ""
+	}
+
 	return nil
 }
 

internal/home/profilehttp.go

@@ -99,16 +99,26 @@ func (web *webAPI) handlePutProfile(w http.ResponseWriter, r *http.Request) {
 
 	theme := profileReq.Theme
 
+	changed := false
 	func() {
 		config.Lock()
 		defer config.Unlock()
 
+		if config.Language == lang && config.Theme == theme {
+			web.logger.DebugContext(ctx, "updating profile; no changes")
+
+			return
+		}
+
+		changed = true
 		config.Language = lang
 		config.Theme = theme
 		web.logger.InfoContext(ctx, "profile updated", "lang", lang, "theme", theme)
 	}()
 
-	web.confModifier.Apply(ctx)
+	if changed {
+		web.confModifier.Apply(ctx)
+	}
 
 	aghhttp.OK(w)
 }

internal/home/profilehttp_internal_test.go

@@ -1,7 +1,11 @@
 package home
 
 import (
+	"bytes"
+	"context"
 	"encoding/binary"
+	"encoding/json"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -10,6 +14,10 @@ import (
 	"time"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/agh"
+	"github.com/AdguardTeam/AdGuardHome/internal/aghhttp"
+	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
+	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/httphdr"
 	"github.com/AdguardTeam/golibs/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -117,3 +125,123 @@ func TestWeb_HandleGetProfile(t *testing.T) {
 		assert.Equal(t, http.StatusUnauthorized, w.Code)
 	}))
 }
+
+func TestWeb_HandlePutProfile(t *testing.T) {
+	storeGlobals(t)
+
+	mux := http.NewServeMux()
+	globalContext.mux = mux
+
+	isConfigChanged := false
+	confModifier := &aghtest.ConfigModifier{
+		OnApply: func(_ context.Context) { isConfigChanged = true },
+	}
+
+	ctx := testutil.ContextWithTimeout(t, testTimeout)
+	web, err := initWeb(ctx, options{}, nil, nil, testLogger, nil, nil, confModifier, false)
+	require.NoError(t, err)
+
+	globalContext.web = web
+
+	var (
+		dataValid = errors.Must(json.Marshal(&profileJSON{
+			Language: "en",
+			Theme:    "auto",
+		}))
+
+		dataInvalidLang = errors.Must(json.Marshal(&profileJSON{
+			Language: "invalid_lang",
+			Theme:    "auto",
+		}))
+
+		dataInvalidTheme = errors.Must(json.Marshal(&profileJSON{
+			Language: "en",
+			Theme:    "invalid_theme",
+		}))
+	)
+
+	testCases := []struct {
+		req      *http.Request
+		name     string
+		wantBody string
+		wantCode int
+	}{{
+		req:      newProfileUpdateRequest(http.MethodPut, dataValid, true),
+		name:     "basic",
+		wantBody: "OK\n",
+		wantCode: http.StatusOK,
+	}, {
+		req:      newProfileUpdateRequest(http.MethodGet, dataValid, true),
+		name:     "invalid_method",
+		wantBody: "only method PUT is allowed\n",
+		wantCode: http.StatusMethodNotAllowed,
+	}, {
+		req:      newProfileUpdateRequest(http.MethodPut, dataValid, false),
+		name:     "invalid_content_type",
+		wantBody: "only content-type application/json is allowed\n",
+		wantCode: http.StatusUnsupportedMediaType,
+	}, {
+		req:      newProfileUpdateRequest(http.MethodPut, nil, false),
+		name:     "empty_body",
+		wantBody: "reading req: EOF\n",
+		wantCode: http.StatusBadRequest,
+	}, {
+		req:      newProfileUpdateRequest(http.MethodPut, dataInvalidLang, true),
+		name:     "invalid_language",
+		wantBody: `unknown language: "invalid_lang"` + "\n",
+		wantCode: http.StatusBadRequest,
+	}, {
+		req:  newProfileUpdateRequest(http.MethodPut, dataInvalidTheme, true),
+		name: "invalid_theme",
+		wantBody: `reading req: invalid theme "invalid_theme", ` +
+			`supported: "auto", "dark", "light"` + "\n",
+		wantCode: http.StatusBadRequest,
+	}}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			w := httptest.NewRecorder()
+
+			mux.ServeHTTP(w, tc.req)
+			assert.Equal(t, tc.wantCode, w.Code)
+			assert.Equal(t, tc.wantBody, w.Body.String())
+		})
+	}
+
+	require.True(t, t.Run("single_config_update", func(t *testing.T) {
+		isConfigChanged = false
+		config.Language = ""
+		config.Theme = ""
+
+		w := httptest.NewRecorder()
+
+		mux.ServeHTTP(w, newProfileUpdateRequest(http.MethodPut, dataValid, true))
+		require.Equal(t, http.StatusOK, w.Code)
+
+		assert.True(t, isConfigChanged)
+
+		isConfigChanged = false
+
+		mux.ServeHTTP(w, newProfileUpdateRequest(http.MethodPut, dataValid, true))
+		require.Equal(t, http.StatusOK, w.Code)
+
+		assert.False(t, isConfigChanged)
+	}))
+}
+
+// newProfileUpdateRequest builds an *http.Request for the profile update
+// endpoint.  If body is non-nil, it is used as the request body.  If setCT is
+// true, the Content-Type header is set to application/json.
+func newProfileUpdateRequest(method string, body []byte, setCT bool) (req *http.Request) {
+	var r io.Reader
+	if body != nil {
+		r = bytes.NewReader(body)
+	}
+
+	req = httptest.NewRequest(method, "/control/profile/update", r)
+	if setCT {
+		req.Header.Set(httphdr.ContentType, aghhttp.HdrValApplicationJSON)
+	}
+
+	return req
+}