Feature: Implement language pack support for display texts

include/I18n.h

@@ -16,7 +16,14 @@ class I18nClass {
     I18nClass();
     void init(Scheduler& scheduler);
     std::list<LanguageInfo_t> getAvailableLanguages();
-    String getFilenameByLocale(String& locale) const;
+    String getFilenameByLocale(const String& locale) const;
+    void readDisplayStrings(
+        const String& locale,
+        String& date_format,
+        String& offline,
+        String& power_w, String& power_kw,
+        String& yield_today_wh, String& yield_today_kwh,
+        String& yield_total_kwh, String& yield_total_mwh);
 
 private:
     void readLangPacks();

src/Display_Graphic.cpp

@@ -4,6 +4,7 @@
  */
 #include "Display_Graphic.h"
 #include "Datastore.h"
+#include "I18n.h"
 #include <NetworkSettings.h>
 #include <map>
 #include <time.h>
@@ -169,14 +170,24 @@ void DisplayGraphicClass::setLocale(const String& locale)
         idx = I18N_LOCALE_FR;
     }
 
-    _i18n_offline = i18n_offline[idx];
-    _i18n_yield_today_kwh = i18n_yield_today_kwh[idx];
-    _i18n_yield_today_wh = i18n_yield_today_wh[idx];
     _i18n_date_format = i18n_date_format[idx];
-    _i18n_current_power_kw = i18n_current_power_kw[idx];
+    _i18n_offline = i18n_offline[idx];
     _i18n_current_power_w = i18n_current_power_w[idx];
-    _i18n_yield_total_mwh = i18n_yield_total_mwh[idx];
+    _i18n_current_power_kw = i18n_current_power_kw[idx];
+    _i18n_yield_today_wh = i18n_yield_today_wh[idx];
+    _i18n_yield_today_kwh = i18n_yield_today_kwh[idx];
     _i18n_yield_total_kwh = i18n_yield_total_kwh[idx];
+    _i18n_yield_total_mwh = i18n_yield_total_mwh[idx];
+
+    I18n.readDisplayStrings(locale,
+        _i18n_date_format,
+        _i18n_offline,
+        _i18n_current_power_w,
+        _i18n_current_power_kw,
+        _i18n_yield_today_wh,
+        _i18n_yield_today_kwh,
+        _i18n_yield_total_kwh,
+        _i18n_yield_total_mwh);
 }
 
 void DisplayGraphicClass::setDiagramMode(DiagramMode_t mode)

src/I18n.cpp

@@ -25,7 +25,7 @@ std::list<LanguageInfo_t> I18nClass::getAvailableLanguages()
     return _availLanguages;
 }
 
-String I18nClass::getFilenameByLocale(String& locale) const
+String I18nClass::getFilenameByLocale(const String& locale) const
 {
     auto it = std::find_if(_availLanguages.begin(), _availLanguages.end(), [locale](const LanguageInfo_t& elem) {
         return elem.code == locale;
@@ -38,6 +38,75 @@ String I18nClass::getFilenameByLocale(String& locale) const
     }
 }
 
