From cd96ee8456194e4a9557151c63a8bdbbe691c258 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=A0t=C4=9Bp=C3=A1n=20Gran=C3=A1t?=
 <granat.stepan@gmail.com>
Date: Fri, 11 Mar 2022 09:02:41 +0100
Subject: [PATCH] fix: Make language stable

---
 packages/core/src/Properties.test.ts | 13 ++++++++++
 packages/core/src/Properties.ts      | 38 +++++++++++++++-------------
 2 files changed, 34 insertions(+), 17 deletions(-)

diff --git a/packages/core/src/Properties.test.ts b/packages/core/src/Properties.test.ts
index 5bcee7c8af..20ff08e898 100644
--- a/packages/core/src/Properties.test.ts
+++ b/packages/core/src/Properties.test.ts
@@ -96,6 +96,19 @@ describe('Properties', () => {
       expect(properties.currentLanguage).toEqual('cs');
     });
 
+    test('language is stored locally and detected only once', () => {
+      const languageGetter = jest.spyOn(window.navigator, 'language', 'get');
+      languageGetter.mockReturnValue('cs');
+      Storage.prototype.getItem = jest.fn();
+      properties.config = new TolgeeConfig({
+        availableLanguages: ['cs', 'en'],
+      });
+      expect(properties.currentLanguage).toEqual('cs');
+      expect(properties.currentLanguage).toEqual('cs');
+
+      expect(languageGetter).toBeCalledTimes(1);
+    });
+
     test('available languages derrived from staticData', () => {
       const languageGetter = jest.spyOn(window.navigator, 'language', 'get');
       languageGetter.mockReturnValue('cs');
diff --git a/packages/core/src/Properties.ts b/packages/core/src/Properties.ts
index bfefdcfdec..a11a1b099e 100644
--- a/packages/core/src/Properties.ts
+++ b/packages/core/src/Properties.ts
@@ -15,25 +15,11 @@ export class Properties {
       return this.config.forceLanguage;
     }
 
-    if (this._currentLanguage) {
-      return this._currentLanguage;
+    if (!this._currentLanguage) {
+      this._currentLanguage = this.getInitialLanguage();
     }
 
-    if (this.config.enableLanguageStore) {
-      const storedLanguage = this.getStoredLanguage();
-      if (storedLanguage) {
-        return storedLanguage;
-      }
-    }
-
-    if (this.config.enableLanguageDetection) {
-      const detectedLanguage = this.getLanguageByNavigator();
-      if (detectedLanguage) {
-        return detectedLanguage;
-      }
-    }
-
-    return this.config.defaultLanguage;
+    return this._currentLanguage;
   }
 
   set currentLanguage(language: string) {
@@ -63,6 +49,24 @@ export class Properties {
     );
   }
 
+  private getInitialLanguage() {
+    if (this.config.enableLanguageStore) {
+      const storedLanguage = this.getStoredLanguage();
+      if (storedLanguage) {
+        return storedLanguage;
+      }
+    }
+
+    if (this.config.enableLanguageDetection) {
+      const detectedLanguage = this.getLanguageByNavigator();
+      if (detectedLanguage) {
+        return detectedLanguage;
+      }
+    }
+
+    return this.config.defaultLanguage;
+  }
+
   private getStoredLanguage() {
     if (typeof localStorage !== 'undefined') {
       const storedLanguage = localStorage.getItem(