From 916fa0741899afd7729e1c4a546048b44c0111b1 Mon Sep 17 00:00:00 2001
From: Rithvik Sriram <r.sriram-1@student.tudelft.nl>
Date: Thu, 15 Jan 2026 00:29:12 +0100
Subject: [PATCH] Add persistent language selection with ConfigService
 integration

---
 client/src/main/java/client/MyFXML.java       |  4 +-
 .../main/java/client/utils/LocaleManager.java | 24 +++++++-
 .../java/client/scenes/LocaleManagerTest.java | 61 +++++++++++++++++++
 3 files changed, 86 insertions(+), 3 deletions(-)
 create mode 100644 client/src/test/java/client/scenes/LocaleManagerTest.java

diff --git a/client/src/main/java/client/MyFXML.java b/client/src/main/java/client/MyFXML.java
index 0d5e9c5..995d3e2 100644
--- a/client/src/main/java/client/MyFXML.java
+++ b/client/src/main/java/client/MyFXML.java
@@ -19,6 +19,7 @@ import java.io.IOException;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 
+import client.utils.LocaleManager;
 import com.google.inject.Injector;
 
 import javafx.fxml.FXMLLoader;
@@ -38,7 +39,8 @@ public class MyFXML {
 
     public <T> Pair<T, Parent> load(Class<T> c, String... parts) {
         try {
-            var loader = new FXMLLoader(getLocation(parts), null, null, new MyFactory(), StandardCharsets.UTF_8);
+            var localeManager = injector.getInstance(LocaleManager.class);
+            var loader = new FXMLLoader(getLocation(parts), localeManager.getBundle(), null, new MyFactory(), StandardCharsets.UTF_8);
             Parent parent = loader.load();
             T ctrl = loader.getController();
             return new Pair<>(ctrl, parent);
diff --git a/client/src/main/java/client/utils/LocaleManager.java b/client/src/main/java/client/utils/LocaleManager.java
index edf342a..167228c 100644
--- a/client/src/main/java/client/utils/LocaleManager.java
+++ b/client/src/main/java/client/utils/LocaleManager.java
@@ -1,5 +1,6 @@
 package client.utils;
 
+import com.google.inject.Inject;
 import javafx.beans.property.ObjectProperty;
 import javafx.beans.property.SimpleObjectProperty;
 import java.util.Locale;
@@ -10,13 +11,30 @@ public class LocaleManager {
     private final ObjectProperty<ResourceBundle> currentBundle = new SimpleObjectProperty<>();
 
     private static final String RESOURCE_BUNDLE_PATH = "locale/lang";
+    private final ConfigService configService;
+
+    @Inject
+    public LocaleManager(ConfigService configService) {
+        this.configService = configService;
+        String savedLanguage = configService.getConfig().getLanguage();
+        Locale initialLocale = Locale.forLanguageTag(savedLanguage);
+        currentLocale.set(initialLocale);
 
-    public LocaleManager() {
-        // TODO: Set currentLocale to config value instead of EN default.
         updateBundle();
+
+        currentLocale.addListener((_, oldLocale, newLocale) -> {
+            updateBundle();
+            saveLanguagePreference(newLocale.getLanguage());
+        });
+
         currentLocale.addListener((_, _, _) -> updateBundle());
     }
 
+    private void saveLanguagePreference(String languageCode) {
+        configService.getConfig().setLanguage(languageCode);
+        configService.save();
+    }
+
     private void updateBundle() {
         ResourceBundle bundle = ResourceBundle.getBundle(RESOURCE_BUNDLE_PATH,
                 currentLocale.get(),
@@ -44,4 +62,6 @@ public class LocaleManager {
     public ObjectProperty<ResourceBundle> getBundleProperty() {
         return currentBundle;
     }
+
+
 }
\ No newline at end of file
diff --git a/client/src/test/java/client/scenes/LocaleManagerTest.java b/client/src/test/java/client/scenes/LocaleManagerTest.java
new file mode 100644
index 0000000..3116af3
--- /dev/null
+++ b/client/src/test/java/client/scenes/LocaleManagerTest.java
@@ -0,0 +1,61 @@
+package client.scenes;
+
+import client.utils.ConfigService;
+import client.utils.LocaleManager;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.nio.file.Path;
+import java.util.Locale;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+public class LocaleManagerTest {
+
+    @TempDir
+    Path tempDir;
+
+    private ConfigService configService;
+    private LocaleManager localeManager;
+
+    @BeforeEach
+    void setUp() {
+        Path configPath = tempDir.resolve("test-config.json");
+        configService = new ConfigService(configPath);
+        localeManager = new LocaleManager(configService);
+    }
+
+    @Test
+    void testSetLocaleChangesCurrentLocale() {
+        localeManager.setLocale(Locale.forLanguageTag("nl"));
+        assertEquals("nl", localeManager.getLocale().getLanguage());
+    }
+
+    @Test
+    void testSetLocaleSavesToConfig() {
+        localeManager.setLocale(Locale.forLanguageTag("pl"));
+        assertEquals("pl", configService.getConfig().getLanguage());
+    }
+
+    @Test
+    void testLocalePersistsAcrossInstances() {
+        localeManager.setLocale(Locale.forLanguageTag("en"));
+        LocaleManager newLocaleManager = new LocaleManager(configService);
+        assertEquals("en", newLocaleManager.getLocale().getLanguage());
+    }
+
+    @Test
+    void testBundleIsNotNull() {
+        assertNotNull(localeManager.getBundle());
+    }
+
+    @Test
+    void testBundlePropertyIsNotNull() {
+        assertNotNull(localeManager.getBundleProperty());
+        assertNotNull(localeManager.getBundleProperty().get());
+    }
+
+
+}