Implemented locale initialization based on browser settings, added methods to determine locale from URL parameters and Accept-Language header, and updated app initialization to include locale setup.

src/app.cpp

@@ -41,12 +41,14 @@
 #include <Wt/WCheckBox.h>
 #include <Wt/WTimer.h>
 #include <Wt/WResource.h>
+#include <Wt/WLocale.h>
 
 App::App(const Wt::WEnvironment &env, Broadcast &server):
         Wt::WApplication(env),
         env_(env),
         server_(server),
         updateLocationSignal_(this, "updateLocationSignal") {
+    initLocale();
     initApp();
     updateLocation();
     enableUpdates(true);
@@ -66,6 +68,95 @@ void App::setMetaTags() {
     addMetaHeader(Wt::MetaHeaderType::Meta, "google-adsense-account", "ca-pub-1104166651501135");
 }
 
+void App::initLocale() {
+    auto locale = determineLocaleFromBrowser();
+    setLocale(locale);
+}
+
+Wt::WLocale App::determineLocaleFromBrowser() const {
+    auto makeLocale = [](const std::string &code) -> Wt::WLocale {
+        return Wt::WLocale(code);
+    };
+
+    auto mapLanguageTag = [&makeLocale](std::string tag) -> std::string {
+        // trim
+        auto begin = tag.find_first_not_of(" \t");
+        auto end = tag.find_last_not_of(" \t");
+        if (begin == std::string::npos) {
+            return "";
+        }
+        tag = tag.substr(begin, end - begin + 1);
+
+        // nur Sprach-/Regionscode ohne q-Wert
+        auto semicolonPos = tag.find(';');
+        if (semicolonPos != std::string::npos) {
+            tag = tag.substr(0, semicolonPos);
+        }
+
+        std::string lower = tag;
+        std::transform(lower.begin(), lower.end(), lower.begin(), ::tolower);
+
+        // Sprache und Region trennen
+        std::string lang = lower;
+        std::string region;
+        auto dashPos = lower.find('-');
+        if (dashPos != std::string::npos) {
+            lang = lower.substr(0, dashPos);
+            region = lower.substr(dashPos + 1);
+        }
+
+        if (lang == "en") {
+            if (region == "us") {
+                return "en_US";
+            }
+            // Standard: britisches Englisch
+            return "en_GB";
+        } else if (lang == "de") {
+            return "de_DE";
+        } else if (lang == "fr") {
+            return "fr_FR";
+        } else if (lang == "es") {
+            return "es_ES";
+        } else if (lang == "it") {
+            return "it_IT";
+        } else if (lang == "tl" || lang == "fil") {
+            return "tl_PH";
+        } else if (lang == "ja") {
+            return "ja_JP";
+        } else if (lang == "zh") {
+            return "zh_CN";
+        } else if (lang == "th") {
+            return "th_TH";
+        }
+
+        return "";
+    };
+
+    // 1. Expliziter URL-Parameter ?lang=... hat Vorrang (z.B. de, de-DE, en, en-US, fr, es, it, tl, ja, zh, th)
+    if (const auto *langParam = env_.getParameter("lang")) {
+        auto localeName = mapLanguageTag(langParam->toUTF8());
+        if (!localeName.empty()) {
+            return makeLocale(localeName);
+        }
+    }
+
+    // 2. Sonst Accept-Language Header des Browsers auswerten
+    std::string accept = env_.headerValue("Accept-Language");
+    if (!accept.empty()) {
+        std::stringstream ss(accept);
+        std::string part;
+        while (std::getline(ss, part, ',')) {
+            auto localeName = mapLanguageTag(part);
+            if (!localeName.empty()) {
+                return makeLocale(localeName);
+            }
+        }
+    }
+
+    // Fallback: britisches Englisch
+    return makeLocale("en_GB");
+}
+
 void App::initApp() {
     setMetaTags();
     setTitle("YP Direct Chat");

src/app.h

@@ -99,6 +99,8 @@ private:
     Wt::WTimer *timeoutRemainingTimer_;
     bool isLoggedInAsAdmin {false};
     void setMetaTags();
+    void initLocale();
+    Wt::WLocale determineLocaleFromBrowser() const;
     void initApp();
     void reSetUser();
     Wt::WVBoxLayout *createVerticalLayout();