+void I18nClass::readDisplayStrings(
+    const String& locale,
+    String& date_format,
+    String& offline,
+    String& power_w, String& power_kw,
+    String& yield_today_wh, String& yield_today_kwh,
+    String& yield_total_kwh, String& yield_total_mwh)
+{
+    auto filename = getFilenameByLocale(locale);
+    if (filename == "") {
+        return;
+    }
+
+    JsonDocument filter;
+    filter["display"] = true;
+
+    File f = LittleFS.open(filename, "r", false);
+
+    JsonDocument doc;
+
+    // Deserialize the JSON document
+    const DeserializationError error = deserializeJson(doc, f, DeserializationOption::Filter(filter));
+    if (error) {
+        MessageOutput.printf("Failed to read file %s\r\n", filename.c_str());
+        f.close();
+        return;
+    }
+
+    if (!Utils::checkJsonAlloc(doc, __FUNCTION__, __LINE__)) {
+        return;
+    }
+
+    auto displayData = doc["display"];
+
+    if (displayData["date_format"].as<String>() != "null") {
+        date_format = displayData["date_format"].as<String>();
+    }
+
+    if (displayData["offline"].as<String>() != "null") {
+        offline = displayData["offline"].as<String>();
+    }
+
+    if (displayData["power_w"].as<String>() != "null") {
+        power_w = displayData["power_w"].as<String>();
+    }
+
+    if (displayData["power_kw"].as<String>() != "null") {
+        power_kw = displayData["power_kw"].as<String>();
+    }
+
+    if (displayData["yield_today_wh"].as<String>() != "null") {
+        yield_today_wh = displayData["yield_today_wh"].as<String>();
+    }
+
+    if (displayData["yield_today_kwh"].as<String>() != "null") {
+        yield_today_kwh = displayData["yield_today_kwh"].as<String>();
+    }
+
+    if (displayData["yield_total_kwh"].as<String>() != "null") {
+        yield_total_kwh = displayData["yield_total_kwh"].as<String>();
+    }
+
+    if (displayData["yield_total_mwh"].as<String>() != "null") {
+        yield_total_mwh = displayData["yield_total_mwh"].as<String>();
+    }
+
+    f.close();
+}
+
 void I18nClass::readLangPacks()
 {
     auto root = LittleFS.open("/");
@@ -79,7 +148,7 @@ void I18nClass::readConfig(String file)
     lang.name = String(doc["meta"]["name"] | "");
     lang.filename = file;
 
-    if (lang.code !=  "" && lang.name != "") {
+    if (lang.code != "" && lang.name != "") {
         _availLanguages.push_back(lang);
     } else {
         MessageOutput.printf("Invalid meta data\r\n");

webapp/src/views/DeviceAdminView.vue

@@ -1,5 +1,5 @@
 <template>
-    <BasePage :title="$t('deviceadmin.DeviceManager')" :isLoading="dataLoading || pinMappingLoading">
+    <BasePage :title="$t('deviceadmin.DeviceManager')" :isLoading="dataLoading || pinMappingLoading || languageLoading">
         <BootstrapAlert v-model="showAlert" dismissible :variant="alertType">
             {{ alertMessage }}
         </BootstrapAlert>
@@ -162,11 +162,11 @@
                                 <div class="col-sm-10">
                                     <select class="form-select" v-model="deviceConfigList.display.locale">
                                         <option
-                                            v-for="locale in displayLocaleList"
-                                            :key="locale.key"
-                                            :value="locale.key"
+                                            v-for="(locale, index) in displayLocaleList"
+                                            :key="locale.code"
+                                            :value="locale.code"
                                         >
-                                            {{ $t(`deviceadmin.` + locale.value) }}
+                                            {{ $t((index < 3 ? `deviceadmin.` : ``) + locale.name) }}
                                         </option>
                                     </select>
                                 </div>
@@ -277,6 +277,7 @@ export default defineComponent({
         return {
             dataLoading: true,
             pinMappingLoading: true,
+            languageLoading: true,
             deviceConfigList: {} as DeviceConfig,
             pinMappingList: {} as PinMapping,
             alertMessage: '',
@@ -290,9 +291,9 @@ export default defineComponent({
                 { key: 3, value: 'rot270' },
             ],
             displayLocaleList: [
-                { key: 'en', value: 'en' },
-                { key: 'de', value: 'de' },
-                { key: 'fr', value: 'fr' },
+                { code: 'en', name: 'en' },
+                { code: 'de', name: 'de' },
+                { code: 'fr', name: 'fr' },
             ],
             diagramModeList: [
                 { key: 0, value: 'off' },
@@ -304,6 +305,7 @@ export default defineComponent({
     created() {
         this.getDeviceConfig();
         this.getPinMappingList();
+        this.getLanguageList();
     },
     watch: {
         equalBrightnessCheckVal: function (val) {
@@ -314,6 +316,15 @@ export default defineComponent({
         },
     },
     methods: {
+        getLanguageList() {
+            this.languageLoading = true;
+            fetch('/api/i18n/languages')
+                .then((response) => handleResponse(response, this.$emitter, this.$router))
+                .then((data) => {
+                    this.displayLocaleList.push(...data);
+                    this.languageLoading = false;
+                });
+        },
         getPinMappingList() {
             this.pinMappingLoading = true;
             fetch('/api/file/get?file=pin_mapping.json', { headers: authHeader() })